multi_buffer_tests.rs

   1use super::*;
   2use buffer_diff::{DiffHunkStatus, DiffHunkStatusKind};
   3use gpui::{App, TestAppContext};
   4use indoc::indoc;
   5use language::{Buffer, Rope};
   6use parking_lot::RwLock;
   7use rand::prelude::*;
   8use settings::SettingsStore;
   9use std::env;
  10use std::time::{Duration, Instant};
  11use util::RandomCharIter;
  12use util::rel_path::rel_path;
  13use util::test::sample_text;
  14
  15#[ctor::ctor]
  16fn init_logger() {
  17    zlog::init_test();
  18}
  19
  20#[gpui::test]
  21fn test_empty_singleton(cx: &mut App) {
  22    let buffer = cx.new(|cx| Buffer::local("", cx));
  23    let buffer_id = buffer.read(cx).remote_id();
  24    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
  25    let snapshot = multibuffer.read(cx).snapshot(cx);
  26    assert_eq!(snapshot.text(), "");
  27    assert_eq!(
  28        snapshot.row_infos(MultiBufferRow(0)).collect::<Vec<_>>(),
  29        [RowInfo {
  30            buffer_id: Some(buffer_id),
  31            buffer_row: Some(0),
  32            multibuffer_row: Some(MultiBufferRow(0)),
  33            diff_status: None,
  34            expand_info: None,
  35            wrapped_buffer_row: None,
  36        }]
  37    );
  38}
  39
  40#[gpui::test]
  41fn test_singleton(cx: &mut App) {
  42    let buffer = cx.new(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
  43    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
  44
  45    let snapshot = multibuffer.read(cx).snapshot(cx);
  46    assert_eq!(snapshot.text(), buffer.read(cx).text());
  47
  48    assert_eq!(
  49        snapshot
  50            .row_infos(MultiBufferRow(0))
  51            .map(|info| info.buffer_row)
  52            .collect::<Vec<_>>(),
  53        (0..buffer.read(cx).row_count())
  54            .map(Some)
  55            .collect::<Vec<_>>()
  56    );
  57    assert_consistent_line_numbers(&snapshot);
  58
  59    buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
  60    let snapshot = multibuffer.read(cx).snapshot(cx);
  61
  62    assert_eq!(snapshot.text(), buffer.read(cx).text());
  63    assert_eq!(
  64        snapshot
  65            .row_infos(MultiBufferRow(0))
  66            .map(|info| info.buffer_row)
  67            .collect::<Vec<_>>(),
  68        (0..buffer.read(cx).row_count())
  69            .map(Some)
  70            .collect::<Vec<_>>()
  71    );
  72    assert_consistent_line_numbers(&snapshot);
  73}
  74
  75#[gpui::test]
  76fn test_remote(cx: &mut App) {
  77    let host_buffer = cx.new(|cx| Buffer::local("a", cx));
  78    let guest_buffer = cx.new(|cx| {
  79        let state = host_buffer.read(cx).to_proto(cx);
  80        let ops = cx
  81            .background_executor()
  82            .block(host_buffer.read(cx).serialize_ops(None, cx));
  83        let mut buffer =
  84            Buffer::from_proto(ReplicaId::REMOTE_SERVER, Capability::ReadWrite, state, None)
  85                .unwrap();
  86        buffer.apply_ops(
  87            ops.into_iter()
  88                .map(|op| language::proto::deserialize_operation(op).unwrap()),
  89            cx,
  90        );
  91        buffer
  92    });
  93    let multibuffer = cx.new(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
  94    let snapshot = multibuffer.read(cx).snapshot(cx);
  95    assert_eq!(snapshot.text(), "a");
  96
  97    guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
  98    let snapshot = multibuffer.read(cx).snapshot(cx);
  99    assert_eq!(snapshot.text(), "ab");
 100
 101    guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
 102    let snapshot = multibuffer.read(cx).snapshot(cx);
 103    assert_eq!(snapshot.text(), "abc");
 104}
 105
 106#[gpui::test]
 107fn test_excerpt_boundaries_and_clipping(cx: &mut App) {
 108    let buffer_1 = cx.new(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
 109    let buffer_2 = cx.new(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
 110    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
 111
 112    let events = Arc::new(RwLock::new(Vec::<Event>::new()));
 113    multibuffer.update(cx, |_, cx| {
 114        let events = events.clone();
 115        cx.subscribe(&multibuffer, move |_, _, event, _| {
 116            if let Event::Edited { .. } = event {
 117                events.write().push(event.clone())
 118            }
 119        })
 120        .detach();
 121    });
 122
 123    let subscription = multibuffer.update(cx, |multibuffer, cx| {
 124        let subscription = multibuffer.subscribe();
 125        multibuffer.push_excerpts(
 126            buffer_1.clone(),
 127            [ExcerptRange::new(Point::new(1, 2)..Point::new(2, 5))],
 128            cx,
 129        );
 130        assert_eq!(
 131            subscription.consume().into_inner(),
 132            [Edit {
 133                old: MultiBufferOffset(0)..MultiBufferOffset(0),
 134                new: MultiBufferOffset(0)..MultiBufferOffset(10)
 135            }]
 136        );
 137
 138        multibuffer.push_excerpts(
 139            buffer_1.clone(),
 140            [ExcerptRange::new(Point::new(3, 3)..Point::new(4, 4))],
 141            cx,
 142        );
 143        multibuffer.push_excerpts(
 144            buffer_2.clone(),
 145            [ExcerptRange::new(Point::new(3, 1)..Point::new(3, 3))],
 146            cx,
 147        );
 148        assert_eq!(
 149            subscription.consume().into_inner(),
 150            [Edit {
 151                old: MultiBufferOffset(10)..MultiBufferOffset(10),
 152                new: MultiBufferOffset(10)..MultiBufferOffset(22)
 153            }]
 154        );
 155
 156        subscription
 157    });
 158
 159    // Adding excerpts emits an edited event.
 160    assert_eq!(
 161        events.read().as_slice(),
 162        &[
 163            Event::Edited {
 164                edited_buffer: None,
 165            },
 166            Event::Edited {
 167                edited_buffer: None,
 168            },
 169            Event::Edited {
 170                edited_buffer: None,
 171            }
 172        ]
 173    );
 174
 175    let snapshot = multibuffer.read(cx).snapshot(cx);
 176    assert_eq!(
 177        snapshot.text(),
 178        indoc!(
 179            "
 180            bbbb
 181            ccccc
 182            ddd
 183            eeee
 184            jj"
 185        ),
 186    );
 187    assert_eq!(
 188        snapshot
 189            .row_infos(MultiBufferRow(0))
 190            .map(|info| info.buffer_row)
 191            .collect::<Vec<_>>(),
 192        [Some(1), Some(2), Some(3), Some(4), Some(3)]
 193    );
 194    assert_eq!(
 195        snapshot
 196            .row_infos(MultiBufferRow(2))
 197            .map(|info| info.buffer_row)
 198            .collect::<Vec<_>>(),
 199        [Some(3), Some(4), Some(3)]
 200    );
 201    assert_eq!(
 202        snapshot
 203            .row_infos(MultiBufferRow(4))
 204            .map(|info| info.buffer_row)
 205            .collect::<Vec<_>>(),
 206        [Some(3)]
 207    );
 208    assert!(
 209        snapshot
 210            .row_infos(MultiBufferRow(5))
 211            .map(|info| info.buffer_row)
 212            .collect::<Vec<_>>()
 213            .is_empty()
 214    );
 215
 216    assert_eq!(
 217        boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
 218        &[
 219            (MultiBufferRow(0), "bbbb\nccccc".to_string(), true),
 220            (MultiBufferRow(2), "ddd\neeee".to_string(), false),
 221            (MultiBufferRow(4), "jj".to_string(), true),
 222        ]
 223    );
 224    assert_eq!(
 225        boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
 226        &[(MultiBufferRow(0), "bbbb\nccccc".to_string(), true)]
 227    );
 228    assert_eq!(
 229        boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
 230        &[]
 231    );
 232    assert_eq!(
 233        boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
 234        &[]
 235    );
 236    assert_eq!(
 237        boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
 238        &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
 239    );
 240    assert_eq!(
 241        boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
 242        &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
 243    );
 244    assert_eq!(
 245        boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
 246        &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
 247    );
 248    assert_eq!(
 249        boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
 250        &[(MultiBufferRow(4), "jj".to_string(), true)]
 251    );
 252    assert_eq!(
 253        boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
 254        &[]
 255    );
 256
 257    buffer_1.update(cx, |buffer, cx| {
 258        let text = "\n";
 259        buffer.edit(
 260            [
 261                (Point::new(0, 0)..Point::new(0, 0), text),
 262                (Point::new(2, 1)..Point::new(2, 3), text),
 263            ],
 264            None,
 265            cx,
 266        );
 267    });
 268
 269    let snapshot = multibuffer.read(cx).snapshot(cx);
 270    assert_eq!(
 271        snapshot.text(),
 272        concat!(
 273            "bbbb\n", // Preserve newlines
 274            "c\n",    //
 275            "cc\n",   //
 276            "ddd\n",  //
 277            "eeee\n", //
 278            "jj"      //
 279        )
 280    );
 281
 282    assert_eq!(
 283        subscription.consume().into_inner(),
 284        [Edit {
 285            old: MultiBufferOffset(6)..MultiBufferOffset(8),
 286            new: MultiBufferOffset(6)..MultiBufferOffset(7)
 287        }]
 288    );
 289
 290    let snapshot = multibuffer.read(cx).snapshot(cx);
 291    assert_eq!(
 292        snapshot.clip_point(Point::new(0, 5), Bias::Left),
 293        Point::new(0, 4)
 294    );
 295    assert_eq!(
 296        snapshot.clip_point(Point::new(0, 5), Bias::Right),
 297        Point::new(0, 4)
 298    );
 299    assert_eq!(
 300        snapshot.clip_point(Point::new(5, 1), Bias::Right),
 301        Point::new(5, 1)
 302    );
 303    assert_eq!(
 304        snapshot.clip_point(Point::new(5, 2), Bias::Right),
 305        Point::new(5, 2)
 306    );
 307    assert_eq!(
 308        snapshot.clip_point(Point::new(5, 3), Bias::Right),
 309        Point::new(5, 2)
 310    );
 311
 312    let snapshot = multibuffer.update(cx, |multibuffer, cx| {
 313        let (buffer_2_excerpt_id, _) =
 314            multibuffer.excerpts_for_buffer(buffer_2.read(cx).remote_id(), cx)[0].clone();
 315        multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
 316        multibuffer.snapshot(cx)
 317    });
 318
 319    assert_eq!(
 320        snapshot.text(),
 321        concat!(
 322            "bbbb\n", // Preserve newlines
 323            "c\n",    //
 324            "cc\n",   //
 325            "ddd\n",  //
 326            "eeee",   //
 327        )
 328    );
 329
 330    fn boundaries_in_range(
 331        range: Range<Point>,
 332        snapshot: &MultiBufferSnapshot,
 333    ) -> Vec<(MultiBufferRow, String, bool)> {
 334        snapshot
 335            .excerpt_boundaries_in_range(range)
 336            .map(|boundary| {
 337                let starts_new_buffer = boundary.starts_new_buffer();
 338                (
 339                    boundary.row,
 340                    boundary
 341                        .next
 342                        .buffer
 343                        .text_for_range(boundary.next.range.context)
 344                        .collect::<String>(),
 345                    starts_new_buffer,
 346                )
 347            })
 348            .collect::<Vec<_>>()
 349    }
 350}
 351
 352#[gpui::test]
 353async fn test_diff_boundary_anchors(cx: &mut TestAppContext) {
 354    let base_text = "one\ntwo\nthree\n";
 355    let text = "one\nthree\n";
 356    let buffer = cx.new(|cx| Buffer::local(text, cx));
 357    let diff = cx
 358        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
 359    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer, cx));
 360    multibuffer.update(cx, |multibuffer, cx| multibuffer.add_diff(diff, cx));
 361
 362    let (before, after) = multibuffer.update(cx, |multibuffer, cx| {
 363        let before = multibuffer.snapshot(cx).anchor_before(Point::new(1, 0));
 364        let after = multibuffer.snapshot(cx).anchor_after(Point::new(1, 0));
 365        multibuffer.set_all_diff_hunks_expanded(cx);
 366        (before, after)
 367    });
 368    cx.run_until_parked();
 369
 370    let snapshot = multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
 371    let actual_text = snapshot.text();
 372    let actual_row_infos = snapshot.row_infos(MultiBufferRow(0)).collect::<Vec<_>>();
 373    let actual_diff = format_diff(&actual_text, &actual_row_infos, &Default::default(), None);
 374    pretty_assertions::assert_eq!(
 375        actual_diff,
 376        indoc! {
 377            "  one
 378             - two
 379               three
 380             "
 381        },
 382    );
 383
 384    multibuffer.update(cx, |multibuffer, cx| {
 385        let snapshot = multibuffer.snapshot(cx);
 386        assert_eq!(before.to_point(&snapshot), Point::new(1, 0));
 387        assert_eq!(after.to_point(&snapshot), Point::new(2, 0));
 388        assert_eq!(
 389            vec![Point::new(1, 0), Point::new(2, 0),],
 390            snapshot.summaries_for_anchors::<Point, _>(&[before, after]),
 391        )
 392    })
 393}
 394
 395#[gpui::test]
 396async fn test_diff_hunks_in_range(cx: &mut TestAppContext) {
 397    let base_text = "one\ntwo\nthree\nfour\nfive\nsix\nseven\neight\n";
 398    let text = "one\nfour\nseven\n";
 399    let buffer = cx.new(|cx| Buffer::local(text, cx));
 400    let diff = cx
 401        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
 402    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer, cx));
 403    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
 404        (multibuffer.snapshot(cx), multibuffer.subscribe())
 405    });
 406
 407    multibuffer.update(cx, |multibuffer, cx| {
 408        multibuffer.add_diff(diff, cx);
 409        multibuffer.expand_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
 410    });
 411
 412    assert_new_snapshot(
 413        &multibuffer,
 414        &mut snapshot,
 415        &mut subscription,
 416        cx,
 417        indoc! {
 418            "  one
 419             - two
 420             - three
 421               four
 422             - five
 423             - six
 424               seven
 425             - eight
 426            "
 427        },
 428    );
 429
 430    assert_eq!(
 431        snapshot
 432            .diff_hunks_in_range(Point::new(1, 0)..Point::MAX)
 433            .map(|hunk| hunk.row_range.start.0..hunk.row_range.end.0)
 434            .collect::<Vec<_>>(),
 435        vec![1..3, 4..6, 7..8]
 436    );
 437
 438    assert_eq!(snapshot.diff_hunk_before(Point::new(1, 1)), None,);
 439    assert_eq!(
 440        snapshot.diff_hunk_before(Point::new(7, 0)),
 441        Some(MultiBufferRow(4))
 442    );
 443    assert_eq!(
 444        snapshot.diff_hunk_before(Point::new(4, 0)),
 445        Some(MultiBufferRow(1))
 446    );
 447
 448    multibuffer.update(cx, |multibuffer, cx| {
 449        multibuffer.collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
 450    });
 451
 452    assert_new_snapshot(
 453        &multibuffer,
 454        &mut snapshot,
 455        &mut subscription,
 456        cx,
 457        indoc! {
 458            "
 459            one
 460            four
 461            seven
 462            "
 463        },
 464    );
 465
 466    assert_eq!(
 467        snapshot.diff_hunk_before(Point::new(2, 0)),
 468        Some(MultiBufferRow(1)),
 469    );
 470    assert_eq!(
 471        snapshot.diff_hunk_before(Point::new(4, 0)),
 472        Some(MultiBufferRow(2))
 473    );
 474}
 475
 476#[gpui::test]
 477async fn test_inverted_diff_hunks_in_range(cx: &mut TestAppContext) {
 478    let base_text = "one\ntwo\nthree\nfour\nfive\nsix\nseven\neight\n";
 479    let text = "ZERO\none\nTHREE\nfour\nseven\nEIGHT\nNINE\n";
 480    let buffer = cx.new(|cx| Buffer::local(text, cx));
 481    let diff = cx
 482        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
 483    let base_text_buffer = diff.read_with(cx, |diff, _| diff.base_text_buffer());
 484    let multibuffer = cx.new(|cx| MultiBuffer::singleton(base_text_buffer.clone(), cx));
 485    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
 486        (multibuffer.snapshot(cx), multibuffer.subscribe())
 487    });
 488
 489    multibuffer.update(cx, |multibuffer, cx| {
 490        multibuffer.add_inverted_diff(diff, buffer.clone(), cx);
 491    });
 492
 493    assert_new_snapshot(
 494        &multibuffer,
 495        &mut snapshot,
 496        &mut subscription,
 497        cx,
 498        indoc! {
 499            "  one
 500             - two
 501             - three
 502               four
 503             - five
 504             - six
 505               seven
 506             - eight
 507            "
 508        },
 509    );
 510
 511    assert_eq!(
 512        snapshot
 513            .diff_hunks_in_range(Point::new(0, 0)..Point::MAX)
 514            .map(|hunk| hunk.row_range.start.0..hunk.row_range.end.0)
 515            .collect::<Vec<_>>(),
 516        vec![0..0, 1..3, 4..6, 7..8]
 517    );
 518
 519    assert_eq!(
 520        snapshot.diff_hunk_before(Point::new(1, 1)),
 521        Some(MultiBufferRow(0))
 522    );
 523    assert_eq!(
 524        snapshot.diff_hunk_before(Point::new(7, 0)),
 525        Some(MultiBufferRow(4))
 526    );
 527    assert_eq!(
 528        snapshot.diff_hunk_before(Point::new(4, 0)),
 529        Some(MultiBufferRow(1))
 530    );
 531}
 532
 533#[gpui::test]
 534async fn test_editing_text_in_diff_hunks(cx: &mut TestAppContext) {
 535    let base_text = "one\ntwo\nfour\nfive\nsix\nseven\n";
 536    let text = "one\ntwo\nTHREE\nfour\nfive\nseven\n";
 537    let buffer = cx.new(|cx| Buffer::local(text, cx));
 538    let diff = cx
 539        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
 540    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
 541
 542    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
 543        multibuffer.add_diff(diff.clone(), cx);
 544        (multibuffer.snapshot(cx), multibuffer.subscribe())
 545    });
 546
 547    cx.executor().run_until_parked();
 548    multibuffer.update(cx, |multibuffer, cx| {
 549        multibuffer.set_all_diff_hunks_expanded(cx);
 550    });
 551
 552    assert_new_snapshot(
 553        &multibuffer,
 554        &mut snapshot,
 555        &mut subscription,
 556        cx,
 557        indoc! {
 558            "
 559              one
 560              two
 561            + THREE
 562              four
 563              five
 564            - six
 565              seven
 566            "
 567        },
 568    );
 569
 570    // Insert a newline within an insertion hunk
 571    multibuffer.update(cx, |multibuffer, cx| {
 572        multibuffer.edit([(Point::new(2, 0)..Point::new(2, 0), "__\n__")], None, cx);
 573    });
 574    assert_new_snapshot(
 575        &multibuffer,
 576        &mut snapshot,
 577        &mut subscription,
 578        cx,
 579        indoc! {
 580            "
 581              one
 582              two
 583            + __
 584            + __THREE
 585              four
 586              five
 587            - six
 588              seven
 589            "
 590        },
 591    );
 592
 593    // Delete the newline before a deleted hunk.
 594    multibuffer.update(cx, |multibuffer, cx| {
 595        multibuffer.edit([(Point::new(5, 4)..Point::new(6, 0), "")], None, cx);
 596    });
 597    assert_new_snapshot(
 598        &multibuffer,
 599        &mut snapshot,
 600        &mut subscription,
 601        cx,
 602        indoc! {
 603            "
 604              one
 605              two
 606            + __
 607            + __THREE
 608              four
 609              fiveseven
 610            "
 611        },
 612    );
 613
 614    multibuffer.update(cx, |multibuffer, cx| multibuffer.undo(cx));
 615    assert_new_snapshot(
 616        &multibuffer,
 617        &mut snapshot,
 618        &mut subscription,
 619        cx,
 620        indoc! {
 621            "
 622              one
 623              two
 624            + __
 625            + __THREE
 626              four
 627              five
 628            - six
 629              seven
 630            "
 631        },
 632    );
 633
 634    // Cannot (yet) insert at the beginning of a deleted hunk.
 635    // (because it would put the newline in the wrong place)
 636    multibuffer.update(cx, |multibuffer, cx| {
 637        multibuffer.edit([(Point::new(6, 0)..Point::new(6, 0), "\n")], None, cx);
 638    });
 639    assert_new_snapshot(
 640        &multibuffer,
 641        &mut snapshot,
 642        &mut subscription,
 643        cx,
 644        indoc! {
 645            "
 646              one
 647              two
 648            + __
 649            + __THREE
 650              four
 651              five
 652            - six
 653              seven
 654            "
 655        },
 656    );
 657
 658    // Replace a range that ends in a deleted hunk.
 659    multibuffer.update(cx, |multibuffer, cx| {
 660        multibuffer.edit([(Point::new(5, 2)..Point::new(6, 2), "fty-")], None, cx);
 661    });
 662    assert_new_snapshot(
 663        &multibuffer,
 664        &mut snapshot,
 665        &mut subscription,
 666        cx,
 667        indoc! {
 668            "
 669              one
 670              two
 671            + __
 672            + __THREE
 673              four
 674              fifty-seven
 675            "
 676        },
 677    );
 678}
 679
 680#[gpui::test]
 681fn test_excerpt_events(cx: &mut App) {
 682    let buffer_1 = cx.new(|cx| Buffer::local(sample_text(10, 3, 'a'), cx));
 683    let buffer_2 = cx.new(|cx| Buffer::local(sample_text(10, 3, 'm'), cx));
 684
 685    let leader_multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
 686    let follower_multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
 687    let follower_edit_event_count = Arc::new(RwLock::new(0));
 688
 689    follower_multibuffer.update(cx, |_, cx| {
 690        let follower_edit_event_count = follower_edit_event_count.clone();
 691        cx.subscribe(
 692            &leader_multibuffer,
 693            move |follower, _, event, cx| match event.clone() {
 694                Event::ExcerptsAdded {
 695                    buffer,
 696                    predecessor,
 697                    excerpts,
 698                } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
 699                Event::ExcerptsRemoved { ids, .. } => follower.remove_excerpts(ids, cx),
 700                Event::Edited { .. } => {
 701                    *follower_edit_event_count.write() += 1;
 702                }
 703                _ => {}
 704            },
 705        )
 706        .detach();
 707    });
 708
 709    leader_multibuffer.update(cx, |leader, cx| {
 710        leader.push_excerpts(
 711            buffer_1.clone(),
 712            [ExcerptRange::new(0..8), ExcerptRange::new(12..16)],
 713            cx,
 714        );
 715        leader.insert_excerpts_after(
 716            leader.excerpt_ids()[0],
 717            buffer_2.clone(),
 718            [ExcerptRange::new(0..5), ExcerptRange::new(10..15)],
 719            cx,
 720        )
 721    });
 722    assert_eq!(
 723        leader_multibuffer.read(cx).snapshot(cx).text(),
 724        follower_multibuffer.read(cx).snapshot(cx).text(),
 725    );
 726    assert_eq!(*follower_edit_event_count.read(), 2);
 727
 728    leader_multibuffer.update(cx, |leader, cx| {
 729        let excerpt_ids = leader.excerpt_ids();
 730        leader.remove_excerpts([excerpt_ids[1], excerpt_ids[3]], cx);
 731    });
 732    assert_eq!(
 733        leader_multibuffer.read(cx).snapshot(cx).text(),
 734        follower_multibuffer.read(cx).snapshot(cx).text(),
 735    );
 736    assert_eq!(*follower_edit_event_count.read(), 3);
 737
 738    // Removing an empty set of excerpts is a noop.
 739    leader_multibuffer.update(cx, |leader, cx| {
 740        leader.remove_excerpts([], cx);
 741    });
 742    assert_eq!(
 743        leader_multibuffer.read(cx).snapshot(cx).text(),
 744        follower_multibuffer.read(cx).snapshot(cx).text(),
 745    );
 746    assert_eq!(*follower_edit_event_count.read(), 3);
 747
 748    // Adding an empty set of excerpts is a noop.
 749    leader_multibuffer.update(cx, |leader, cx| {
 750        leader.push_excerpts::<usize>(buffer_2.clone(), [], cx);
 751    });
 752    assert_eq!(
 753        leader_multibuffer.read(cx).snapshot(cx).text(),
 754        follower_multibuffer.read(cx).snapshot(cx).text(),
 755    );
 756    assert_eq!(*follower_edit_event_count.read(), 3);
 757
 758    leader_multibuffer.update(cx, |leader, cx| {
 759        leader.clear(cx);
 760    });
 761    assert_eq!(
 762        leader_multibuffer.read(cx).snapshot(cx).text(),
 763        follower_multibuffer.read(cx).snapshot(cx).text(),
 764    );
 765    assert_eq!(*follower_edit_event_count.read(), 4);
 766}
 767
 768#[gpui::test]
 769fn test_expand_excerpts(cx: &mut App) {
 770    let buffer = cx.new(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
 771    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
 772
 773    multibuffer.update(cx, |multibuffer, cx| {
 774        multibuffer.set_excerpts_for_path(
 775            PathKey::for_buffer(&buffer, cx),
 776            buffer,
 777            vec![
 778                // Note that in this test, this first excerpt
 779                // does not contain a new line
 780                Point::new(3, 2)..Point::new(3, 3),
 781                Point::new(7, 1)..Point::new(7, 3),
 782                Point::new(15, 0)..Point::new(15, 0),
 783            ],
 784            1,
 785            cx,
 786        )
 787    });
 788
 789    let snapshot = multibuffer.read(cx).snapshot(cx);
 790
 791    assert_eq!(
 792        snapshot.text(),
 793        concat!(
 794            "ccc\n", //
 795            "ddd\n", //
 796            "eee",   //
 797            "\n",    // End of excerpt
 798            "ggg\n", //
 799            "hhh\n", //
 800            "iii",   //
 801            "\n",    // End of excerpt
 802            "ooo\n", //
 803            "ppp\n", //
 804            "qqq",   // End of excerpt
 805        )
 806    );
 807    drop(snapshot);
 808
 809    multibuffer.update(cx, |multibuffer, cx| {
 810        let line_zero = multibuffer.snapshot(cx).anchor_before(Point::new(0, 0));
 811        multibuffer.expand_excerpts(
 812            multibuffer.excerpt_ids(),
 813            1,
 814            ExpandExcerptDirection::UpAndDown,
 815            cx,
 816        );
 817        let snapshot = multibuffer.snapshot(cx);
 818        let line_two = snapshot.anchor_before(Point::new(2, 0));
 819        assert_eq!(line_two.cmp(&line_zero, &snapshot), cmp::Ordering::Greater);
 820    });
 821
 822    let snapshot = multibuffer.read(cx).snapshot(cx);
 823
 824    assert_eq!(
 825        snapshot.text(),
 826        concat!(
 827            "bbb\n", //
 828            "ccc\n", //
 829            "ddd\n", //
 830            "eee\n", //
 831            "fff\n", //
 832            "ggg\n", //
 833            "hhh\n", //
 834            "iii\n", //
 835            "jjj\n", // End of excerpt
 836            "nnn\n", //
 837            "ooo\n", //
 838            "ppp\n", //
 839            "qqq\n", //
 840            "rrr",   // End of excerpt
 841        )
 842    );
 843}
 844
 845#[gpui::test(iterations = 100)]
 846async fn test_set_anchored_excerpts_for_path(cx: &mut TestAppContext) {
 847    let buffer_1 = cx.new(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
 848    let buffer_2 = cx.new(|cx| Buffer::local(sample_text(15, 4, 'a'), cx));
 849    let snapshot_1 = buffer_1.update(cx, |buffer, _| buffer.snapshot());
 850    let snapshot_2 = buffer_2.update(cx, |buffer, _| buffer.snapshot());
 851    let ranges_1 = vec![
 852        snapshot_1.anchor_before(Point::new(3, 2))..snapshot_1.anchor_before(Point::new(4, 2)),
 853        snapshot_1.anchor_before(Point::new(7, 1))..snapshot_1.anchor_before(Point::new(7, 3)),
 854        snapshot_1.anchor_before(Point::new(15, 0))..snapshot_1.anchor_before(Point::new(15, 0)),
 855    ];
 856    let ranges_2 = vec![
 857        snapshot_2.anchor_before(Point::new(2, 1))..snapshot_2.anchor_before(Point::new(3, 1)),
 858        snapshot_2.anchor_before(Point::new(10, 0))..snapshot_2.anchor_before(Point::new(10, 2)),
 859    ];
 860
 861    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
 862    let anchor_ranges_1 = multibuffer
 863        .update(cx, |multibuffer, cx| {
 864            multibuffer.set_anchored_excerpts_for_path(
 865                PathKey::for_buffer(&buffer_1, cx),
 866                buffer_1.clone(),
 867                ranges_1,
 868                2,
 869                cx,
 870            )
 871        })
 872        .await;
 873    let snapshot_1 = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
 874    assert_eq!(
 875        anchor_ranges_1
 876            .iter()
 877            .map(|range| range.to_point(&snapshot_1))
 878            .collect::<Vec<_>>(),
 879        vec![
 880            Point::new(2, 2)..Point::new(3, 2),
 881            Point::new(6, 1)..Point::new(6, 3),
 882            Point::new(11, 0)..Point::new(11, 0),
 883        ]
 884    );
 885    let anchor_ranges_2 = multibuffer
 886        .update(cx, |multibuffer, cx| {
 887            multibuffer.set_anchored_excerpts_for_path(
 888                PathKey::for_buffer(&buffer_2, cx),
 889                buffer_2.clone(),
 890                ranges_2,
 891                2,
 892                cx,
 893            )
 894        })
 895        .await;
 896    let snapshot_2 = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
 897    assert_eq!(
 898        anchor_ranges_2
 899            .iter()
 900            .map(|range| range.to_point(&snapshot_2))
 901            .collect::<Vec<_>>(),
 902        vec![
 903            Point::new(16, 1)..Point::new(17, 1),
 904            Point::new(22, 0)..Point::new(22, 2)
 905        ]
 906    );
 907
 908    let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
 909    assert_eq!(
 910        snapshot.text(),
 911        concat!(
 912            "bbb\n", // buffer_1
 913            "ccc\n", //
 914            "ddd\n", // <-- excerpt 1
 915            "eee\n", // <-- excerpt 1
 916            "fff\n", //
 917            "ggg\n", //
 918            "hhh\n", // <-- excerpt 2
 919            "iii\n", //
 920            "jjj\n", //
 921            //
 922            "nnn\n", //
 923            "ooo\n", //
 924            "ppp\n", // <-- excerpt 3
 925            "qqq\n", //
 926            "rrr\n", //
 927            //
 928            "aaaa\n", // buffer 2
 929            "bbbb\n", //
 930            "cccc\n", // <-- excerpt 4
 931            "dddd\n", // <-- excerpt 4
 932            "eeee\n", //
 933            "ffff\n", //
 934            //
 935            "iiii\n", //
 936            "jjjj\n", //
 937            "kkkk\n", // <-- excerpt 5
 938            "llll\n", //
 939            "mmmm",   //
 940        )
 941    );
 942}
 943
 944#[gpui::test]
 945fn test_empty_multibuffer(cx: &mut App) {
 946    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
 947
 948    let snapshot = multibuffer.read(cx).snapshot(cx);
 949    assert_eq!(snapshot.text(), "");
 950    assert_eq!(
 951        snapshot
 952            .row_infos(MultiBufferRow(0))
 953            .map(|info| info.buffer_row)
 954            .collect::<Vec<_>>(),
 955        &[Some(0)]
 956    );
 957    assert!(
 958        snapshot
 959            .row_infos(MultiBufferRow(1))
 960            .map(|info| info.buffer_row)
 961            .collect::<Vec<_>>()
 962            .is_empty(),
 963    );
 964}
 965
 966#[gpui::test]
 967async fn test_empty_diff_excerpt(cx: &mut TestAppContext) {
 968    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
 969    let buffer = cx.new(|cx| Buffer::local("", cx));
 970    let base_text = "a\nb\nc";
 971
 972    let diff = cx
 973        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
 974    multibuffer.update(cx, |multibuffer, cx| {
 975        multibuffer.push_excerpts(buffer.clone(), [ExcerptRange::new(0..0)], cx);
 976        multibuffer.set_all_diff_hunks_expanded(cx);
 977        multibuffer.add_diff(diff.clone(), cx);
 978    });
 979    cx.run_until_parked();
 980
 981    let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
 982    assert_eq!(snapshot.text(), "a\nb\nc\n");
 983
 984    let hunk = snapshot
 985        .diff_hunks_in_range(Point::new(1, 1)..Point::new(1, 1))
 986        .next()
 987        .unwrap();
 988
 989    assert_eq!(hunk.diff_base_byte_range.start, BufferOffset(0));
 990
 991    let buf2 = cx.new(|cx| Buffer::local("X", cx));
 992    multibuffer.update(cx, |multibuffer, cx| {
 993        multibuffer.push_excerpts(buf2, [ExcerptRange::new(0..1)], cx);
 994    });
 995
 996    buffer.update(cx, |buffer, cx| {
 997        buffer.edit([(0..0, "a\nb\nc")], None, cx);
 998        diff.update(cx, |diff, cx| {
 999            diff.recalculate_diff_sync(&buffer.text_snapshot(), cx);
1000        });
1001        assert_eq!(buffer.text(), "a\nb\nc")
1002    });
1003    cx.run_until_parked();
1004
1005    let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
1006    assert_eq!(snapshot.text(), "a\nb\nc\nX");
1007
1008    buffer.update(cx, |buffer, cx| {
1009        buffer.undo(cx);
1010        diff.update(cx, |diff, cx| {
1011            diff.recalculate_diff_sync(&buffer.text_snapshot(), cx);
1012        });
1013        assert_eq!(buffer.text(), "")
1014    });
1015    cx.run_until_parked();
1016
1017    let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
1018    assert_eq!(snapshot.text(), "a\nb\nc\n\nX");
1019}
1020
1021#[gpui::test]
1022fn test_singleton_multibuffer_anchors(cx: &mut App) {
1023    let buffer = cx.new(|cx| Buffer::local("abcd", cx));
1024    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
1025    let old_snapshot = multibuffer.read(cx).snapshot(cx);
1026    buffer.update(cx, |buffer, cx| {
1027        buffer.edit([(0..0, "X")], None, cx);
1028        buffer.edit([(5..5, "Y")], None, cx);
1029    });
1030    let new_snapshot = multibuffer.read(cx).snapshot(cx);
1031
1032    assert_eq!(old_snapshot.text(), "abcd");
1033    assert_eq!(new_snapshot.text(), "XabcdY");
1034
1035    assert_eq!(
1036        old_snapshot
1037            .anchor_before(MultiBufferOffset(0))
1038            .to_offset(&new_snapshot),
1039        MultiBufferOffset(0)
1040    );
1041    assert_eq!(
1042        old_snapshot
1043            .anchor_after(MultiBufferOffset(0))
1044            .to_offset(&new_snapshot),
1045        MultiBufferOffset(1)
1046    );
1047    assert_eq!(
1048        old_snapshot
1049            .anchor_before(MultiBufferOffset(4))
1050            .to_offset(&new_snapshot),
1051        MultiBufferOffset(5)
1052    );
1053    assert_eq!(
1054        old_snapshot
1055            .anchor_after(MultiBufferOffset(4))
1056            .to_offset(&new_snapshot),
1057        MultiBufferOffset(6)
1058    );
1059}
1060
1061#[gpui::test]
1062fn test_multibuffer_anchors(cx: &mut App) {
1063    let buffer_1 = cx.new(|cx| Buffer::local("abcd", cx));
1064    let buffer_2 = cx.new(|cx| Buffer::local("efghi", cx));
1065    let multibuffer = cx.new(|cx| {
1066        let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
1067        multibuffer.push_excerpts(buffer_1.clone(), [ExcerptRange::new(0..4)], cx);
1068        multibuffer.push_excerpts(buffer_2.clone(), [ExcerptRange::new(0..5)], cx);
1069        multibuffer
1070    });
1071    let old_snapshot = multibuffer.read(cx).snapshot(cx);
1072
1073    assert_eq!(
1074        old_snapshot
1075            .anchor_before(MultiBufferOffset(0))
1076            .to_offset(&old_snapshot),
1077        MultiBufferOffset(0)
1078    );
1079    assert_eq!(
1080        old_snapshot
1081            .anchor_after(MultiBufferOffset(0))
1082            .to_offset(&old_snapshot),
1083        MultiBufferOffset(0)
1084    );
1085    assert_eq!(Anchor::min().to_offset(&old_snapshot), MultiBufferOffset(0));
1086    assert_eq!(Anchor::min().to_offset(&old_snapshot), MultiBufferOffset(0));
1087    assert_eq!(
1088        Anchor::max().to_offset(&old_snapshot),
1089        MultiBufferOffset(10)
1090    );
1091    assert_eq!(
1092        Anchor::max().to_offset(&old_snapshot),
1093        MultiBufferOffset(10)
1094    );
1095
1096    buffer_1.update(cx, |buffer, cx| {
1097        buffer.edit([(0..0, "W")], None, cx);
1098        buffer.edit([(5..5, "X")], None, cx);
1099    });
1100    buffer_2.update(cx, |buffer, cx| {
1101        buffer.edit([(0..0, "Y")], None, cx);
1102        buffer.edit([(6..6, "Z")], None, cx);
1103    });
1104    let new_snapshot = multibuffer.read(cx).snapshot(cx);
1105
1106    assert_eq!(old_snapshot.text(), "abcd\nefghi");
1107    assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
1108
1109    assert_eq!(
1110        old_snapshot
1111            .anchor_before(MultiBufferOffset(0))
1112            .to_offset(&new_snapshot),
1113        MultiBufferOffset(0)
1114    );
1115    assert_eq!(
1116        old_snapshot
1117            .anchor_after(MultiBufferOffset(0))
1118            .to_offset(&new_snapshot),
1119        MultiBufferOffset(1)
1120    );
1121    assert_eq!(
1122        old_snapshot
1123            .anchor_before(MultiBufferOffset(1))
1124            .to_offset(&new_snapshot),
1125        MultiBufferOffset(2)
1126    );
1127    assert_eq!(
1128        old_snapshot
1129            .anchor_after(MultiBufferOffset(1))
1130            .to_offset(&new_snapshot),
1131        MultiBufferOffset(2)
1132    );
1133    assert_eq!(
1134        old_snapshot
1135            .anchor_before(MultiBufferOffset(2))
1136            .to_offset(&new_snapshot),
1137        MultiBufferOffset(3)
1138    );
1139    assert_eq!(
1140        old_snapshot
1141            .anchor_after(MultiBufferOffset(2))
1142            .to_offset(&new_snapshot),
1143        MultiBufferOffset(3)
1144    );
1145    assert_eq!(
1146        old_snapshot
1147            .anchor_before(MultiBufferOffset(5))
1148            .to_offset(&new_snapshot),
1149        MultiBufferOffset(7)
1150    );
1151    assert_eq!(
1152        old_snapshot
1153            .anchor_after(MultiBufferOffset(5))
1154            .to_offset(&new_snapshot),
1155        MultiBufferOffset(8)
1156    );
1157    assert_eq!(
1158        old_snapshot
1159            .anchor_before(MultiBufferOffset(10))
1160            .to_offset(&new_snapshot),
1161        MultiBufferOffset(13)
1162    );
1163    assert_eq!(
1164        old_snapshot
1165            .anchor_after(MultiBufferOffset(10))
1166            .to_offset(&new_snapshot),
1167        MultiBufferOffset(14)
1168    );
1169}
1170
1171#[gpui::test]
1172fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut App) {
1173    let buffer_1 = cx.new(|cx| Buffer::local("abcd", cx));
1174    let buffer_2 = cx.new(|cx| Buffer::local("ABCDEFGHIJKLMNOP", cx));
1175    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
1176
1177    // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
1178    // Add an excerpt from buffer 1 that spans this new insertion.
1179    buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
1180    let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
1181        multibuffer
1182            .push_excerpts(buffer_1.clone(), [ExcerptRange::new(0..7)], cx)
1183            .pop()
1184            .unwrap()
1185    });
1186
1187    let snapshot_1 = multibuffer.read(cx).snapshot(cx);
1188    assert_eq!(snapshot_1.text(), "abcd123");
1189
1190    // Replace the buffer 1 excerpt with new excerpts from buffer 2.
1191    let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
1192        multibuffer.remove_excerpts([excerpt_id_1], cx);
1193        let mut ids = multibuffer
1194            .push_excerpts(
1195                buffer_2.clone(),
1196                [
1197                    ExcerptRange::new(0..4),
1198                    ExcerptRange::new(6..10),
1199                    ExcerptRange::new(12..16),
1200                ],
1201                cx,
1202            )
1203            .into_iter();
1204        (ids.next().unwrap(), ids.next().unwrap())
1205    });
1206    let snapshot_2 = multibuffer.read(cx).snapshot(cx);
1207    assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
1208
1209    // The old excerpt id doesn't get reused.
1210    assert_ne!(excerpt_id_2, excerpt_id_1);
1211
1212    // Resolve some anchors from the previous snapshot in the new snapshot.
1213    // The current excerpts are from a different buffer, so we don't attempt to
1214    // resolve the old text anchor in the new buffer.
1215    assert_eq!(
1216        snapshot_2.summary_for_anchor::<MultiBufferOffset>(
1217            &snapshot_1.anchor_before(MultiBufferOffset(2))
1218        ),
1219        MultiBufferOffset(0)
1220    );
1221    assert_eq!(
1222        snapshot_2.summaries_for_anchors::<MultiBufferOffset, _>(&[
1223            snapshot_1.anchor_before(MultiBufferOffset(2)),
1224            snapshot_1.anchor_after(MultiBufferOffset(3))
1225        ]),
1226        vec![MultiBufferOffset(0), MultiBufferOffset(0)]
1227    );
1228
1229    // Refresh anchors from the old snapshot. The return value indicates that both
1230    // anchors lost their original excerpt.
1231    let refresh = snapshot_2.refresh_anchors(&[
1232        snapshot_1.anchor_before(MultiBufferOffset(2)),
1233        snapshot_1.anchor_after(MultiBufferOffset(3)),
1234    ]);
1235    assert_eq!(
1236        refresh,
1237        &[
1238            (0, snapshot_2.anchor_before(MultiBufferOffset(0)), false),
1239            (1, snapshot_2.anchor_after(MultiBufferOffset(0)), false),
1240        ]
1241    );
1242
1243    // Replace the middle excerpt with a smaller excerpt in buffer 2,
1244    // that intersects the old excerpt.
1245    let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
1246        multibuffer.remove_excerpts([excerpt_id_3], cx);
1247        multibuffer
1248            .insert_excerpts_after(
1249                excerpt_id_2,
1250                buffer_2.clone(),
1251                [ExcerptRange::new(5..8)],
1252                cx,
1253            )
1254            .pop()
1255            .unwrap()
1256    });
1257
1258    let snapshot_3 = multibuffer.read(cx).snapshot(cx);
1259    assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
1260    assert_ne!(excerpt_id_5, excerpt_id_3);
1261
1262    // Resolve some anchors from the previous snapshot in the new snapshot.
1263    // The third anchor can't be resolved, since its excerpt has been removed,
1264    // so it resolves to the same position as its predecessor.
1265    let anchors = [
1266        snapshot_2.anchor_before(MultiBufferOffset(0)),
1267        snapshot_2.anchor_after(MultiBufferOffset(2)),
1268        snapshot_2.anchor_after(MultiBufferOffset(6)),
1269        snapshot_2.anchor_after(MultiBufferOffset(14)),
1270    ];
1271    assert_eq!(
1272        snapshot_3.summaries_for_anchors::<MultiBufferOffset, _>(&anchors),
1273        &[
1274            MultiBufferOffset(0),
1275            MultiBufferOffset(2),
1276            MultiBufferOffset(9),
1277            MultiBufferOffset(13)
1278        ]
1279    );
1280
1281    let new_anchors = snapshot_3.refresh_anchors(&anchors);
1282    assert_eq!(
1283        new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
1284        &[(0, true), (1, true), (2, true), (3, true)]
1285    );
1286    assert_eq!(
1287        snapshot_3.summaries_for_anchors::<MultiBufferOffset, _>(new_anchors.iter().map(|a| &a.1)),
1288        &[
1289            MultiBufferOffset(0),
1290            MultiBufferOffset(2),
1291            MultiBufferOffset(7),
1292            MultiBufferOffset(13)
1293        ]
1294    );
1295}
1296
1297#[gpui::test]
1298async fn test_basic_diff_hunks(cx: &mut TestAppContext) {
1299    let text = indoc!(
1300        "
1301        ZERO
1302        one
1303        TWO
1304        three
1305        six
1306        "
1307    );
1308    let base_text = indoc!(
1309        "
1310        one
1311        two
1312        three
1313        four
1314        five
1315        six
1316        "
1317    );
1318
1319    let buffer = cx.new(|cx| Buffer::local(text, cx));
1320    let diff = cx
1321        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
1322    cx.run_until_parked();
1323
1324    let multibuffer = cx.new(|cx| {
1325        let mut multibuffer = MultiBuffer::singleton(buffer.clone(), cx);
1326        multibuffer.add_diff(diff.clone(), cx);
1327        multibuffer
1328    });
1329
1330    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
1331        (multibuffer.snapshot(cx), multibuffer.subscribe())
1332    });
1333    assert_eq!(
1334        snapshot.text(),
1335        indoc!(
1336            "
1337            ZERO
1338            one
1339            TWO
1340            three
1341            six
1342            "
1343        ),
1344    );
1345
1346    multibuffer.update(cx, |multibuffer, cx| {
1347        multibuffer.expand_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
1348    });
1349
1350    assert_new_snapshot(
1351        &multibuffer,
1352        &mut snapshot,
1353        &mut subscription,
1354        cx,
1355        indoc!(
1356            "
1357            + ZERO
1358              one
1359            - two
1360            + TWO
1361              three
1362            - four
1363            - five
1364              six
1365            "
1366        ),
1367    );
1368
1369    assert_eq!(
1370        snapshot
1371            .row_infos(MultiBufferRow(0))
1372            .map(|info| (info.buffer_row, info.diff_status))
1373            .collect::<Vec<_>>(),
1374        vec![
1375            (Some(0), Some(DiffHunkStatus::added_none())),
1376            (Some(1), None),
1377            (Some(1), Some(DiffHunkStatus::deleted_none())),
1378            (Some(2), Some(DiffHunkStatus::added_none())),
1379            (Some(3), None),
1380            (Some(3), Some(DiffHunkStatus::deleted_none())),
1381            (Some(4), Some(DiffHunkStatus::deleted_none())),
1382            (Some(4), None),
1383            (Some(5), None)
1384        ]
1385    );
1386
1387    assert_chunks_in_ranges(&snapshot);
1388    assert_consistent_line_numbers(&snapshot);
1389    assert_position_translation(&snapshot);
1390    assert_line_indents(&snapshot);
1391
1392    multibuffer.update(cx, |multibuffer, cx| {
1393        multibuffer.collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], cx)
1394    });
1395    assert_new_snapshot(
1396        &multibuffer,
1397        &mut snapshot,
1398        &mut subscription,
1399        cx,
1400        indoc!(
1401            "
1402            ZERO
1403            one
1404            TWO
1405            three
1406            six
1407            "
1408        ),
1409    );
1410
1411    assert_chunks_in_ranges(&snapshot);
1412    assert_consistent_line_numbers(&snapshot);
1413    assert_position_translation(&snapshot);
1414    assert_line_indents(&snapshot);
1415
1416    // Expand the first diff hunk
1417    multibuffer.update(cx, |multibuffer, cx| {
1418        let position = multibuffer.read(cx).anchor_before(Point::new(2, 2));
1419        multibuffer.expand_diff_hunks(vec![position..position], cx)
1420    });
1421    assert_new_snapshot(
1422        &multibuffer,
1423        &mut snapshot,
1424        &mut subscription,
1425        cx,
1426        indoc!(
1427            "
1428              ZERO
1429              one
1430            - two
1431            + TWO
1432              three
1433              six
1434            "
1435        ),
1436    );
1437
1438    // Expand the second diff hunk
1439    multibuffer.update(cx, |multibuffer, cx| {
1440        let start = multibuffer.read(cx).anchor_before(Point::new(4, 0));
1441        let end = multibuffer.read(cx).anchor_before(Point::new(5, 0));
1442        multibuffer.expand_diff_hunks(vec![start..end], cx)
1443    });
1444    assert_new_snapshot(
1445        &multibuffer,
1446        &mut snapshot,
1447        &mut subscription,
1448        cx,
1449        indoc!(
1450            "
1451              ZERO
1452              one
1453            - two
1454            + TWO
1455              three
1456            - four
1457            - five
1458              six
1459            "
1460        ),
1461    );
1462
1463    assert_chunks_in_ranges(&snapshot);
1464    assert_consistent_line_numbers(&snapshot);
1465    assert_position_translation(&snapshot);
1466    assert_line_indents(&snapshot);
1467
1468    // Edit the buffer before the first hunk
1469    buffer.update(cx, |buffer, cx| {
1470        buffer.edit_via_marked_text(
1471            indoc!(
1472                "
1473                ZERO
1474                one« hundred
1475                  thousand»
1476                TWO
1477                three
1478                six
1479                "
1480            ),
1481            None,
1482            cx,
1483        );
1484    });
1485    assert_new_snapshot(
1486        &multibuffer,
1487        &mut snapshot,
1488        &mut subscription,
1489        cx,
1490        indoc!(
1491            "
1492              ZERO
1493              one hundred
1494                thousand
1495            - two
1496            + TWO
1497              three
1498            - four
1499            - five
1500              six
1501            "
1502        ),
1503    );
1504
1505    assert_chunks_in_ranges(&snapshot);
1506    assert_consistent_line_numbers(&snapshot);
1507    assert_position_translation(&snapshot);
1508    assert_line_indents(&snapshot);
1509
1510    // Recalculate the diff, changing the first diff hunk.
1511    diff.update(cx, |diff, cx| {
1512        diff.recalculate_diff_sync(&buffer.read(cx).text_snapshot(), cx);
1513    });
1514    cx.run_until_parked();
1515    assert_new_snapshot(
1516        &multibuffer,
1517        &mut snapshot,
1518        &mut subscription,
1519        cx,
1520        indoc!(
1521            "
1522              ZERO
1523              one hundred
1524                thousand
1525              TWO
1526              three
1527            - four
1528            - five
1529              six
1530            "
1531        ),
1532    );
1533
1534    assert_eq!(
1535        snapshot
1536            .diff_hunks_in_range(MultiBufferOffset(0)..snapshot.len())
1537            .map(|hunk| hunk.row_range.start.0..hunk.row_range.end.0)
1538            .collect::<Vec<_>>(),
1539        &[0..4, 5..7]
1540    );
1541}
1542
1543#[gpui::test]
1544async fn test_repeatedly_expand_a_diff_hunk(cx: &mut TestAppContext) {
1545    let text = indoc!(
1546        "
1547        one
1548        TWO
1549        THREE
1550        four
1551        FIVE
1552        six
1553        "
1554    );
1555    let base_text = indoc!(
1556        "
1557        one
1558        four
1559        five
1560        six
1561        "
1562    );
1563
1564    let buffer = cx.new(|cx| Buffer::local(text, cx));
1565    let diff = cx
1566        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
1567    cx.run_until_parked();
1568
1569    let multibuffer = cx.new(|cx| {
1570        let mut multibuffer = MultiBuffer::singleton(buffer.clone(), cx);
1571        multibuffer.add_diff(diff.clone(), cx);
1572        multibuffer
1573    });
1574
1575    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
1576        (multibuffer.snapshot(cx), multibuffer.subscribe())
1577    });
1578
1579    multibuffer.update(cx, |multibuffer, cx| {
1580        multibuffer.expand_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
1581    });
1582
1583    assert_new_snapshot(
1584        &multibuffer,
1585        &mut snapshot,
1586        &mut subscription,
1587        cx,
1588        indoc!(
1589            "
1590              one
1591            + TWO
1592            + THREE
1593              four
1594            - five
1595            + FIVE
1596              six
1597            "
1598        ),
1599    );
1600
1601    // Regression test: expanding diff hunks that are already expanded should not change anything.
1602    multibuffer.update(cx, |multibuffer, cx| {
1603        multibuffer.expand_diff_hunks(
1604            vec![
1605                snapshot.anchor_before(Point::new(2, 0))..snapshot.anchor_before(Point::new(2, 0)),
1606            ],
1607            cx,
1608        );
1609    });
1610
1611    assert_new_snapshot(
1612        &multibuffer,
1613        &mut snapshot,
1614        &mut subscription,
1615        cx,
1616        indoc!(
1617            "
1618              one
1619            + TWO
1620            + THREE
1621              four
1622            - five
1623            + FIVE
1624              six
1625            "
1626        ),
1627    );
1628
1629    // Now collapse all diff hunks
1630    multibuffer.update(cx, |multibuffer, cx| {
1631        multibuffer.collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
1632    });
1633
1634    assert_new_snapshot(
1635        &multibuffer,
1636        &mut snapshot,
1637        &mut subscription,
1638        cx,
1639        indoc!(
1640            "
1641            one
1642            TWO
1643            THREE
1644            four
1645            FIVE
1646            six
1647            "
1648        ),
1649    );
1650
1651    // Expand the hunks again, but this time provide two ranges that are both within the same hunk
1652    // Target the first hunk which is between "one" and "four"
1653    multibuffer.update(cx, |multibuffer, cx| {
1654        multibuffer.expand_diff_hunks(
1655            vec![
1656                snapshot.anchor_before(Point::new(4, 0))..snapshot.anchor_before(Point::new(4, 0)),
1657                snapshot.anchor_before(Point::new(4, 2))..snapshot.anchor_before(Point::new(4, 2)),
1658            ],
1659            cx,
1660        );
1661    });
1662    assert_new_snapshot(
1663        &multibuffer,
1664        &mut snapshot,
1665        &mut subscription,
1666        cx,
1667        indoc!(
1668            "
1669              one
1670              TWO
1671              THREE
1672              four
1673            - five
1674            + FIVE
1675              six
1676            "
1677        ),
1678    );
1679}
1680
1681#[gpui::test]
1682fn test_set_excerpts_for_buffer_ordering(cx: &mut TestAppContext) {
1683    let buf1 = cx.new(|cx| {
1684        Buffer::local(
1685            indoc! {
1686            "zero
1687            one
1688            two
1689            two.five
1690            three
1691            four
1692            five
1693            six
1694            seven
1695            eight
1696            nine
1697            ten
1698            eleven
1699            ",
1700            },
1701            cx,
1702        )
1703    });
1704    let path1: PathKey = PathKey::with_sort_prefix(0, rel_path("root").into_arc());
1705
1706    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
1707    multibuffer.update(cx, |multibuffer, cx| {
1708        multibuffer.set_excerpts_for_path(
1709            path1.clone(),
1710            buf1.clone(),
1711            vec![
1712                Point::row_range(1..2),
1713                Point::row_range(6..7),
1714                Point::row_range(11..12),
1715            ],
1716            1,
1717            cx,
1718        );
1719    });
1720
1721    assert_excerpts_match(
1722        &multibuffer,
1723        cx,
1724        indoc! {
1725            "-----
1726            zero
1727            one
1728            two
1729            two.five
1730            -----
1731            four
1732            five
1733            six
1734            seven
1735            -----
1736            nine
1737            ten
1738            eleven
1739            "
1740        },
1741    );
1742
1743    buf1.update(cx, |buffer, cx| buffer.edit([(0..5, "")], None, cx));
1744
1745    multibuffer.update(cx, |multibuffer, cx| {
1746        multibuffer.set_excerpts_for_path(
1747            path1.clone(),
1748            buf1.clone(),
1749            vec![
1750                Point::row_range(0..3),
1751                Point::row_range(5..7),
1752                Point::row_range(10..11),
1753            ],
1754            1,
1755            cx,
1756        );
1757    });
1758
1759    assert_excerpts_match(
1760        &multibuffer,
1761        cx,
1762        indoc! {
1763            "-----
1764             one
1765             two
1766             two.five
1767             three
1768             four
1769             five
1770             six
1771             seven
1772             eight
1773             nine
1774             ten
1775             eleven
1776            "
1777        },
1778    );
1779}
1780
1781#[gpui::test]
1782fn test_set_excerpts_for_buffer(cx: &mut TestAppContext) {
1783    let buf1 = cx.new(|cx| {
1784        Buffer::local(
1785            indoc! {
1786            "zero
1787            one
1788            two
1789            three
1790            four
1791            five
1792            six
1793            seven
1794            ",
1795            },
1796            cx,
1797        )
1798    });
1799    let path1: PathKey = PathKey::with_sort_prefix(0, rel_path("root").into_arc());
1800    let buf2 = cx.new(|cx| {
1801        Buffer::local(
1802            indoc! {
1803            "000
1804            111
1805            222
1806            333
1807            444
1808            555
1809            666
1810            777
1811            888
1812            999
1813            "
1814            },
1815            cx,
1816        )
1817    });
1818    let path2 = PathKey::with_sort_prefix(1, rel_path("root").into_arc());
1819
1820    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
1821    multibuffer.update(cx, |multibuffer, cx| {
1822        multibuffer.set_excerpts_for_path(
1823            path1.clone(),
1824            buf1.clone(),
1825            vec![Point::row_range(0..1)],
1826            2,
1827            cx,
1828        );
1829    });
1830
1831    assert_excerpts_match(
1832        &multibuffer,
1833        cx,
1834        indoc! {
1835        "-----
1836        zero
1837        one
1838        two
1839        three
1840        "
1841        },
1842    );
1843
1844    multibuffer.update(cx, |multibuffer, cx| {
1845        multibuffer.set_excerpts_for_path(path1.clone(), buf1.clone(), vec![], 2, cx);
1846    });
1847
1848    assert_excerpts_match(&multibuffer, cx, "");
1849
1850    multibuffer.update(cx, |multibuffer, cx| {
1851        multibuffer.set_excerpts_for_path(
1852            path1.clone(),
1853            buf1.clone(),
1854            vec![Point::row_range(0..1), Point::row_range(7..8)],
1855            2,
1856            cx,
1857        );
1858    });
1859
1860    assert_excerpts_match(
1861        &multibuffer,
1862        cx,
1863        indoc! {"-----
1864                zero
1865                one
1866                two
1867                three
1868                -----
1869                five
1870                six
1871                seven
1872                "},
1873    );
1874
1875    multibuffer.update(cx, |multibuffer, cx| {
1876        multibuffer.set_excerpts_for_path(
1877            path1.clone(),
1878            buf1.clone(),
1879            vec![Point::row_range(0..1), Point::row_range(5..6)],
1880            2,
1881            cx,
1882        );
1883    });
1884
1885    assert_excerpts_match(
1886        &multibuffer,
1887        cx,
1888        indoc! {"-----
1889                    zero
1890                    one
1891                    two
1892                    three
1893                    four
1894                    five
1895                    six
1896                    seven
1897                    "},
1898    );
1899
1900    multibuffer.update(cx, |multibuffer, cx| {
1901        multibuffer.set_excerpts_for_path(
1902            path2.clone(),
1903            buf2.clone(),
1904            vec![Point::row_range(2..3)],
1905            2,
1906            cx,
1907        );
1908    });
1909
1910    assert_excerpts_match(
1911        &multibuffer,
1912        cx,
1913        indoc! {"-----
1914                zero
1915                one
1916                two
1917                three
1918                four
1919                five
1920                six
1921                seven
1922                -----
1923                000
1924                111
1925                222
1926                333
1927                444
1928                555
1929                "},
1930    );
1931
1932    multibuffer.update(cx, |multibuffer, cx| {
1933        multibuffer.set_excerpts_for_path(path1.clone(), buf1.clone(), vec![], 2, cx);
1934    });
1935
1936    multibuffer.update(cx, |multibuffer, cx| {
1937        multibuffer.set_excerpts_for_path(
1938            path1.clone(),
1939            buf1.clone(),
1940            vec![Point::row_range(3..4)],
1941            2,
1942            cx,
1943        );
1944    });
1945
1946    assert_excerpts_match(
1947        &multibuffer,
1948        cx,
1949        indoc! {"-----
1950                one
1951                two
1952                three
1953                four
1954                five
1955                six
1956                -----
1957                000
1958                111
1959                222
1960                333
1961                444
1962                555
1963                "},
1964    );
1965
1966    multibuffer.update(cx, |multibuffer, cx| {
1967        multibuffer.set_excerpts_for_path(
1968            path1.clone(),
1969            buf1.clone(),
1970            vec![Point::row_range(3..4)],
1971            2,
1972            cx,
1973        );
1974    });
1975}
1976
1977#[gpui::test]
1978fn test_set_excerpts_for_buffer_rename(cx: &mut TestAppContext) {
1979    let buf1 = cx.new(|cx| {
1980        Buffer::local(
1981            indoc! {
1982            "zero
1983            one
1984            two
1985            three
1986            four
1987            five
1988            six
1989            seven
1990            ",
1991            },
1992            cx,
1993        )
1994    });
1995    let path: PathKey = PathKey::with_sort_prefix(0, rel_path("root").into_arc());
1996    let buf2 = cx.new(|cx| {
1997        Buffer::local(
1998            indoc! {
1999            "000
2000            111
2001            222
2002            333
2003            "
2004            },
2005            cx,
2006        )
2007    });
2008
2009    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
2010    multibuffer.update(cx, |multibuffer, cx| {
2011        multibuffer.set_excerpts_for_path(
2012            path.clone(),
2013            buf1.clone(),
2014            vec![Point::row_range(1..1), Point::row_range(4..5)],
2015            1,
2016            cx,
2017        );
2018    });
2019
2020    assert_excerpts_match(
2021        &multibuffer,
2022        cx,
2023        indoc! {
2024        "-----
2025        zero
2026        one
2027        two
2028        three
2029        four
2030        five
2031        six
2032        "
2033        },
2034    );
2035
2036    multibuffer.update(cx, |multibuffer, cx| {
2037        multibuffer.set_excerpts_for_path(
2038            path.clone(),
2039            buf2.clone(),
2040            vec![Point::row_range(0..1)],
2041            2,
2042            cx,
2043        );
2044    });
2045
2046    assert_excerpts_match(
2047        &multibuffer,
2048        cx,
2049        indoc! {"-----
2050                000
2051                111
2052                222
2053                333
2054                "},
2055    );
2056}
2057
2058#[gpui::test]
2059async fn test_diff_hunks_with_multiple_excerpts(cx: &mut TestAppContext) {
2060    let base_text_1 = indoc!(
2061        "
2062        one
2063        two
2064            three
2065        four
2066        five
2067        six
2068        "
2069    );
2070    let text_1 = indoc!(
2071        "
2072        ZERO
2073        one
2074        TWO
2075            three
2076        six
2077        "
2078    );
2079    let base_text_2 = indoc!(
2080        "
2081        seven
2082          eight
2083        nine
2084        ten
2085        eleven
2086        twelve
2087        "
2088    );
2089    let text_2 = indoc!(
2090        "
2091          eight
2092        nine
2093        eleven
2094        THIRTEEN
2095        FOURTEEN
2096        "
2097    );
2098
2099    let buffer_1 = cx.new(|cx| Buffer::local(text_1, cx));
2100    let buffer_2 = cx.new(|cx| Buffer::local(text_2, cx));
2101    let diff_1 = cx.new(|cx| {
2102        BufferDiff::new_with_base_text(base_text_1, &buffer_1.read(cx).text_snapshot(), cx)
2103    });
2104    let diff_2 = cx.new(|cx| {
2105        BufferDiff::new_with_base_text(base_text_2, &buffer_2.read(cx).text_snapshot(), cx)
2106    });
2107    cx.run_until_parked();
2108
2109    let multibuffer = cx.new(|cx| {
2110        let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
2111        multibuffer.push_excerpts(
2112            buffer_1.clone(),
2113            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
2114            cx,
2115        );
2116        multibuffer.push_excerpts(
2117            buffer_2.clone(),
2118            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
2119            cx,
2120        );
2121        multibuffer.add_diff(diff_1.clone(), cx);
2122        multibuffer.add_diff(diff_2.clone(), cx);
2123        multibuffer
2124    });
2125
2126    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
2127        (multibuffer.snapshot(cx), multibuffer.subscribe())
2128    });
2129    assert_eq!(
2130        snapshot.text(),
2131        indoc!(
2132            "
2133            ZERO
2134            one
2135            TWO
2136                three
2137            six
2138
2139              eight
2140            nine
2141            eleven
2142            THIRTEEN
2143            FOURTEEN
2144            "
2145        ),
2146    );
2147
2148    multibuffer.update(cx, |multibuffer, cx| {
2149        multibuffer.expand_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
2150    });
2151
2152    assert_new_snapshot(
2153        &multibuffer,
2154        &mut snapshot,
2155        &mut subscription,
2156        cx,
2157        indoc!(
2158            "
2159            + ZERO
2160              one
2161            - two
2162            + TWO
2163                  three
2164            - four
2165            - five
2166              six
2167
2168            - seven
2169                eight
2170              nine
2171            - ten
2172              eleven
2173            - twelve
2174            + THIRTEEN
2175            + FOURTEEN
2176            "
2177        ),
2178    );
2179
2180    let id_1 = buffer_1.read_with(cx, |buffer, _| buffer.remote_id());
2181    let id_2 = buffer_2.read_with(cx, |buffer, _| buffer.remote_id());
2182    let base_id_1 = diff_1.read_with(cx, |diff, cx| diff.base_text(cx).remote_id());
2183    let base_id_2 = diff_2.read_with(cx, |diff, cx| diff.base_text(cx).remote_id());
2184
2185    let buffer_lines = (0..=snapshot.max_row().0)
2186        .map(|row| {
2187            let (buffer, range) = snapshot.buffer_line_for_row(MultiBufferRow(row))?;
2188            Some((
2189                buffer.remote_id(),
2190                buffer.text_for_range(range).collect::<String>(),
2191            ))
2192        })
2193        .collect::<Vec<_>>();
2194    pretty_assertions::assert_eq!(
2195        buffer_lines,
2196        [
2197            Some((id_1, "ZERO".into())),
2198            Some((id_1, "one".into())),
2199            Some((base_id_1, "two".into())),
2200            Some((id_1, "TWO".into())),
2201            Some((id_1, "    three".into())),
2202            Some((base_id_1, "four".into())),
2203            Some((base_id_1, "five".into())),
2204            Some((id_1, "six".into())),
2205            Some((id_1, "".into())),
2206            Some((base_id_2, "seven".into())),
2207            Some((id_2, "  eight".into())),
2208            Some((id_2, "nine".into())),
2209            Some((base_id_2, "ten".into())),
2210            Some((id_2, "eleven".into())),
2211            Some((base_id_2, "twelve".into())),
2212            Some((id_2, "THIRTEEN".into())),
2213            Some((id_2, "FOURTEEN".into())),
2214            Some((id_2, "".into())),
2215        ]
2216    );
2217
2218    let buffer_ids_by_range = [
2219        (Point::new(0, 0)..Point::new(0, 0), &[id_1] as &[_]),
2220        (Point::new(0, 0)..Point::new(2, 0), &[id_1]),
2221        (Point::new(2, 0)..Point::new(2, 0), &[id_1]),
2222        (Point::new(3, 0)..Point::new(3, 0), &[id_1]),
2223        (Point::new(8, 0)..Point::new(9, 0), &[id_1]),
2224        (Point::new(8, 0)..Point::new(10, 0), &[id_1, id_2]),
2225        (Point::new(9, 0)..Point::new(9, 0), &[id_2]),
2226    ];
2227    for (range, buffer_ids) in buffer_ids_by_range {
2228        assert_eq!(
2229            snapshot
2230                .buffer_ids_for_range(range.clone())
2231                .collect::<Vec<_>>(),
2232            buffer_ids,
2233            "buffer_ids_for_range({range:?}"
2234        );
2235    }
2236
2237    assert_position_translation(&snapshot);
2238    assert_line_indents(&snapshot);
2239
2240    assert_eq!(
2241        snapshot
2242            .diff_hunks_in_range(MultiBufferOffset(0)..snapshot.len())
2243            .map(|hunk| hunk.row_range.start.0..hunk.row_range.end.0)
2244            .collect::<Vec<_>>(),
2245        &[0..1, 2..4, 5..7, 9..10, 12..13, 14..17]
2246    );
2247
2248    buffer_2.update(cx, |buffer, cx| {
2249        buffer.edit_via_marked_text(
2250            indoc!(
2251                "
2252                  eight
2253                «»eleven
2254                THIRTEEN
2255                FOURTEEN
2256                "
2257            ),
2258            None,
2259            cx,
2260        );
2261    });
2262
2263    assert_new_snapshot(
2264        &multibuffer,
2265        &mut snapshot,
2266        &mut subscription,
2267        cx,
2268        indoc!(
2269            "
2270            + ZERO
2271              one
2272            - two
2273            + TWO
2274                  three
2275            - four
2276            - five
2277              six
2278
2279            - seven
2280                eight
2281              eleven
2282            - twelve
2283            + THIRTEEN
2284            + FOURTEEN
2285            "
2286        ),
2287    );
2288
2289    assert_line_indents(&snapshot);
2290}
2291
2292/// A naive implementation of a multi-buffer that does not maintain
2293/// any derived state, used for comparison in a randomized test.
2294#[derive(Default)]
2295struct ReferenceMultibuffer {
2296    excerpts: Vec<ReferenceExcerpt>,
2297    diffs: HashMap<BufferId, Entity<BufferDiff>>,
2298    inverted_diffs: HashMap<BufferId, (Entity<BufferDiff>, text::BufferSnapshot)>,
2299}
2300
2301#[derive(Debug)]
2302struct ReferenceExcerpt {
2303    id: ExcerptId,
2304    buffer: Entity<Buffer>,
2305    range: Range<text::Anchor>,
2306    expanded_diff_hunks: Vec<text::Anchor>,
2307}
2308
2309#[derive(Debug)]
2310struct ReferenceRegion {
2311    buffer_id: Option<BufferId>,
2312    range: Range<usize>,
2313    buffer_range: Option<Range<Point>>,
2314    status: Option<DiffHunkStatus>,
2315    excerpt_id: Option<ExcerptId>,
2316}
2317
2318impl ReferenceMultibuffer {
2319    fn expand_excerpts(&mut self, excerpts: &HashSet<ExcerptId>, line_count: u32, cx: &App) {
2320        if line_count == 0 {
2321            return;
2322        }
2323
2324        for id in excerpts {
2325            let excerpt = self.excerpts.iter_mut().find(|e| e.id == *id).unwrap();
2326            let snapshot = excerpt.buffer.read(cx).snapshot();
2327            let mut point_range = excerpt.range.to_point(&snapshot);
2328            point_range.start = Point::new(point_range.start.row.saturating_sub(line_count), 0);
2329            point_range.end =
2330                snapshot.clip_point(Point::new(point_range.end.row + line_count, 0), Bias::Left);
2331            point_range.end.column = snapshot.line_len(point_range.end.row);
2332            excerpt.range =
2333                snapshot.anchor_before(point_range.start)..snapshot.anchor_after(point_range.end);
2334        }
2335    }
2336
2337    fn remove_excerpt(&mut self, id: ExcerptId, cx: &App) {
2338        let ix = self
2339            .excerpts
2340            .iter()
2341            .position(|excerpt| excerpt.id == id)
2342            .unwrap();
2343        let excerpt = self.excerpts.remove(ix);
2344        let buffer = excerpt.buffer.read(cx);
2345        let id = buffer.remote_id();
2346        log::info!(
2347            "Removing excerpt {}: {:?}",
2348            ix,
2349            buffer
2350                .text_for_range(excerpt.range.to_offset(buffer))
2351                .collect::<String>(),
2352        );
2353        if !self
2354            .excerpts
2355            .iter()
2356            .any(|excerpt| excerpt.buffer.read(cx).remote_id() == id)
2357        {
2358            self.diffs.remove(&id);
2359            self.inverted_diffs.remove(&id);
2360        }
2361    }
2362
2363    fn insert_excerpt_after(
2364        &mut self,
2365        prev_id: ExcerptId,
2366        new_excerpt_id: ExcerptId,
2367        (buffer_handle, anchor_range): (Entity<Buffer>, Range<text::Anchor>),
2368    ) {
2369        let excerpt_ix = if prev_id == ExcerptId::max() {
2370            self.excerpts.len()
2371        } else {
2372            self.excerpts
2373                .iter()
2374                .position(|excerpt| excerpt.id == prev_id)
2375                .unwrap()
2376                + 1
2377        };
2378        self.excerpts.insert(
2379            excerpt_ix,
2380            ReferenceExcerpt {
2381                id: new_excerpt_id,
2382                buffer: buffer_handle,
2383                range: anchor_range,
2384                expanded_diff_hunks: Vec::new(),
2385            },
2386        );
2387    }
2388
2389    fn expand_diff_hunks(&mut self, excerpt_id: ExcerptId, range: Range<text::Anchor>, cx: &App) {
2390        let excerpt = self
2391            .excerpts
2392            .iter_mut()
2393            .find(|e| e.id == excerpt_id)
2394            .unwrap();
2395        let buffer = excerpt.buffer.read(cx).snapshot();
2396        let buffer_id = buffer.remote_id();
2397
2398        // Skip inverted excerpts - hunks are always expanded
2399        if self.inverted_diffs.contains_key(&buffer_id) {
2400            return;
2401        }
2402
2403        let Some(diff) = self.diffs.get(&buffer_id) else {
2404            return;
2405        };
2406        let excerpt_range = excerpt.range.to_offset(&buffer);
2407        for hunk in diff
2408            .read(cx)
2409            .snapshot(cx)
2410            .hunks_intersecting_range(range, &buffer)
2411        {
2412            let hunk_range = hunk.buffer_range.to_offset(&buffer);
2413            if hunk_range.start < excerpt_range.start || hunk_range.start > excerpt_range.end {
2414                continue;
2415            }
2416            if let Err(ix) = excerpt
2417                .expanded_diff_hunks
2418                .binary_search_by(|anchor| anchor.cmp(&hunk.buffer_range.start, &buffer))
2419            {
2420                log::info!(
2421                    "expanding diff hunk {:?}. excerpt:{:?}, excerpt range:{:?}",
2422                    hunk_range,
2423                    excerpt_id,
2424                    excerpt_range
2425                );
2426                excerpt
2427                    .expanded_diff_hunks
2428                    .insert(ix, hunk.buffer_range.start);
2429            } else {
2430                log::trace!("hunk {hunk_range:?} already expanded in excerpt {excerpt_id:?}");
2431            }
2432        }
2433    }
2434
2435    fn expected_content(&self, cx: &App) -> (String, Vec<RowInfo>, HashSet<MultiBufferRow>) {
2436        let mut text = String::new();
2437        let mut regions = Vec::<ReferenceRegion>::new();
2438        let mut excerpt_boundary_rows = HashSet::default();
2439        for excerpt in &self.excerpts {
2440            excerpt_boundary_rows.insert(MultiBufferRow(text.matches('\n').count() as u32));
2441            let buffer = excerpt.buffer.read(cx);
2442            let buffer_id = buffer.remote_id();
2443            let buffer_range = excerpt.range.to_offset(buffer);
2444
2445            if let Some((diff, main_buffer_snapshot)) = self.inverted_diffs.get(&buffer_id) {
2446                // INVERTED DIFF: Show base text with deleted regions marked
2447                let diff_snapshot = diff.read(cx).snapshot(cx);
2448
2449                let mut offset = buffer_range.start;
2450                for hunk in diff_snapshot
2451                    .hunks_intersecting_base_text_range(buffer_range.clone(), main_buffer_snapshot)
2452                {
2453                    let hunk_base_range = hunk.diff_base_byte_range.clone();
2454
2455                    // Match actual multibuffer behavior: skip hunks that start before excerpt
2456                    if hunk_base_range.start < buffer_range.start {
2457                        continue;
2458                    }
2459
2460                    // Clamp to excerpt range
2461                    let hunk_start = hunk_base_range.start.max(buffer_range.start);
2462                    let hunk_end = hunk_base_range.end.min(buffer_range.end);
2463
2464                    if hunk_start > buffer_range.end {
2465                        continue;
2466                    }
2467
2468                    // Add buffer text before the hunk (no status)
2469                    if hunk_start > offset {
2470                        let len = text.len();
2471                        text.extend(buffer.text_for_range(offset..hunk_start));
2472                        if text.len() > len {
2473                            regions.push(ReferenceRegion {
2474                                buffer_id: Some(buffer_id),
2475                                range: len..text.len(),
2476                                buffer_range: Some((offset..hunk_start).to_point(&buffer)),
2477                                status: None,
2478                                excerpt_id: Some(excerpt.id),
2479                            });
2480                        }
2481                    }
2482
2483                    // Add the "deleted" region (base text that's not in main)
2484                    if hunk_end > hunk_start {
2485                        let len = text.len();
2486                        text.extend(buffer.text_for_range(hunk_start..hunk_end));
2487                        regions.push(ReferenceRegion {
2488                            buffer_id: Some(buffer_id),
2489                            range: len..text.len(),
2490                            buffer_range: Some((hunk_start..hunk_end).to_point(&buffer)),
2491                            status: Some(DiffHunkStatus::deleted(hunk.secondary_status)),
2492                            excerpt_id: Some(excerpt.id),
2493                        });
2494                    }
2495
2496                    offset = hunk_end.max(offset);
2497                }
2498
2499                // Add remaining buffer text
2500                if offset < buffer_range.end {
2501                    let len = text.len();
2502                    text.extend(buffer.text_for_range(offset..buffer_range.end));
2503                    text.push('\n');
2504                    regions.push(ReferenceRegion {
2505                        buffer_id: Some(buffer_id),
2506                        range: len..text.len(),
2507                        buffer_range: Some((offset..buffer_range.end).to_point(&buffer)),
2508                        status: None,
2509                        excerpt_id: Some(excerpt.id),
2510                    });
2511                } else {
2512                    text.push('\n');
2513                    regions.push(ReferenceRegion {
2514                        buffer_id: Some(buffer_id),
2515                        range: text.len() - 1..text.len(),
2516                        buffer_range: Some((buffer_range.end..buffer_range.end).to_point(&buffer)),
2517                        status: None,
2518                        excerpt_id: Some(excerpt.id),
2519                    });
2520                }
2521            } else {
2522                // NON-INVERTED: Existing logic (show main buffer, insert deleted content)
2523                let diff = self.diffs.get(&buffer_id).unwrap().read(cx).snapshot(cx);
2524                let base_buffer = diff.base_text();
2525
2526                let mut offset = buffer_range.start;
2527                let hunks = diff
2528                    .hunks_intersecting_range(excerpt.range.clone(), buffer)
2529                    .peekable();
2530
2531                for hunk in hunks {
2532                    // Ignore hunks that are outside the excerpt range.
2533                    let mut hunk_range = hunk.buffer_range.to_offset(buffer);
2534
2535                    hunk_range.end = hunk_range.end.min(buffer_range.end);
2536                    if hunk_range.start > buffer_range.end || hunk_range.start < buffer_range.start
2537                    {
2538                        log::trace!("skipping hunk outside excerpt range");
2539                        continue;
2540                    }
2541
2542                    if !excerpt.expanded_diff_hunks.iter().any(|expanded_anchor| {
2543                        expanded_anchor.to_offset(buffer).max(buffer_range.start)
2544                            == hunk_range.start.max(buffer_range.start)
2545                    }) {
2546                        log::trace!("skipping a hunk that's not marked as expanded");
2547                        continue;
2548                    }
2549
2550                    if !hunk.buffer_range.start.is_valid(buffer) {
2551                        log::trace!("skipping hunk with deleted start: {:?}", hunk.range);
2552                        continue;
2553                    }
2554
2555                    if hunk_range.start >= offset {
2556                        // Add the buffer text before the hunk
2557                        let len = text.len();
2558                        text.extend(buffer.text_for_range(offset..hunk_range.start));
2559                        if text.len() > len {
2560                            regions.push(ReferenceRegion {
2561                                buffer_id: Some(buffer_id),
2562                                range: len..text.len(),
2563                                buffer_range: Some((offset..hunk_range.start).to_point(&buffer)),
2564                                status: None,
2565                                excerpt_id: Some(excerpt.id),
2566                            });
2567                        }
2568
2569                        // Add the deleted text for the hunk.
2570                        if !hunk.diff_base_byte_range.is_empty() {
2571                            let mut base_text = base_buffer
2572                                .text_for_range(hunk.diff_base_byte_range.clone())
2573                                .collect::<String>();
2574                            if !base_text.ends_with('\n') {
2575                                base_text.push('\n');
2576                            }
2577                            let len = text.len();
2578                            text.push_str(&base_text);
2579                            regions.push(ReferenceRegion {
2580                                buffer_id: Some(base_buffer.remote_id()),
2581                                range: len..text.len(),
2582                                buffer_range: Some(
2583                                    hunk.diff_base_byte_range.to_point(&base_buffer),
2584                                ),
2585                                status: Some(DiffHunkStatus::deleted(hunk.secondary_status)),
2586                                excerpt_id: Some(excerpt.id),
2587                            });
2588                        }
2589
2590                        offset = hunk_range.start;
2591                    }
2592
2593                    // Add the inserted text for the hunk.
2594                    if hunk_range.end > offset {
2595                        let len = text.len();
2596                        text.extend(buffer.text_for_range(offset..hunk_range.end));
2597                        let range = len..text.len();
2598                        let region = ReferenceRegion {
2599                            buffer_id: Some(buffer_id),
2600                            range,
2601                            buffer_range: Some((offset..hunk_range.end).to_point(&buffer)),
2602                            status: Some(DiffHunkStatus::added(hunk.secondary_status)),
2603                            excerpt_id: Some(excerpt.id),
2604                        };
2605                        offset = hunk_range.end;
2606                        regions.push(region);
2607                    }
2608                }
2609
2610                // Add the buffer text for the rest of the excerpt.
2611                let len = text.len();
2612                text.extend(buffer.text_for_range(offset..buffer_range.end));
2613                text.push('\n');
2614                regions.push(ReferenceRegion {
2615                    buffer_id: Some(buffer_id),
2616                    range: len..text.len(),
2617                    buffer_range: Some((offset..buffer_range.end).to_point(&buffer)),
2618                    status: None,
2619                    excerpt_id: Some(excerpt.id),
2620                });
2621            }
2622        }
2623
2624        // Remove final trailing newline.
2625        if self.excerpts.is_empty() {
2626            regions.push(ReferenceRegion {
2627                buffer_id: None,
2628                range: 0..1,
2629                buffer_range: Some(Point::new(0, 0)..Point::new(0, 1)),
2630                status: None,
2631                excerpt_id: None,
2632            });
2633        } else {
2634            text.pop();
2635        }
2636
2637        // Retrieve the row info using the region that contains
2638        // the start of each multi-buffer line.
2639        let mut ix = 0;
2640        let row_infos = text
2641            .split('\n')
2642            .map(|line| {
2643                let row_info = regions
2644                    .iter()
2645                    .position(|region| region.range.contains(&ix))
2646                    .map_or(RowInfo::default(), |region_ix| {
2647                        let region = &regions[region_ix];
2648                        let buffer_row = region.buffer_range.as_ref().map(|buffer_range| {
2649                            buffer_range.start.row
2650                                + text[region.range.start..ix].matches('\n').count() as u32
2651                        });
2652                        let main_buffer = self
2653                            .excerpts
2654                            .iter()
2655                            .find(|e| e.id == region.excerpt_id.unwrap())
2656                            .map(|e| e.buffer.clone());
2657                        let is_excerpt_start = region_ix == 0
2658                            || &regions[region_ix - 1].excerpt_id != &region.excerpt_id
2659                            || regions[region_ix - 1].range.is_empty();
2660                        let mut is_excerpt_end = region_ix == regions.len() - 1
2661                            || &regions[region_ix + 1].excerpt_id != &region.excerpt_id;
2662                        let is_start = !text[region.range.start..ix].contains('\n');
2663                        let mut is_end = if region.range.end > text.len() {
2664                            !text[ix..].contains('\n')
2665                        } else {
2666                            text[ix..region.range.end.min(text.len())]
2667                                .matches('\n')
2668                                .count()
2669                                == 1
2670                        };
2671                        if region_ix < regions.len() - 1
2672                            && !text[ix..].contains("\n")
2673                            && (region.status == Some(DiffHunkStatus::added_none())
2674                                || region.status.is_some_and(|s| s.is_deleted()))
2675                            && regions[region_ix + 1].excerpt_id == region.excerpt_id
2676                            && regions[region_ix + 1].range.start == text.len()
2677                        {
2678                            is_end = true;
2679                            is_excerpt_end = true;
2680                        }
2681                        let multibuffer_row =
2682                            MultiBufferRow(text[..ix].matches('\n').count() as u32);
2683                        let mut expand_direction = None;
2684                        if let Some(buffer) = &main_buffer {
2685                            let buffer_row = buffer_row.unwrap();
2686                            let needs_expand_up = is_excerpt_start && is_start && buffer_row > 0;
2687                            let needs_expand_down = is_excerpt_end
2688                                && is_end
2689                                && buffer.read(cx).max_point().row > buffer_row;
2690                            expand_direction = if needs_expand_up && needs_expand_down {
2691                                Some(ExpandExcerptDirection::UpAndDown)
2692                            } else if needs_expand_up {
2693                                Some(ExpandExcerptDirection::Up)
2694                            } else if needs_expand_down {
2695                                Some(ExpandExcerptDirection::Down)
2696                            } else {
2697                                None
2698                            };
2699                        }
2700                        RowInfo {
2701                            buffer_id: region.buffer_id,
2702                            diff_status: region.status,
2703                            buffer_row,
2704                            wrapped_buffer_row: None,
2705
2706                            multibuffer_row: Some(multibuffer_row),
2707                            expand_info: expand_direction.zip(region.excerpt_id).map(
2708                                |(direction, excerpt_id)| ExpandInfo {
2709                                    direction,
2710                                    excerpt_id,
2711                                },
2712                            ),
2713                        }
2714                    });
2715                ix += line.len() + 1;
2716                row_info
2717            })
2718            .collect();
2719
2720        (text, row_infos, excerpt_boundary_rows)
2721    }
2722
2723    fn diffs_updated(&mut self, cx: &App) {
2724        for excerpt in &mut self.excerpts {
2725            let buffer = excerpt.buffer.read(cx).snapshot();
2726            let buffer_id = buffer.remote_id();
2727
2728            // Skip inverted diff excerpts - hunks are always expanded
2729            if self.inverted_diffs.contains_key(&buffer_id) {
2730                continue;
2731            }
2732
2733            let excerpt_range = excerpt.range.to_offset(&buffer);
2734            let Some(diff) = self.diffs.get(&buffer_id) else {
2735                continue;
2736            };
2737            let diff = diff.read(cx).snapshot(cx);
2738            let mut hunks = diff.hunks_in_row_range(0..u32::MAX, &buffer).peekable();
2739            excerpt.expanded_diff_hunks.retain(|hunk_anchor| {
2740                if !hunk_anchor.is_valid(&buffer) {
2741                    return false;
2742                }
2743                while let Some(hunk) = hunks.peek() {
2744                    match hunk.buffer_range.start.cmp(hunk_anchor, &buffer) {
2745                        cmp::Ordering::Less => {
2746                            hunks.next();
2747                        }
2748                        cmp::Ordering::Equal => {
2749                            let hunk_range = hunk.buffer_range.to_offset(&buffer);
2750                            return hunk_range.end >= excerpt_range.start
2751                                && hunk_range.start <= excerpt_range.end;
2752                        }
2753                        cmp::Ordering::Greater => break,
2754                    }
2755                }
2756                false
2757            });
2758        }
2759    }
2760
2761    fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut App) {
2762        let buffer_id = diff.read(cx).buffer_id;
2763        self.diffs.insert(buffer_id, diff);
2764    }
2765
2766    fn add_inverted_diff(
2767        &mut self,
2768        diff: Entity<BufferDiff>,
2769        main_buffer_snapshot: text::BufferSnapshot,
2770        cx: &App,
2771    ) {
2772        let base_text_buffer_id = diff.read(cx).base_text(cx).remote_id();
2773        self.inverted_diffs
2774            .insert(base_text_buffer_id, (diff, main_buffer_snapshot));
2775    }
2776
2777    fn update_inverted_diff_snapshot(
2778        &mut self,
2779        diff: &Entity<BufferDiff>,
2780        main_buffer_snapshot: text::BufferSnapshot,
2781        cx: &App,
2782    ) {
2783        let base_text_buffer_id = diff.read(cx).base_text(cx).remote_id();
2784        if let Some((_, stored_snapshot)) = self.inverted_diffs.get_mut(&base_text_buffer_id) {
2785            *stored_snapshot = main_buffer_snapshot;
2786        }
2787    }
2788}
2789
2790#[gpui::test(iterations = 100)]
2791async fn test_random_set_ranges(cx: &mut TestAppContext, mut rng: StdRng) {
2792    let base_text = "a\n".repeat(100);
2793    let buf = cx.update(|cx| cx.new(|cx| Buffer::local(base_text, cx)));
2794    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
2795
2796    let operations = env::var("OPERATIONS")
2797        .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
2798        .unwrap_or(10);
2799
2800    fn row_ranges(ranges: &Vec<Range<Point>>) -> Vec<Range<u32>> {
2801        ranges
2802            .iter()
2803            .map(|range| range.start.row..range.end.row)
2804            .collect()
2805    }
2806
2807    for _ in 0..operations {
2808        let snapshot = buf.update(cx, |buf, _| buf.snapshot());
2809        let num_ranges = rng.random_range(0..=10);
2810        let max_row = snapshot.max_point().row;
2811        let mut ranges = (0..num_ranges)
2812            .map(|_| {
2813                let start = rng.random_range(0..max_row);
2814                let end = rng.random_range(start + 1..max_row + 1);
2815                Point::row_range(start..end)
2816            })
2817            .collect::<Vec<_>>();
2818        ranges.sort_by_key(|range| range.start);
2819        log::info!("Setting ranges: {:?}", row_ranges(&ranges));
2820        let (created, _) = multibuffer.update(cx, |multibuffer, cx| {
2821            multibuffer.set_excerpts_for_path(
2822                PathKey::for_buffer(&buf, cx),
2823                buf.clone(),
2824                ranges.clone(),
2825                2,
2826                cx,
2827            )
2828        });
2829
2830        assert_eq!(created.len(), ranges.len());
2831
2832        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
2833        let mut last_end = None;
2834        let mut seen_ranges = Vec::default();
2835
2836        for (_, buf, range) in snapshot.excerpts() {
2837            let start = range.context.start.to_point(buf);
2838            let end = range.context.end.to_point(buf);
2839            seen_ranges.push(start..end);
2840
2841            if let Some(last_end) = last_end.take() {
2842                assert!(
2843                    start > last_end,
2844                    "multibuffer has out-of-order ranges: {:?}; {:?} <= {:?}",
2845                    row_ranges(&seen_ranges),
2846                    start,
2847                    last_end
2848                )
2849            }
2850
2851            ranges.retain(|range| range.start < start || range.end > end);
2852
2853            last_end = Some(end)
2854        }
2855
2856        assert!(
2857            ranges.is_empty(),
2858            "multibuffer {:?} did not include all ranges: {:?}",
2859            row_ranges(&seen_ranges),
2860            row_ranges(&ranges)
2861        );
2862    }
2863}
2864
2865#[gpui::test(iterations = 100)]
2866async fn test_random_multibuffer(cx: &mut TestAppContext, mut rng: StdRng) {
2867    let operations = env::var("OPERATIONS")
2868        .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
2869        .unwrap_or(10);
2870    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
2871    let mut buffers: Vec<Entity<Buffer>> = Vec::new();
2872    let mut base_texts: HashMap<BufferId, String> = HashMap::default();
2873    let mut reference = ReferenceMultibuffer::default();
2874    let mut anchors = Vec::new();
2875    let mut old_versions = Vec::new();
2876    let mut needs_diff_calculation = false;
2877    // Maps main_buffer_id -> diff for inverted diffs (needed for recalculation when main buffer is edited)
2878    let mut inverted_diff_main_buffers: HashMap<BufferId, Entity<BufferDiff>> = HashMap::default();
2879    for _ in 0..operations {
2880        match rng.random_range(0..100) {
2881            0..=14 if !buffers.is_empty() => {
2882                let buffer = buffers.choose(&mut rng).unwrap();
2883                buffer.update(cx, |buf, cx| {
2884                    let edit_count = rng.random_range(1..5);
2885                    buf.randomly_edit(&mut rng, edit_count, cx);
2886                    log::info!("buffer text:\n{}", buf.text());
2887                    needs_diff_calculation = true;
2888                });
2889                cx.update(|cx| reference.diffs_updated(cx));
2890            }
2891            15..=19 if !reference.excerpts.is_empty() => {
2892                multibuffer.update(cx, |multibuffer, cx| {
2893                    let ids = multibuffer.excerpt_ids();
2894                    let mut excerpts = HashSet::default();
2895                    for _ in 0..rng.random_range(0..ids.len()) {
2896                        excerpts.extend(ids.choose(&mut rng).copied());
2897                    }
2898
2899                    let line_count = rng.random_range(0..5);
2900
2901                    let excerpt_ixs = excerpts
2902                        .iter()
2903                        .map(|id| reference.excerpts.iter().position(|e| e.id == *id).unwrap())
2904                        .collect::<Vec<_>>();
2905                    log::info!("Expanding excerpts {excerpt_ixs:?} by {line_count} lines");
2906                    multibuffer.expand_excerpts(
2907                        excerpts.iter().cloned(),
2908                        line_count,
2909                        ExpandExcerptDirection::UpAndDown,
2910                        cx,
2911                    );
2912
2913                    reference.expand_excerpts(&excerpts, line_count, cx);
2914                });
2915            }
2916            20..=29 if !reference.excerpts.is_empty() => {
2917                let mut ids_to_remove = vec![];
2918                for _ in 0..rng.random_range(1..=3) {
2919                    let Some(excerpt) = reference.excerpts.choose(&mut rng) else {
2920                        break;
2921                    };
2922                    let id = excerpt.id;
2923                    cx.update(|cx| reference.remove_excerpt(id, cx));
2924                    ids_to_remove.push(id);
2925                }
2926                let snapshot =
2927                    multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
2928                ids_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
2929                drop(snapshot);
2930                multibuffer.update(cx, |multibuffer, cx| {
2931                    multibuffer.remove_excerpts(ids_to_remove, cx)
2932                });
2933            }
2934            30..=39 if !reference.excerpts.is_empty() => {
2935                let multibuffer =
2936                    multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
2937                let offset = multibuffer.clip_offset(
2938                    MultiBufferOffset(rng.random_range(0..=multibuffer.len().0)),
2939                    Bias::Left,
2940                );
2941                let bias = if rng.random() {
2942                    Bias::Left
2943                } else {
2944                    Bias::Right
2945                };
2946                log::info!("Creating anchor at {} with bias {:?}", offset.0, bias);
2947                anchors.push(multibuffer.anchor_at(offset, bias));
2948                anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
2949            }
2950            40..=44 if !anchors.is_empty() => {
2951                let multibuffer =
2952                    multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
2953                let prev_len = anchors.len();
2954                anchors = multibuffer
2955                    .refresh_anchors(&anchors)
2956                    .into_iter()
2957                    .map(|a| a.1)
2958                    .collect();
2959
2960                // Ensure the newly-refreshed anchors point to a valid excerpt and don't
2961                // overshoot its boundaries.
2962                assert_eq!(anchors.len(), prev_len);
2963                for anchor in &anchors {
2964                    if anchor.excerpt_id == ExcerptId::min()
2965                        || anchor.excerpt_id == ExcerptId::max()
2966                    {
2967                        continue;
2968                    }
2969
2970                    let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
2971                    assert_eq!(excerpt.id, anchor.excerpt_id);
2972                    assert!(excerpt.contains(anchor));
2973                }
2974            }
2975            45..=55 if !reference.excerpts.is_empty() => {
2976                multibuffer.update(cx, |multibuffer, cx| {
2977                    let snapshot = multibuffer.snapshot(cx);
2978                    let excerpt_ix = rng.random_range(0..reference.excerpts.len());
2979                    let excerpt = &reference.excerpts[excerpt_ix];
2980
2981                    // Skip inverted excerpts - hunks can't be collapsed
2982                    let buffer_id = excerpt.buffer.read(cx).remote_id();
2983                    if reference.inverted_diffs.contains_key(&buffer_id) {
2984                        return;
2985                    }
2986
2987                    let start = excerpt.range.start;
2988                    let end = excerpt.range.end;
2989                    let range = snapshot.anchor_in_excerpt(excerpt.id, start).unwrap()
2990                        ..snapshot.anchor_in_excerpt(excerpt.id, end).unwrap();
2991
2992                    log::info!(
2993                        "expanding diff hunks in range {:?} (excerpt id {:?}, index {excerpt_ix:?}, buffer id {:?})",
2994                        range.to_offset(&snapshot),
2995                        excerpt.id,
2996                        buffer_id,
2997                    );
2998                    reference.expand_diff_hunks(excerpt.id, start..end, cx);
2999                    multibuffer.expand_diff_hunks(vec![range], cx);
3000                });
3001            }
3002            56..=85 if needs_diff_calculation => {
3003                multibuffer.update(cx, |multibuffer, cx| {
3004                    for buffer in multibuffer.all_buffers() {
3005                        let snapshot = buffer.read(cx).snapshot();
3006                        let buffer_id = snapshot.remote_id();
3007
3008                        // Recalculate non-inverted diff if exists
3009                        if let Some(diff) = multibuffer.diff_for(buffer_id) {
3010                            diff.update(cx, |diff, cx| {
3011                                log::info!("recalculating diff for buffer {:?}", buffer_id,);
3012                                diff.recalculate_diff_sync(&snapshot.text, cx);
3013                            });
3014                        }
3015
3016                        // Recalculate inverted diff if this is a main buffer for one
3017                        if let Some(inverted_diff) = inverted_diff_main_buffers.get(&buffer_id) {
3018                            inverted_diff.update(cx, |diff, cx| {
3019                                log::info!(
3020                                    "recalculating inverted diff for main buffer {:?}",
3021                                    buffer_id,
3022                                );
3023                                diff.recalculate_diff_sync(&snapshot.text, cx);
3024                            });
3025                            // Update the stored snapshot in the reference model
3026                            reference.update_inverted_diff_snapshot(
3027                                inverted_diff,
3028                                snapshot.text.clone(),
3029                                cx,
3030                            );
3031                        }
3032                    }
3033                    reference.diffs_updated(cx);
3034                    needs_diff_calculation = false;
3035                });
3036            }
3037            _ => {
3038                // Decide if we're creating a new buffer or reusing an existing one
3039                let create_new_buffer = buffers.is_empty() || rng.random_bool(0.4);
3040                // Decide if this should be an inverted diff excerpt (only for new buffers, 30% chance)
3041                let create_inverted = create_new_buffer && rng.random_bool(0.3);
3042
3043                if create_inverted {
3044                    // Create a new main buffer
3045                    let mut main_buffer_text = util::RandomCharIter::new(&mut rng)
3046                        .take(256)
3047                        .collect::<String>();
3048                    let main_buffer = cx.new(|cx| Buffer::local(main_buffer_text.clone(), cx));
3049                    text::LineEnding::normalize(&mut main_buffer_text);
3050                    let main_buffer_id = main_buffer.read_with(cx, |buffer, _| buffer.remote_id());
3051                    base_texts.insert(main_buffer_id, main_buffer_text);
3052                    buffers.push(main_buffer.clone());
3053
3054                    // Generate different base text for the inverted diff
3055                    let inverted_base_text: String =
3056                        util::RandomCharIter::new(&mut rng).take(256).collect();
3057
3058                    let diff = cx.new(|cx| {
3059                        BufferDiff::new_with_base_text(
3060                            &inverted_base_text,
3061                            &main_buffer.read(cx).text_snapshot(),
3062                            cx,
3063                        )
3064                    });
3065
3066                    let base_text_buffer = diff.read_with(cx, |diff, _| diff.base_text_buffer());
3067
3068                    // Track for recalculation when main buffer is edited
3069                    inverted_diff_main_buffers.insert(main_buffer_id, diff.clone());
3070
3071                    let prev_excerpt_ix = rng.random_range(0..=reference.excerpts.len());
3072                    let prev_excerpt_id = reference
3073                        .excerpts
3074                        .get(prev_excerpt_ix)
3075                        .map_or(ExcerptId::max(), |e| e.id);
3076                    let excerpt_ix = (prev_excerpt_ix + 1).min(reference.excerpts.len());
3077
3078                    // Create excerpt from base_text_buffer
3079                    let (range, anchor_range) = base_text_buffer.read_with(cx, |buffer, _| {
3080                        let end_row = rng.random_range(0..=buffer.max_point().row);
3081                        let start_row = rng.random_range(0..=end_row);
3082                        let end_ix = buffer.point_to_offset(Point::new(end_row, 0));
3083                        let start_ix = buffer.point_to_offset(Point::new(start_row, 0));
3084                        let anchor_range =
3085                            buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
3086
3087                        log::info!(
3088                            "Inserting inverted excerpt at {} of {} for base_text_buffer {}: {:?}[{:?}] = {:?}",
3089                            excerpt_ix,
3090                            reference.excerpts.len(),
3091                            buffer.remote_id(),
3092                            buffer.text(),
3093                            start_ix..end_ix,
3094                            &buffer.text()[start_ix..end_ix]
3095                        );
3096
3097                        (start_ix..end_ix, anchor_range)
3098                    });
3099
3100                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
3101                        multibuffer
3102                            .insert_excerpts_after(
3103                                prev_excerpt_id,
3104                                base_text_buffer.clone(),
3105                                [ExcerptRange::new(range.clone())],
3106                                cx,
3107                            )
3108                            .pop()
3109                            .unwrap()
3110                    });
3111
3112                    reference.insert_excerpt_after(
3113                        prev_excerpt_id,
3114                        excerpt_id,
3115                        (base_text_buffer.clone(), anchor_range),
3116                    );
3117
3118                    let main_buffer_snapshot =
3119                        main_buffer.read_with(cx, |buf, _| buf.text_snapshot());
3120                    multibuffer.update(cx, |multibuffer, cx| {
3121                        multibuffer.add_inverted_diff(diff.clone(), main_buffer.clone(), cx);
3122                    });
3123                    cx.update(|cx| {
3124                        reference.add_inverted_diff(diff, main_buffer_snapshot, cx);
3125                    });
3126                } else {
3127                    // Non-inverted: existing logic
3128                    let buffer_handle = if create_new_buffer {
3129                        let mut base_text = util::RandomCharIter::new(&mut rng)
3130                            .take(256)
3131                            .collect::<String>();
3132
3133                        let buffer = cx.new(|cx| Buffer::local(base_text.clone(), cx));
3134                        text::LineEnding::normalize(&mut base_text);
3135                        base_texts.insert(
3136                            buffer.read_with(cx, |buffer, _| buffer.remote_id()),
3137                            base_text,
3138                        );
3139                        buffers.push(buffer);
3140                        buffers.last().unwrap()
3141                    } else {
3142                        buffers.choose(&mut rng).unwrap()
3143                    };
3144
3145                    let prev_excerpt_ix = rng.random_range(0..=reference.excerpts.len());
3146                    let prev_excerpt_id = reference
3147                        .excerpts
3148                        .get(prev_excerpt_ix)
3149                        .map_or(ExcerptId::max(), |e| e.id);
3150                    let excerpt_ix = (prev_excerpt_ix + 1).min(reference.excerpts.len());
3151
3152                    let (range, anchor_range) = buffer_handle.read_with(cx, |buffer, _| {
3153                        let end_row = rng.random_range(0..=buffer.max_point().row);
3154                        let start_row = rng.random_range(0..=end_row);
3155                        let end_ix = buffer.point_to_offset(Point::new(end_row, 0));
3156                        let start_ix = buffer.point_to_offset(Point::new(start_row, 0));
3157                        let anchor_range =
3158                            buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
3159
3160                        log::info!(
3161                            "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
3162                            excerpt_ix,
3163                            reference.excerpts.len(),
3164                            buffer.remote_id(),
3165                            buffer.text(),
3166                            start_ix..end_ix,
3167                            &buffer.text()[start_ix..end_ix]
3168                        );
3169
3170                        (start_ix..end_ix, anchor_range)
3171                    });
3172
3173                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
3174                        multibuffer
3175                            .insert_excerpts_after(
3176                                prev_excerpt_id,
3177                                buffer_handle.clone(),
3178                                [ExcerptRange::new(range.clone())],
3179                                cx,
3180                            )
3181                            .pop()
3182                            .unwrap()
3183                    });
3184
3185                    reference.insert_excerpt_after(
3186                        prev_excerpt_id,
3187                        excerpt_id,
3188                        (buffer_handle.clone(), anchor_range),
3189                    );
3190
3191                    multibuffer.update(cx, |multibuffer, cx| {
3192                        let id = buffer_handle.read(cx).remote_id();
3193                        if multibuffer.diff_for(id).is_none() {
3194                            let base_text = base_texts.get(&id).unwrap();
3195                            let diff = cx.new(|cx| {
3196                                BufferDiff::new_with_base_text(
3197                                    base_text,
3198                                    &buffer_handle.read(cx).text_snapshot(),
3199                                    cx,
3200                                )
3201                            });
3202                            reference.add_diff(diff.clone(), cx);
3203                            multibuffer.add_diff(diff, cx)
3204                        }
3205                    });
3206                }
3207            }
3208        }
3209
3210        if rng.random_bool(0.3) {
3211            multibuffer.update(cx, |multibuffer, cx| {
3212                old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
3213            })
3214        }
3215
3216        multibuffer.read_with(cx, |multibuffer, cx| {
3217            check_multibuffer(multibuffer, &reference, &anchors, cx, &mut rng);
3218        });
3219    }
3220    let snapshot = multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
3221    for (old_snapshot, subscription) in old_versions {
3222        check_multibuffer_edits(&snapshot, &old_snapshot, subscription);
3223    }
3224}
3225
3226fn check_multibuffer(
3227    multibuffer: &MultiBuffer,
3228    reference: &ReferenceMultibuffer,
3229    anchors: &[Anchor],
3230    cx: &App,
3231    rng: &mut StdRng,
3232) {
3233    let snapshot = multibuffer.snapshot(cx);
3234    let actual_text = snapshot.text();
3235    let actual_boundary_rows = snapshot
3236        .excerpt_boundaries_in_range(MultiBufferOffset(0)..)
3237        .map(|b| b.row)
3238        .collect::<HashSet<_>>();
3239    let actual_row_infos = snapshot.row_infos(MultiBufferRow(0)).collect::<Vec<_>>();
3240
3241    let (expected_text, expected_row_infos, expected_boundary_rows) =
3242        reference.expected_content(cx);
3243
3244    let has_diff = actual_row_infos
3245        .iter()
3246        .any(|info| info.diff_status.is_some())
3247        || expected_row_infos
3248            .iter()
3249            .any(|info| info.diff_status.is_some());
3250    let actual_diff = format_diff(
3251        &actual_text,
3252        &actual_row_infos,
3253        &actual_boundary_rows,
3254        Some(has_diff),
3255    );
3256    let expected_diff = format_diff(
3257        &expected_text,
3258        &expected_row_infos,
3259        &expected_boundary_rows,
3260        Some(has_diff),
3261    );
3262
3263    log::info!("Multibuffer content:\n{}", actual_diff);
3264
3265    assert_eq!(
3266        actual_row_infos.len(),
3267        actual_text.split('\n').count(),
3268        "line count: {}",
3269        actual_text.split('\n').count()
3270    );
3271    pretty_assertions::assert_eq!(actual_diff, expected_diff);
3272    pretty_assertions::assert_eq!(actual_text, expected_text);
3273    pretty_assertions::assert_eq!(actual_row_infos, expected_row_infos);
3274
3275    for _ in 0..5 {
3276        let start_row = rng.random_range(0..=expected_row_infos.len());
3277        assert_eq!(
3278            snapshot
3279                .row_infos(MultiBufferRow(start_row as u32))
3280                .collect::<Vec<_>>(),
3281            &expected_row_infos[start_row..],
3282            "buffer_rows({})",
3283            start_row
3284        );
3285    }
3286
3287    assert_eq!(
3288        snapshot.widest_line_number(),
3289        expected_row_infos
3290            .into_iter()
3291            .filter_map(|info| {
3292                // For inverted diffs, deleted rows are visible and should be counted.
3293                // Only filter out deleted rows that are NOT from inverted diffs.
3294                let is_inverted_diff = info
3295                    .buffer_id
3296                    .is_some_and(|id| reference.inverted_diffs.contains_key(&id));
3297                if info.diff_status.is_some_and(|status| status.is_deleted()) && !is_inverted_diff {
3298                    None
3299                } else {
3300                    info.buffer_row
3301                }
3302            })
3303            .max()
3304            .unwrap()
3305            + 1
3306    );
3307    let reference_ranges = reference
3308        .excerpts
3309        .iter()
3310        .map(|excerpt| {
3311            (
3312                excerpt.id,
3313                excerpt.range.to_offset(&excerpt.buffer.read(cx).snapshot()),
3314            )
3315        })
3316        .collect::<HashMap<_, _>>();
3317    for i in 0..snapshot.len().0 {
3318        let excerpt = snapshot
3319            .excerpt_containing(MultiBufferOffset(i)..MultiBufferOffset(i))
3320            .unwrap();
3321        assert_eq!(
3322            excerpt.buffer_range().start.0..excerpt.buffer_range().end.0,
3323            reference_ranges[&excerpt.id()]
3324        );
3325    }
3326
3327    assert_consistent_line_numbers(&snapshot);
3328    assert_position_translation(&snapshot);
3329
3330    for (row, line) in expected_text.split('\n').enumerate() {
3331        assert_eq!(
3332            snapshot.line_len(MultiBufferRow(row as u32)),
3333            line.len() as u32,
3334            "line_len({}).",
3335            row
3336        );
3337    }
3338
3339    let text_rope = Rope::from(expected_text.as_str());
3340    for _ in 0..10 {
3341        let end_ix = text_rope.clip_offset(rng.random_range(0..=text_rope.len()), Bias::Right);
3342        let start_ix = text_rope.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3343
3344        let text_for_range = snapshot
3345            .text_for_range(MultiBufferOffset(start_ix)..MultiBufferOffset(end_ix))
3346            .collect::<String>();
3347        assert_eq!(
3348            text_for_range,
3349            &expected_text[start_ix..end_ix],
3350            "incorrect text for range {:?}",
3351            start_ix..end_ix
3352        );
3353
3354        let expected_summary =
3355            MBTextSummary::from(TextSummary::from(&expected_text[start_ix..end_ix]));
3356        assert_eq!(
3357            snapshot.text_summary_for_range::<MBTextSummary, _>(
3358                MultiBufferOffset(start_ix)..MultiBufferOffset(end_ix)
3359            ),
3360            expected_summary,
3361            "incorrect summary for range {:?}",
3362            start_ix..end_ix
3363        );
3364    }
3365
3366    // Anchor resolution
3367    let summaries = snapshot.summaries_for_anchors::<MultiBufferOffset, _>(anchors);
3368    assert_eq!(anchors.len(), summaries.len());
3369    for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
3370        assert!(resolved_offset <= snapshot.len());
3371        assert_eq!(
3372            snapshot.summary_for_anchor::<MultiBufferOffset>(anchor),
3373            resolved_offset,
3374            "anchor: {:?}",
3375            anchor
3376        );
3377    }
3378
3379    for _ in 0..10 {
3380        let end_ix = text_rope.clip_offset(rng.random_range(0..=text_rope.len()), Bias::Right);
3381        assert_eq!(
3382            snapshot
3383                .reversed_chars_at(MultiBufferOffset(end_ix))
3384                .collect::<String>(),
3385            expected_text[..end_ix].chars().rev().collect::<String>(),
3386        );
3387    }
3388
3389    for _ in 0..10 {
3390        let end_ix = rng.random_range(0..=text_rope.len());
3391        let end_ix = text_rope.floor_char_boundary(end_ix);
3392        let start_ix = rng.random_range(0..=end_ix);
3393        let start_ix = text_rope.floor_char_boundary(start_ix);
3394        assert_eq!(
3395            snapshot
3396                .bytes_in_range(MultiBufferOffset(start_ix)..MultiBufferOffset(end_ix))
3397                .flatten()
3398                .copied()
3399                .collect::<Vec<_>>(),
3400            expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3401            "bytes_in_range({:?})",
3402            start_ix..end_ix,
3403        );
3404    }
3405}
3406
3407fn check_multibuffer_edits(
3408    snapshot: &MultiBufferSnapshot,
3409    old_snapshot: &MultiBufferSnapshot,
3410    subscription: Subscription<MultiBufferOffset>,
3411) {
3412    let edits = subscription.consume().into_inner();
3413
3414    log::info!(
3415        "applying subscription edits to old text: {:?}: {:#?}",
3416        old_snapshot.text(),
3417        edits,
3418    );
3419
3420    let mut text = old_snapshot.text();
3421    for edit in edits {
3422        let new_text: String = snapshot
3423            .text_for_range(edit.new.start..edit.new.end)
3424            .collect();
3425        text.replace_range(
3426            (edit.new.start.0..edit.new.start.0 + (edit.old.end.0 - edit.old.start.0)).clone(),
3427            &new_text,
3428        );
3429        pretty_assertions::assert_eq!(
3430            &text[0..edit.new.end.0],
3431            snapshot
3432                .text_for_range(MultiBufferOffset(0)..edit.new.end)
3433                .collect::<String>()
3434        );
3435    }
3436    pretty_assertions::assert_eq!(text, snapshot.text());
3437}
3438
3439#[gpui::test]
3440fn test_history(cx: &mut App) {
3441    let test_settings = SettingsStore::test(cx);
3442    cx.set_global(test_settings);
3443
3444    let group_interval: Duration = Duration::from_millis(1);
3445    let buffer_1 = cx.new(|cx| {
3446        let mut buf = Buffer::local("1234", cx);
3447        buf.set_group_interval(group_interval);
3448        buf
3449    });
3450    let buffer_2 = cx.new(|cx| {
3451        let mut buf = Buffer::local("5678", cx);
3452        buf.set_group_interval(group_interval);
3453        buf
3454    });
3455    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
3456    multibuffer.update(cx, |this, _| {
3457        this.set_group_interval(group_interval);
3458    });
3459    multibuffer.update(cx, |multibuffer, cx| {
3460        multibuffer.push_excerpts(
3461            buffer_1.clone(),
3462            [ExcerptRange::new(0..buffer_1.read(cx).len())],
3463            cx,
3464        );
3465        multibuffer.push_excerpts(
3466            buffer_2.clone(),
3467            [ExcerptRange::new(0..buffer_2.read(cx).len())],
3468            cx,
3469        );
3470    });
3471
3472    let mut now = Instant::now();
3473
3474    multibuffer.update(cx, |multibuffer, cx| {
3475        let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
3476        multibuffer.edit(
3477            [
3478                (Point::new(0, 0)..Point::new(0, 0), "A"),
3479                (Point::new(1, 0)..Point::new(1, 0), "A"),
3480            ],
3481            None,
3482            cx,
3483        );
3484        multibuffer.edit(
3485            [
3486                (Point::new(0, 1)..Point::new(0, 1), "B"),
3487                (Point::new(1, 1)..Point::new(1, 1), "B"),
3488            ],
3489            None,
3490            cx,
3491        );
3492        multibuffer.end_transaction_at(now, cx);
3493        assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3494
3495        // Verify edited ranges for transaction 1
3496        assert_eq!(
3497            multibuffer.edited_ranges_for_transaction(transaction_1, cx),
3498            &[
3499                Point::new(0, 0)..Point::new(0, 2),
3500                Point::new(1, 0)..Point::new(1, 2)
3501            ]
3502        );
3503
3504        // Edit buffer 1 through the multibuffer
3505        now += 2 * group_interval;
3506        multibuffer.start_transaction_at(now, cx);
3507        multibuffer.edit(
3508            [(MultiBufferOffset(2)..MultiBufferOffset(2), "C")],
3509            None,
3510            cx,
3511        );
3512        multibuffer.end_transaction_at(now, cx);
3513        assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3514
3515        // Edit buffer 1 independently
3516        buffer_1.update(cx, |buffer_1, cx| {
3517            buffer_1.start_transaction_at(now);
3518            buffer_1.edit([(3..3, "D")], None, cx);
3519            buffer_1.end_transaction_at(now, cx);
3520
3521            now += 2 * group_interval;
3522            buffer_1.start_transaction_at(now);
3523            buffer_1.edit([(4..4, "E")], None, cx);
3524            buffer_1.end_transaction_at(now, cx);
3525        });
3526        assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
3527
3528        // An undo in the multibuffer undoes the multibuffer transaction
3529        // and also any individual buffer edits that have occurred since
3530        // that transaction.
3531        multibuffer.undo(cx);
3532        assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3533
3534        multibuffer.undo(cx);
3535        assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3536
3537        multibuffer.redo(cx);
3538        assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3539
3540        multibuffer.redo(cx);
3541        assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
3542
3543        // Undo buffer 2 independently.
3544        buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
3545        assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
3546
3547        // An undo in the multibuffer undoes the components of the
3548        // the last multibuffer transaction that are not already undone.
3549        multibuffer.undo(cx);
3550        assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
3551
3552        multibuffer.undo(cx);
3553        assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3554
3555        multibuffer.redo(cx);
3556        assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3557
3558        buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3559        assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
3560
3561        // Redo stack gets cleared after an edit.
3562        now += 2 * group_interval;
3563        multibuffer.start_transaction_at(now, cx);
3564        multibuffer.edit(
3565            [(MultiBufferOffset(0)..MultiBufferOffset(0), "X")],
3566            None,
3567            cx,
3568        );
3569        multibuffer.end_transaction_at(now, cx);
3570        assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
3571        multibuffer.redo(cx);
3572        assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
3573        multibuffer.undo(cx);
3574        assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
3575        multibuffer.undo(cx);
3576        assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3577
3578        // Transactions can be grouped manually.
3579        multibuffer.redo(cx);
3580        multibuffer.redo(cx);
3581        assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
3582        multibuffer.group_until_transaction(transaction_1, cx);
3583        multibuffer.undo(cx);
3584        assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3585        multibuffer.redo(cx);
3586        assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
3587    });
3588}
3589
3590#[gpui::test]
3591async fn test_enclosing_indent(cx: &mut TestAppContext) {
3592    async fn enclosing_indent(
3593        text: &str,
3594        buffer_row: u32,
3595        cx: &mut TestAppContext,
3596    ) -> Option<(Range<u32>, LineIndent)> {
3597        let buffer = cx.update(|cx| MultiBuffer::build_simple(text, cx));
3598        let snapshot = cx.read(|cx| buffer.read(cx).snapshot(cx));
3599        let (range, indent) = snapshot
3600            .enclosing_indent(MultiBufferRow(buffer_row))
3601            .await?;
3602        Some((range.start.0..range.end.0, indent))
3603    }
3604
3605    assert_eq!(
3606        enclosing_indent(
3607            indoc!(
3608                "
3609                fn b() {
3610                    if c {
3611                        let d = 2;
3612                    }
3613                }
3614                "
3615            ),
3616            1,
3617            cx,
3618        )
3619        .await,
3620        Some((
3621            1..2,
3622            LineIndent {
3623                tabs: 0,
3624                spaces: 4,
3625                line_blank: false,
3626            }
3627        ))
3628    );
3629
3630    assert_eq!(
3631        enclosing_indent(
3632            indoc!(
3633                "
3634                fn b() {
3635                    if c {
3636                        let d = 2;
3637                    }
3638                }
3639                "
3640            ),
3641            2,
3642            cx,
3643        )
3644        .await,
3645        Some((
3646            1..2,
3647            LineIndent {
3648                tabs: 0,
3649                spaces: 4,
3650                line_blank: false,
3651            }
3652        ))
3653    );
3654
3655    assert_eq!(
3656        enclosing_indent(
3657            indoc!(
3658                "
3659                fn b() {
3660                    if c {
3661                        let d = 2;
3662
3663                        let e = 5;
3664                    }
3665                }
3666                "
3667            ),
3668            3,
3669            cx,
3670        )
3671        .await,
3672        Some((
3673            1..4,
3674            LineIndent {
3675                tabs: 0,
3676                spaces: 4,
3677                line_blank: false,
3678            }
3679        ))
3680    );
3681}
3682
3683#[gpui::test]
3684async fn test_summaries_for_anchors(cx: &mut TestAppContext) {
3685    let base_text_1 = indoc!(
3686        "
3687        bar
3688        "
3689    );
3690    let text_1 = indoc!(
3691        "
3692        BAR
3693        "
3694    );
3695    let base_text_2 = indoc!(
3696        "
3697        foo
3698        "
3699    );
3700    let text_2 = indoc!(
3701        "
3702        FOO
3703        "
3704    );
3705
3706    let buffer_1 = cx.new(|cx| Buffer::local(text_1, cx));
3707    let buffer_2 = cx.new(|cx| Buffer::local(text_2, cx));
3708    let diff_1 = cx.new(|cx| {
3709        BufferDiff::new_with_base_text(base_text_1, &buffer_1.read(cx).text_snapshot(), cx)
3710    });
3711    let diff_2 = cx.new(|cx| {
3712        BufferDiff::new_with_base_text(base_text_2, &buffer_2.read(cx).text_snapshot(), cx)
3713    });
3714    cx.run_until_parked();
3715
3716    let mut ids = vec![];
3717    let multibuffer = cx.new(|cx| {
3718        let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3719        multibuffer.set_all_diff_hunks_expanded(cx);
3720        ids.extend(multibuffer.push_excerpts(
3721            buffer_1.clone(),
3722            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
3723            cx,
3724        ));
3725        ids.extend(multibuffer.push_excerpts(
3726            buffer_2.clone(),
3727            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
3728            cx,
3729        ));
3730        multibuffer.add_diff(diff_1.clone(), cx);
3731        multibuffer.add_diff(diff_2.clone(), cx);
3732        multibuffer
3733    });
3734
3735    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
3736        (multibuffer.snapshot(cx), multibuffer.subscribe())
3737    });
3738
3739    assert_new_snapshot(
3740        &multibuffer,
3741        &mut snapshot,
3742        &mut subscription,
3743        cx,
3744        indoc!(
3745            "
3746            - bar
3747            + BAR
3748
3749            - foo
3750            + FOO
3751            "
3752        ),
3753    );
3754
3755    let anchor_1 = Anchor::in_buffer(ids[0], text::Anchor::MIN);
3756    let point_1 = snapshot.summaries_for_anchors::<Point, _>([&anchor_1])[0];
3757    assert_eq!(point_1, Point::new(0, 0));
3758
3759    let anchor_2 = Anchor::in_buffer(ids[1], text::Anchor::MIN);
3760    let point_2 = snapshot.summaries_for_anchors::<Point, _>([&anchor_2])[0];
3761    assert_eq!(point_2, Point::new(3, 0));
3762}
3763
3764#[gpui::test]
3765async fn test_trailing_deletion_without_newline(cx: &mut TestAppContext) {
3766    let base_text_1 = "one\ntwo".to_owned();
3767    let text_1 = "one\n".to_owned();
3768
3769    let buffer_1 = cx.new(|cx| Buffer::local(text_1, cx));
3770    let diff_1 = cx.new(|cx| {
3771        BufferDiff::new_with_base_text(&base_text_1, &buffer_1.read(cx).text_snapshot(), cx)
3772    });
3773    cx.run_until_parked();
3774
3775    let multibuffer = cx.new(|cx| {
3776        let mut multibuffer = MultiBuffer::singleton(buffer_1.clone(), cx);
3777        multibuffer.add_diff(diff_1.clone(), cx);
3778        multibuffer.expand_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
3779        multibuffer
3780    });
3781
3782    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
3783        (multibuffer.snapshot(cx), multibuffer.subscribe())
3784    });
3785
3786    assert_new_snapshot(
3787        &multibuffer,
3788        &mut snapshot,
3789        &mut subscription,
3790        cx,
3791        indoc!(
3792            "
3793              one
3794            - two
3795            "
3796        ),
3797    );
3798
3799    assert_eq!(snapshot.max_point(), Point::new(2, 0));
3800    assert_eq!(snapshot.len().0, 8);
3801
3802    assert_eq!(
3803        snapshot
3804            .dimensions_from_points::<Point>([Point::new(2, 0)])
3805            .collect::<Vec<_>>(),
3806        vec![Point::new(2, 0)]
3807    );
3808
3809    let (_, translated_offset) = snapshot.point_to_buffer_offset(Point::new(2, 0)).unwrap();
3810    assert_eq!(translated_offset.0, "one\n".len());
3811    let (_, translated_point, _) = snapshot.point_to_buffer_point(Point::new(2, 0)).unwrap();
3812    assert_eq!(translated_point, Point::new(1, 0));
3813
3814    // The same, for an excerpt that's not at the end of the multibuffer.
3815
3816    let text_2 = "foo\n".to_owned();
3817    let buffer_2 = cx.new(|cx| Buffer::local(&text_2, cx));
3818    multibuffer.update(cx, |multibuffer, cx| {
3819        multibuffer.push_excerpts(
3820            buffer_2.clone(),
3821            [ExcerptRange::new(Point::new(0, 0)..Point::new(1, 0))],
3822            cx,
3823        );
3824    });
3825
3826    assert_new_snapshot(
3827        &multibuffer,
3828        &mut snapshot,
3829        &mut subscription,
3830        cx,
3831        indoc!(
3832            "
3833              one
3834            - two
3835
3836              foo
3837            "
3838        ),
3839    );
3840
3841    assert_eq!(
3842        snapshot
3843            .dimensions_from_points::<Point>([Point::new(2, 0)])
3844            .collect::<Vec<_>>(),
3845        vec![Point::new(2, 0)]
3846    );
3847
3848    let buffer_1_id = buffer_1.read_with(cx, |buffer_1, _| buffer_1.remote_id());
3849    let (buffer, translated_offset) = snapshot.point_to_buffer_offset(Point::new(2, 0)).unwrap();
3850    assert_eq!(buffer.remote_id(), buffer_1_id);
3851    assert_eq!(translated_offset.0, "one\n".len());
3852    let (buffer, translated_point, _) = snapshot.point_to_buffer_point(Point::new(2, 0)).unwrap();
3853    assert_eq!(buffer.remote_id(), buffer_1_id);
3854    assert_eq!(translated_point, Point::new(1, 0));
3855}
3856
3857fn format_diff(
3858    text: &str,
3859    row_infos: &Vec<RowInfo>,
3860    boundary_rows: &HashSet<MultiBufferRow>,
3861    has_diff: Option<bool>,
3862) -> String {
3863    let has_diff =
3864        has_diff.unwrap_or_else(|| row_infos.iter().any(|info| info.diff_status.is_some()));
3865    text.split('\n')
3866        .enumerate()
3867        .zip(row_infos)
3868        .map(|((ix, line), info)| {
3869            let marker = match info.diff_status.map(|status| status.kind) {
3870                Some(DiffHunkStatusKind::Added) => "+ ",
3871                Some(DiffHunkStatusKind::Deleted) => "- ",
3872                Some(DiffHunkStatusKind::Modified) => unreachable!(),
3873                None => {
3874                    if has_diff && !line.is_empty() {
3875                        "  "
3876                    } else {
3877                        ""
3878                    }
3879                }
3880            };
3881            let boundary_row = if boundary_rows.contains(&MultiBufferRow(ix as u32)) {
3882                if has_diff {
3883                    "  ----------\n"
3884                } else {
3885                    "---------\n"
3886                }
3887            } else {
3888                ""
3889            };
3890            let expand = info
3891                .expand_info
3892                .map(|expand_info| match expand_info.direction {
3893                    ExpandExcerptDirection::Up => " [↑]",
3894                    ExpandExcerptDirection::Down => " [↓]",
3895                    ExpandExcerptDirection::UpAndDown => " [↕]",
3896                })
3897                .unwrap_or_default();
3898
3899            format!("{boundary_row}{marker}{line}{expand}")
3900            // let mbr = info
3901            //     .multibuffer_row
3902            //     .map(|row| format!("{:0>3}", row.0))
3903            //     .unwrap_or_else(|| "???".to_string());
3904            // let byte_range = format!("{byte_range_start:0>3}..{byte_range_end:0>3}");
3905            // format!("{boundary_row}Row: {mbr}, Bytes: {byte_range} | {marker}{line}{expand}")
3906        })
3907        .collect::<Vec<_>>()
3908        .join("\n")
3909}
3910
3911// fn format_transforms(snapshot: &MultiBufferSnapshot) -> String {
3912//     snapshot
3913//         .diff_transforms
3914//         .iter()
3915//         .map(|transform| {
3916//             let (kind, summary) = match transform {
3917//                 DiffTransform::DeletedHunk { summary, .. } => ("   Deleted", (*summary).into()),
3918//                 DiffTransform::FilteredInsertedHunk { summary, .. } => ("  Filtered", *summary),
3919//                 DiffTransform::InsertedHunk { summary, .. } => ("  Inserted", *summary),
3920//                 DiffTransform::Unmodified { summary, .. } => ("Unmodified", *summary),
3921//             };
3922//             format!("{kind}(len: {}, lines: {:?})", summary.len, summary.lines)
3923//         })
3924//         .join("\n")
3925// }
3926
3927// fn format_excerpts(snapshot: &MultiBufferSnapshot) -> String {
3928//     snapshot
3929//         .excerpts
3930//         .iter()
3931//         .map(|excerpt| {
3932//             format!(
3933//                 "Excerpt(buffer_range = {:?}, lines = {:?}, has_trailing_newline = {:?})",
3934//                 excerpt.range.context.to_point(&excerpt.buffer),
3935//                 excerpt.text_summary.lines,
3936//                 excerpt.has_trailing_newline
3937//             )
3938//         })
3939//         .join("\n")
3940// }
3941
3942#[gpui::test]
3943async fn test_singleton_with_inverted_diff(cx: &mut TestAppContext) {
3944    let text = indoc!(
3945        "
3946        ZERO
3947        one
3948        TWO
3949        three
3950        six
3951        "
3952    );
3953    let base_text = indoc!(
3954        "
3955        one
3956        two
3957        three
3958        four
3959        five
3960        six
3961        "
3962    );
3963
3964    let buffer = cx.new(|cx| Buffer::local(text, cx));
3965    let diff = cx
3966        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
3967    cx.run_until_parked();
3968
3969    let base_text_buffer = diff.read_with(cx, |diff, _| diff.base_text_buffer());
3970
3971    let multibuffer = cx.new(|cx| {
3972        let mut multibuffer = MultiBuffer::singleton(base_text_buffer.clone(), cx);
3973        multibuffer.set_all_diff_hunks_expanded(cx);
3974        multibuffer.add_inverted_diff(diff.clone(), buffer.clone(), cx);
3975        multibuffer
3976    });
3977
3978    let (mut snapshot, mut subscription) = multibuffer.update(cx, |multibuffer, cx| {
3979        (multibuffer.snapshot(cx), multibuffer.subscribe())
3980    });
3981
3982    assert_eq!(snapshot.text(), base_text);
3983    assert_new_snapshot(
3984        &multibuffer,
3985        &mut snapshot,
3986        &mut subscription,
3987        cx,
3988        indoc!(
3989            "
3990              one
3991            - two
3992              three
3993            - four
3994            - five
3995              six
3996            "
3997        ),
3998    );
3999
4000    buffer.update(cx, |buffer, cx| {
4001        buffer.edit_via_marked_text(
4002            indoc!(
4003                "
4004                ZERO
4005                one
4006                «<inserted>»W«O
4007                T»hree
4008                six
4009                "
4010            ),
4011            None,
4012            cx,
4013        );
4014    });
4015    cx.run_until_parked();
4016    let update = diff
4017        .update(cx, |diff, cx| {
4018            diff.update_diff(
4019                buffer.read(cx).text_snapshot(),
4020                Some(base_text.into()),
4021                false,
4022                None,
4023                cx,
4024            )
4025        })
4026        .await;
4027    diff.update(cx, |diff, cx| {
4028        diff.set_snapshot(update, &buffer.read(cx).text_snapshot(), cx);
4029    });
4030    cx.run_until_parked();
4031
4032    assert_new_snapshot(
4033        &multibuffer,
4034        &mut snapshot,
4035        &mut subscription,
4036        cx,
4037        indoc! {
4038            "
4039              one
4040            - two
4041            - three
4042            - four
4043            - five
4044              six
4045            "
4046        },
4047    );
4048
4049    buffer.update(cx, |buffer, cx| {
4050        buffer.set_text("ZERO\nONE\nTWO\n", cx);
4051    });
4052    cx.run_until_parked();
4053    let update = diff
4054        .update(cx, |diff, cx| {
4055            diff.update_diff(
4056                buffer.read(cx).text_snapshot(),
4057                Some(base_text.into()),
4058                false,
4059                None,
4060                cx,
4061            )
4062        })
4063        .await;
4064    diff.update(cx, |diff, cx| {
4065        diff.set_snapshot(update, &buffer.read(cx).text_snapshot(), cx);
4066    });
4067    cx.run_until_parked();
4068
4069    assert_new_snapshot(
4070        &multibuffer,
4071        &mut snapshot,
4072        &mut subscription,
4073        cx,
4074        indoc! {
4075            "
4076            - one
4077            - two
4078            - three
4079            - four
4080            - five
4081            - six
4082            "
4083        },
4084    );
4085
4086    diff.update(cx, |diff, cx| {
4087        diff.set_base_text(
4088            Some("new base\n".into()),
4089            None,
4090            buffer.read(cx).text_snapshot(),
4091            cx,
4092        )
4093    })
4094    .await
4095    .unwrap();
4096    cx.run_until_parked();
4097
4098    assert_new_snapshot(
4099        &multibuffer,
4100        &mut snapshot,
4101        &mut subscription,
4102        cx,
4103        indoc! {"
4104            - new base
4105        "},
4106    );
4107}
4108
4109#[track_caller]
4110fn assert_excerpts_match(
4111    multibuffer: &Entity<MultiBuffer>,
4112    cx: &mut TestAppContext,
4113    expected: &str,
4114) {
4115    let mut output = String::new();
4116    multibuffer.read_with(cx, |multibuffer, cx| {
4117        for (_, buffer, range) in multibuffer.snapshot(cx).excerpts() {
4118            output.push_str("-----\n");
4119            output.extend(buffer.text_for_range(range.context));
4120            if !output.ends_with('\n') {
4121                output.push('\n');
4122            }
4123        }
4124    });
4125    assert_eq!(output, expected);
4126}
4127
4128#[track_caller]
4129fn assert_new_snapshot(
4130    multibuffer: &Entity<MultiBuffer>,
4131    snapshot: &mut MultiBufferSnapshot,
4132    subscription: &mut Subscription<MultiBufferOffset>,
4133    cx: &mut TestAppContext,
4134    expected_diff: &str,
4135) {
4136    let new_snapshot = multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
4137    let actual_text = new_snapshot.text();
4138    let line_infos = new_snapshot
4139        .row_infos(MultiBufferRow(0))
4140        .collect::<Vec<_>>();
4141    let actual_diff = format_diff(&actual_text, &line_infos, &Default::default(), None);
4142    pretty_assertions::assert_eq!(actual_diff, expected_diff);
4143    check_edits(
4144        snapshot,
4145        &new_snapshot,
4146        &subscription.consume().into_inner(),
4147    );
4148    *snapshot = new_snapshot;
4149}
4150
4151#[track_caller]
4152fn check_edits(
4153    old_snapshot: &MultiBufferSnapshot,
4154    new_snapshot: &MultiBufferSnapshot,
4155    edits: &[Edit<MultiBufferOffset>],
4156) {
4157    let mut text = old_snapshot.text();
4158    let new_text = new_snapshot.text();
4159    for edit in edits.iter().rev() {
4160        if !text.is_char_boundary(edit.old.start.0)
4161            || !text.is_char_boundary(edit.old.end.0)
4162            || !new_text.is_char_boundary(edit.new.start.0)
4163            || !new_text.is_char_boundary(edit.new.end.0)
4164        {
4165            panic!(
4166                "invalid edits: {:?}\nold text: {:?}\nnew text: {:?}",
4167                edits, text, new_text
4168            );
4169        }
4170
4171        text.replace_range(
4172            edit.old.start.0..edit.old.end.0,
4173            &new_text[edit.new.start.0..edit.new.end.0],
4174        );
4175    }
4176
4177    pretty_assertions::assert_eq!(text, new_text, "invalid edits: {:?}", edits);
4178}
4179
4180#[track_caller]
4181fn assert_chunks_in_ranges(snapshot: &MultiBufferSnapshot) {
4182    let full_text = snapshot.text();
4183    for ix in 0..full_text.len() {
4184        let mut chunks = snapshot.chunks(MultiBufferOffset(0)..snapshot.len(), false);
4185        chunks.seek(MultiBufferOffset(ix)..snapshot.len());
4186        let tail = chunks.map(|chunk| chunk.text).collect::<String>();
4187        assert_eq!(tail, &full_text[ix..], "seek to range: {:?}", ix..);
4188    }
4189}
4190
4191#[track_caller]
4192fn assert_consistent_line_numbers(snapshot: &MultiBufferSnapshot) {
4193    let all_line_numbers = snapshot.row_infos(MultiBufferRow(0)).collect::<Vec<_>>();
4194    for start_row in 1..all_line_numbers.len() {
4195        let line_numbers = snapshot
4196            .row_infos(MultiBufferRow(start_row as u32))
4197            .collect::<Vec<_>>();
4198        assert_eq!(
4199            line_numbers,
4200            all_line_numbers[start_row..],
4201            "start_row: {start_row}"
4202        );
4203    }
4204}
4205
4206#[track_caller]
4207fn assert_position_translation(snapshot: &MultiBufferSnapshot) {
4208    let text = Rope::from(snapshot.text());
4209
4210    let mut left_anchors = Vec::new();
4211    let mut right_anchors = Vec::new();
4212    let mut offsets = Vec::new();
4213    let mut points = Vec::new();
4214    for offset in 0..=text.len() + 1 {
4215        let offset = MultiBufferOffset(offset);
4216        let clipped_left = snapshot.clip_offset(offset, Bias::Left);
4217        let clipped_right = snapshot.clip_offset(offset, Bias::Right);
4218        assert_eq!(
4219            clipped_left.0,
4220            text.clip_offset(offset.0, Bias::Left),
4221            "clip_offset({offset:?}, Left)"
4222        );
4223        assert_eq!(
4224            clipped_right.0,
4225            text.clip_offset(offset.0, Bias::Right),
4226            "clip_offset({offset:?}, Right)"
4227        );
4228        assert_eq!(
4229            snapshot.offset_to_point(clipped_left),
4230            text.offset_to_point(clipped_left.0),
4231            "offset_to_point({})",
4232            clipped_left.0
4233        );
4234        assert_eq!(
4235            snapshot.offset_to_point(clipped_right),
4236            text.offset_to_point(clipped_right.0),
4237            "offset_to_point({})",
4238            clipped_right.0
4239        );
4240        let anchor_after = snapshot.anchor_after(clipped_left);
4241        assert_eq!(
4242            anchor_after.to_offset(snapshot),
4243            clipped_left,
4244            "anchor_after({}).to_offset {anchor_after:?}",
4245            clipped_left.0
4246        );
4247        let anchor_before = snapshot.anchor_before(clipped_left);
4248        assert_eq!(
4249            anchor_before.to_offset(snapshot),
4250            clipped_left,
4251            "anchor_before({}).to_offset",
4252            clipped_left.0
4253        );
4254        left_anchors.push(anchor_before);
4255        right_anchors.push(anchor_after);
4256        offsets.push(clipped_left);
4257        points.push(text.offset_to_point(clipped_left.0));
4258    }
4259
4260    for row in 0..text.max_point().row {
4261        for column in 0..text.line_len(row) + 1 {
4262            let point = Point { row, column };
4263            let clipped_left = snapshot.clip_point(point, Bias::Left);
4264            let clipped_right = snapshot.clip_point(point, Bias::Right);
4265            assert_eq!(
4266                clipped_left,
4267                text.clip_point(point, Bias::Left),
4268                "clip_point({point:?}, Left)"
4269            );
4270            assert_eq!(
4271                clipped_right,
4272                text.clip_point(point, Bias::Right),
4273                "clip_point({point:?}, Right)"
4274            );
4275            assert_eq!(
4276                snapshot.point_to_offset(clipped_left).0,
4277                text.point_to_offset(clipped_left),
4278                "point_to_offset({clipped_left:?})"
4279            );
4280            assert_eq!(
4281                snapshot.point_to_offset(clipped_right).0,
4282                text.point_to_offset(clipped_right),
4283                "point_to_offset({clipped_right:?})"
4284            );
4285        }
4286    }
4287
4288    assert_eq!(
4289        snapshot.summaries_for_anchors::<MultiBufferOffset, _>(&left_anchors),
4290        offsets,
4291        "left_anchors <-> offsets"
4292    );
4293    assert_eq!(
4294        snapshot.summaries_for_anchors::<Point, _>(&left_anchors),
4295        points,
4296        "left_anchors <-> points"
4297    );
4298    assert_eq!(
4299        snapshot.summaries_for_anchors::<MultiBufferOffset, _>(&right_anchors),
4300        offsets,
4301        "right_anchors <-> offsets"
4302    );
4303    assert_eq!(
4304        snapshot.summaries_for_anchors::<Point, _>(&right_anchors),
4305        points,
4306        "right_anchors <-> points"
4307    );
4308
4309    for (anchors, bias) in [(&left_anchors, Bias::Left), (&right_anchors, Bias::Right)] {
4310        for (ix, (offset, anchor)) in offsets.iter().zip(anchors).enumerate() {
4311            if ix > 0 && *offset == MultiBufferOffset(252) && offset > &offsets[ix - 1] {
4312                let prev_anchor = left_anchors[ix - 1];
4313                assert!(
4314                    anchor.cmp(&prev_anchor, snapshot).is_gt(),
4315                    "anchor({}, {bias:?}).cmp(&anchor({}, {bias:?}).is_gt()",
4316                    offsets[ix],
4317                    offsets[ix - 1],
4318                );
4319                assert!(
4320                    prev_anchor.cmp(anchor, snapshot).is_lt(),
4321                    "anchor({}, {bias:?}).cmp(&anchor({}, {bias:?}).is_lt()",
4322                    offsets[ix - 1],
4323                    offsets[ix],
4324                );
4325            }
4326        }
4327    }
4328
4329    if let Some((buffer, offset)) = snapshot.point_to_buffer_offset(snapshot.max_point()) {
4330        assert!(offset.0 <= buffer.len());
4331    }
4332    if let Some((buffer, point, _)) = snapshot.point_to_buffer_point(snapshot.max_point()) {
4333        assert!(point <= buffer.max_point());
4334    }
4335}
4336
4337fn assert_line_indents(snapshot: &MultiBufferSnapshot) {
4338    let max_row = snapshot.max_point().row;
4339    let buffer_id = snapshot.excerpts().next().unwrap().1.remote_id();
4340    let text = text::Buffer::new(ReplicaId::LOCAL, buffer_id, snapshot.text());
4341    let mut line_indents = text
4342        .line_indents_in_row_range(0..max_row + 1)
4343        .collect::<Vec<_>>();
4344    for start_row in 0..snapshot.max_point().row {
4345        pretty_assertions::assert_eq!(
4346            snapshot
4347                .line_indents(MultiBufferRow(start_row), |_| true)
4348                .map(|(row, indent, _)| (row.0, indent))
4349                .collect::<Vec<_>>(),
4350            &line_indents[(start_row as usize)..],
4351            "line_indents({start_row})"
4352        );
4353    }
4354
4355    line_indents.reverse();
4356    pretty_assertions::assert_eq!(
4357        snapshot
4358            .reversed_line_indents(MultiBufferRow(max_row), |_| true)
4359            .map(|(row, indent, _)| (row.0, indent))
4360            .collect::<Vec<_>>(),
4361        &line_indents[..],
4362        "reversed_line_indents({max_row})"
4363    );
4364}
4365
4366#[gpui::test]
4367fn test_new_empty_buffer_uses_untitled_title(cx: &mut App) {
4368    let buffer = cx.new(|cx| Buffer::local("", cx));
4369    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4370
4371    assert_eq!(multibuffer.read(cx).title(cx), "untitled");
4372}
4373
4374#[gpui::test]
4375fn test_new_empty_buffer_uses_untitled_title_when_only_contains_whitespace(cx: &mut App) {
4376    let buffer = cx.new(|cx| Buffer::local("\n ", cx));
4377    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4378
4379    assert_eq!(multibuffer.read(cx).title(cx), "untitled");
4380}
4381
4382#[gpui::test]
4383fn test_new_empty_buffer_takes_first_line_for_title(cx: &mut App) {
4384    let buffer = cx.new(|cx| Buffer::local("Hello World\nSecond line", cx));
4385    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4386
4387    assert_eq!(multibuffer.read(cx).title(cx), "Hello World");
4388}
4389
4390#[gpui::test]
4391fn test_new_empty_buffer_takes_trimmed_first_line_for_title(cx: &mut App) {
4392    let buffer = cx.new(|cx| Buffer::local("\nHello, World ", cx));
4393    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4394
4395    assert_eq!(multibuffer.read(cx).title(cx), "Hello, World");
4396}
4397
4398#[gpui::test]
4399fn test_new_empty_buffer_uses_truncated_first_line_for_title(cx: &mut App) {
4400    let title = "aaaaaaaaaabbbbbbbbbbccccccccccddddddddddeeeeeeeeee";
4401    let title_after = "aaaaaaaaaabbbbbbbbbbccccccccccdddddddddd";
4402    let buffer = cx.new(|cx| Buffer::local(title, cx));
4403    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4404
4405    assert_eq!(multibuffer.read(cx).title(cx), title_after);
4406}
4407
4408#[gpui::test]
4409fn test_new_empty_buffer_uses_truncated_first_line_for_title_after_merging_adjacent_spaces(
4410    cx: &mut App,
4411) {
4412    let title = "aaaaaaaaaabbbbbbbbbb    ccccccccccddddddddddeeeeeeeeee";
4413    let title_after = "aaaaaaaaaabbbbbbbbbb ccccccccccddddddddd";
4414    let buffer = cx.new(|cx| Buffer::local(title, cx));
4415    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4416
4417    assert_eq!(multibuffer.read(cx).title(cx), title_after);
4418}
4419
4420#[gpui::test]
4421fn test_new_empty_buffers_title_can_be_set(cx: &mut App) {
4422    let buffer = cx.new(|cx| Buffer::local("Hello World", cx));
4423    let multibuffer = cx.new(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4424    assert_eq!(multibuffer.read(cx).title(cx), "Hello World");
4425
4426    multibuffer.update(cx, |multibuffer, cx| {
4427        multibuffer.set_title("Hey".into(), cx)
4428    });
4429    assert_eq!(multibuffer.read(cx).title(cx), "Hey");
4430}
4431
4432#[gpui::test(iterations = 100)]
4433fn test_random_chunk_bitmaps(cx: &mut App, mut rng: StdRng) {
4434    let multibuffer = if rng.random() {
4435        let len = rng.random_range(0..10000);
4436        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
4437        let buffer = cx.new(|cx| Buffer::local(text, cx));
4438        cx.new(|cx| MultiBuffer::singleton(buffer, cx))
4439    } else {
4440        MultiBuffer::build_random(&mut rng, cx)
4441    };
4442
4443    let snapshot = multibuffer.read(cx).snapshot(cx);
4444
4445    let chunks = snapshot.chunks(MultiBufferOffset(0)..snapshot.len(), false);
4446
4447    for chunk in chunks {
4448        let chunk_text = chunk.text;
4449        let chars_bitmap = chunk.chars;
4450        let tabs_bitmap = chunk.tabs;
4451
4452        if chunk_text.is_empty() {
4453            assert_eq!(
4454                chars_bitmap, 0,
4455                "Empty chunk should have empty chars bitmap"
4456            );
4457            assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
4458            continue;
4459        }
4460
4461        assert!(
4462            chunk_text.len() <= 128,
4463            "Chunk text length {} exceeds 128 bytes",
4464            chunk_text.len()
4465        );
4466
4467        // Verify chars bitmap
4468        let char_indices = chunk_text
4469            .char_indices()
4470            .map(|(i, _)| i)
4471            .collect::<Vec<_>>();
4472
4473        for byte_idx in 0..chunk_text.len() {
4474            let should_have_bit = char_indices.contains(&byte_idx);
4475            let has_bit = chars_bitmap & (1 << byte_idx) != 0;
4476
4477            if has_bit != should_have_bit {
4478                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
4479                eprintln!("Char indices: {:?}", char_indices);
4480                eprintln!("Chars bitmap: {:#b}", chars_bitmap);
4481            }
4482
4483            assert_eq!(
4484                has_bit, should_have_bit,
4485                "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
4486                byte_idx, chunk_text, should_have_bit, has_bit
4487            );
4488        }
4489
4490        for (byte_idx, byte) in chunk_text.bytes().enumerate() {
4491            let is_tab = byte == b'\t';
4492            let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
4493
4494            if has_bit != is_tab {
4495                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
4496                eprintln!("Tabs bitmap: {:#b}", tabs_bitmap);
4497                assert_eq!(
4498                    has_bit, is_tab,
4499                    "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
4500                    byte_idx, chunk_text, byte as char, is_tab, has_bit
4501                );
4502            }
4503        }
4504    }
4505}
4506
4507#[gpui::test(iterations = 10)]
4508fn test_random_chunk_bitmaps_with_diffs(cx: &mut App, mut rng: StdRng) {
4509    let settings_store = SettingsStore::test(cx);
4510    cx.set_global(settings_store);
4511    use buffer_diff::BufferDiff;
4512    use util::RandomCharIter;
4513
4514    let multibuffer = if rng.random() {
4515        let len = rng.random_range(100..10000);
4516        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
4517        let buffer = cx.new(|cx| Buffer::local(text, cx));
4518        cx.new(|cx| MultiBuffer::singleton(buffer, cx))
4519    } else {
4520        MultiBuffer::build_random(&mut rng, cx)
4521    };
4522
4523    let _diff_count = rng.random_range(1..5);
4524    let mut diffs = Vec::new();
4525
4526    multibuffer.update(cx, |multibuffer, cx| {
4527        for buffer_id in multibuffer.excerpt_buffer_ids() {
4528            if rng.random_bool(0.7) {
4529                if let Some(buffer_handle) = multibuffer.buffer(buffer_id) {
4530                    let buffer_text = buffer_handle.read(cx).text();
4531                    let mut base_text = String::new();
4532
4533                    for line in buffer_text.lines() {
4534                        if rng.random_bool(0.3) {
4535                            continue;
4536                        } else if rng.random_bool(0.3) {
4537                            let line_len = rng.random_range(0..50);
4538                            let modified_line = RandomCharIter::new(&mut rng)
4539                                .take(line_len)
4540                                .collect::<String>();
4541                            base_text.push_str(&modified_line);
4542                            base_text.push('\n');
4543                        } else {
4544                            base_text.push_str(line);
4545                            base_text.push('\n');
4546                        }
4547                    }
4548
4549                    if rng.random_bool(0.5) {
4550                        let extra_lines = rng.random_range(1..5);
4551                        for _ in 0..extra_lines {
4552                            let line_len = rng.random_range(0..50);
4553                            let extra_line = RandomCharIter::new(&mut rng)
4554                                .take(line_len)
4555                                .collect::<String>();
4556                            base_text.push_str(&extra_line);
4557                            base_text.push('\n');
4558                        }
4559                    }
4560
4561                    let diff = cx.new(|cx| {
4562                        BufferDiff::new_with_base_text(
4563                            &base_text,
4564                            &buffer_handle.read(cx).text_snapshot(),
4565                            cx,
4566                        )
4567                    });
4568                    diffs.push(diff.clone());
4569                    multibuffer.add_diff(diff, cx);
4570                }
4571            }
4572        }
4573    });
4574
4575    multibuffer.update(cx, |multibuffer, cx| {
4576        if rng.random_bool(0.5) {
4577            multibuffer.set_all_diff_hunks_expanded(cx);
4578        } else {
4579            let snapshot = multibuffer.snapshot(cx);
4580            let text = snapshot.text();
4581
4582            let mut ranges = Vec::new();
4583            for _ in 0..rng.random_range(1..5) {
4584                if snapshot.len().0 == 0 {
4585                    break;
4586                }
4587
4588                let diff_size = rng.random_range(5..1000);
4589                let mut start = rng.random_range(0..snapshot.len().0);
4590
4591                while !text.is_char_boundary(start) {
4592                    start = start.saturating_sub(1);
4593                }
4594
4595                let mut end = rng.random_range(start..snapshot.len().0.min(start + diff_size));
4596
4597                while !text.is_char_boundary(end) {
4598                    end = end.saturating_add(1);
4599                }
4600                let start_anchor = snapshot.anchor_after(MultiBufferOffset(start));
4601                let end_anchor = snapshot.anchor_before(MultiBufferOffset(end));
4602                ranges.push(start_anchor..end_anchor);
4603            }
4604            multibuffer.expand_diff_hunks(ranges, cx);
4605        }
4606    });
4607
4608    let snapshot = multibuffer.read(cx).snapshot(cx);
4609
4610    let chunks = snapshot.chunks(MultiBufferOffset(0)..snapshot.len(), false);
4611
4612    for chunk in chunks {
4613        let chunk_text = chunk.text;
4614        let chars_bitmap = chunk.chars;
4615        let tabs_bitmap = chunk.tabs;
4616
4617        if chunk_text.is_empty() {
4618            assert_eq!(
4619                chars_bitmap, 0,
4620                "Empty chunk should have empty chars bitmap"
4621            );
4622            assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
4623            continue;
4624        }
4625
4626        assert!(
4627            chunk_text.len() <= 128,
4628            "Chunk text length {} exceeds 128 bytes",
4629            chunk_text.len()
4630        );
4631
4632        let char_indices = chunk_text
4633            .char_indices()
4634            .map(|(i, _)| i)
4635            .collect::<Vec<_>>();
4636
4637        for byte_idx in 0..chunk_text.len() {
4638            let should_have_bit = char_indices.contains(&byte_idx);
4639            let has_bit = chars_bitmap & (1 << byte_idx) != 0;
4640
4641            if has_bit != should_have_bit {
4642                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
4643                eprintln!("Char indices: {:?}", char_indices);
4644                eprintln!("Chars bitmap: {:#b}", chars_bitmap);
4645            }
4646
4647            assert_eq!(
4648                has_bit, should_have_bit,
4649                "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
4650                byte_idx, chunk_text, should_have_bit, has_bit
4651            );
4652        }
4653
4654        for (byte_idx, byte) in chunk_text.bytes().enumerate() {
4655            let is_tab = byte == b'\t';
4656            let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
4657
4658            if has_bit != is_tab {
4659                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
4660                eprintln!("Tabs bitmap: {:#b}", tabs_bitmap);
4661                assert_eq!(
4662                    has_bit, is_tab,
4663                    "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
4664                    byte_idx, chunk_text, byte as char, is_tab, has_bit
4665                );
4666            }
4667        }
4668    }
4669}
4670
4671fn collect_word_diffs(
4672    base_text: &str,
4673    modified_text: &str,
4674    cx: &mut TestAppContext,
4675) -> Vec<String> {
4676    let buffer = cx.new(|cx| Buffer::local(modified_text, cx));
4677    let diff = cx
4678        .new(|cx| BufferDiff::new_with_base_text(base_text, &buffer.read(cx).text_snapshot(), cx));
4679    cx.run_until_parked();
4680
4681    let multibuffer = cx.new(|cx| {
4682        let mut multibuffer = MultiBuffer::singleton(buffer.clone(), cx);
4683        multibuffer.add_diff(diff.clone(), cx);
4684        multibuffer
4685    });
4686
4687    multibuffer.update(cx, |multibuffer, cx| {
4688        multibuffer.expand_diff_hunks(vec![Anchor::min()..Anchor::max()], cx);
4689    });
4690
4691    let snapshot = multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
4692    let text = snapshot.text();
4693
4694    snapshot
4695        .diff_hunks()
4696        .flat_map(|hunk| hunk.word_diffs)
4697        .map(|range| text[range.start.0..range.end.0].to_string())
4698        .collect()
4699}
4700
4701#[gpui::test]
4702async fn test_word_diff_simple_replacement(cx: &mut TestAppContext) {
4703    let settings_store = cx.update(|cx| SettingsStore::test(cx));
4704    cx.set_global(settings_store);
4705
4706    let base_text = "hello world foo bar\n";
4707    let modified_text = "hello WORLD foo BAR\n";
4708
4709    let word_diffs = collect_word_diffs(base_text, modified_text, cx);
4710
4711    assert_eq!(word_diffs, vec!["world", "bar", "WORLD", "BAR"]);
4712}
4713
4714#[gpui::test]
4715async fn test_word_diff_white_space(cx: &mut TestAppContext) {
4716    let settings_store = cx.update(|cx| SettingsStore::test(cx));
4717    cx.set_global(settings_store);
4718
4719    let base_text = "hello world foo bar\n";
4720    let modified_text = "    hello world foo bar\n";
4721
4722    let word_diffs = collect_word_diffs(base_text, modified_text, cx);
4723
4724    assert_eq!(word_diffs, vec!["    "]);
4725}
4726
4727#[gpui::test]
4728async fn test_word_diff_consecutive_modified_lines(cx: &mut TestAppContext) {
4729    let settings_store = cx.update(|cx| SettingsStore::test(cx));
4730    cx.set_global(settings_store);
4731
4732    let base_text = "aaa bbb\nccc ddd\n";
4733    let modified_text = "aaa BBB\nccc DDD\n";
4734
4735    let word_diffs = collect_word_diffs(base_text, modified_text, cx);
4736
4737    assert_eq!(
4738        word_diffs,
4739        vec!["bbb", "ddd", "BBB", "DDD"],
4740        "consecutive modified lines should produce word diffs when line counts match"
4741    );
4742}
4743
4744#[gpui::test]
4745async fn test_word_diff_modified_lines_with_deletion_between(cx: &mut TestAppContext) {
4746    let settings_store = cx.update(|cx| SettingsStore::test(cx));
4747    cx.set_global(settings_store);
4748
4749    let base_text = "aaa bbb\ndeleted line\nccc ddd\n";
4750    let modified_text = "aaa BBB\nccc DDD\n";
4751
4752    let word_diffs = collect_word_diffs(base_text, modified_text, cx);
4753
4754    assert_eq!(
4755        word_diffs,
4756        Vec::<String>::new(),
4757        "modified lines with a deleted line between should not produce word diffs"
4758    );
4759}
4760
4761#[gpui::test]
4762async fn test_word_diff_disabled(cx: &mut TestAppContext) {
4763    let settings_store = cx.update(|cx| {
4764        let mut settings_store = SettingsStore::test(cx);
4765        settings_store.update_user_settings(cx, |settings| {
4766            settings.project.all_languages.defaults.word_diff_enabled = Some(false);
4767        });
4768        settings_store
4769    });
4770    cx.set_global(settings_store);
4771
4772    let base_text = "hello world\n";
4773    let modified_text = "hello WORLD\n";
4774
4775    let word_diffs = collect_word_diffs(base_text, modified_text, cx);
4776
4777    assert_eq!(
4778        word_diffs,
4779        Vec::<String>::new(),
4780        "word diffs should be empty when disabled"
4781    );
4782}
4783
4784/// Tests `excerpt_containing` and `excerpts_for_range` (functions mapping multi-buffer text-coordinates to excerpts)
4785#[gpui::test]
4786fn test_excerpts_containment_functions(cx: &mut App) {
4787    // Multibuffer content for these tests:
4788    //    0123
4789    // 0: aa0
4790    // 1: aa1
4791    //    -----
4792    // 2: bb0
4793    // 3: bb1
4794    //    -----MultiBufferOffset(0)..
4795    // 4: cc0
4796
4797    let buffer_1 = cx.new(|cx| Buffer::local("aa0\naa1", cx));
4798    let buffer_2 = cx.new(|cx| Buffer::local("bb0\nbb1", cx));
4799    let buffer_3 = cx.new(|cx| Buffer::local("cc0", cx));
4800
4801    let multibuffer = cx.new(|_| MultiBuffer::new(Capability::ReadWrite));
4802
4803    let (excerpt_1_id, excerpt_2_id, excerpt_3_id) = multibuffer.update(cx, |multibuffer, cx| {
4804        let excerpt_1_id = multibuffer.push_excerpts(
4805            buffer_1.clone(),
4806            [ExcerptRange::new(Point::new(0, 0)..Point::new(1, 3))],
4807            cx,
4808        )[0];
4809
4810        let excerpt_2_id = multibuffer.push_excerpts(
4811            buffer_2.clone(),
4812            [ExcerptRange::new(Point::new(0, 0)..Point::new(1, 3))],
4813            cx,
4814        )[0];
4815
4816        let excerpt_3_id = multibuffer.push_excerpts(
4817            buffer_3.clone(),
4818            [ExcerptRange::new(Point::new(0, 0)..Point::new(0, 3))],
4819            cx,
4820        )[0];
4821
4822        (excerpt_1_id, excerpt_2_id, excerpt_3_id)
4823    });
4824
4825    let snapshot = multibuffer.read(cx).snapshot(cx);
4826
4827    assert_eq!(snapshot.text(), "aa0\naa1\nbb0\nbb1\ncc0");
4828
4829    //// Test `excerpts_for_range`
4830
4831    let p00 = snapshot.point_to_offset(Point::new(0, 0));
4832    let p10 = snapshot.point_to_offset(Point::new(1, 0));
4833    let p20 = snapshot.point_to_offset(Point::new(2, 0));
4834    let p23 = snapshot.point_to_offset(Point::new(2, 3));
4835    let p13 = snapshot.point_to_offset(Point::new(1, 3));
4836    let p40 = snapshot.point_to_offset(Point::new(4, 0));
4837    let p43 = snapshot.point_to_offset(Point::new(4, 3));
4838
4839    let excerpts: Vec<_> = snapshot.excerpts_for_range(p00..p00).collect();
4840    assert_eq!(excerpts.len(), 1);
4841    assert_eq!(excerpts[0].id, excerpt_1_id);
4842
4843    // Cursor at very end of excerpt 3
4844    let excerpts: Vec<_> = snapshot.excerpts_for_range(p43..p43).collect();
4845    assert_eq!(excerpts.len(), 1);
4846    assert_eq!(excerpts[0].id, excerpt_3_id);
4847
4848    let excerpts: Vec<_> = snapshot.excerpts_for_range(p00..p23).collect();
4849    assert_eq!(excerpts.len(), 2);
4850    assert_eq!(excerpts[0].id, excerpt_1_id);
4851    assert_eq!(excerpts[1].id, excerpt_2_id);
4852
4853    // This range represent an selection with end-point just inside excerpt_2
4854    // Today we only expand the first excerpt, but another interpretation that
4855    // we could consider is expanding both here
4856    let excerpts: Vec<_> = snapshot.excerpts_for_range(p10..p20).collect();
4857    assert_eq!(excerpts.len(), 1);
4858    assert_eq!(excerpts[0].id, excerpt_1_id);
4859
4860    //// Test that `excerpts_for_range` and `excerpt_containing` agree for all single offsets (cursor positions)
4861    for offset in 0..=snapshot.len().0 {
4862        let offset = MultiBufferOffset(offset);
4863        let excerpts_for_range: Vec<_> = snapshot.excerpts_for_range(offset..offset).collect();
4864        assert_eq!(
4865            excerpts_for_range.len(),
4866            1,
4867            "Expected exactly one excerpt for offset {offset}",
4868        );
4869
4870        let excerpt_containing = snapshot.excerpt_containing(offset..offset);
4871        assert!(
4872            excerpt_containing.is_some(),
4873            "Expected excerpt_containing to find excerpt for offset {offset}",
4874        );
4875
4876        assert_eq!(
4877            excerpts_for_range[0].id,
4878            excerpt_containing.unwrap().id(),
4879            "excerpts_for_range and excerpt_containing should agree for offset {offset}",
4880        );
4881    }
4882
4883    //// Test `excerpt_containing` behavior with ranges:
4884
4885    // Ranges intersecting a single-excerpt
4886    let containing = snapshot.excerpt_containing(p00..p13);
4887    assert!(containing.is_some());
4888    assert_eq!(containing.unwrap().id(), excerpt_1_id);
4889
4890    // Ranges intersecting multiple excerpts (should return None)
4891    let containing = snapshot.excerpt_containing(p20..p40);
4892    assert!(
4893        containing.is_none(),
4894        "excerpt_containing should return None for ranges spanning multiple excerpts"
4895    );
4896}