1//! Test support for GPUI.
2//!
3//! GPUI provides first-class support for testing, which includes a macro to run test that rely on having a context,
4//! and a test implementation of the `ForegroundExecutor` and `BackgroundExecutor` which ensure that your tests run
5//! deterministically even in the face of arbitrary parallelism.
6//!
7//! The output of the `gpui::test` macro is understood by other rust test runners, so you can use it with `cargo test`
8//! or `cargo-nextest`, or another runner of your choice.
9//!
10//! To make it possible to test collaborative user interfaces (like Zed) you can ask for as many different contexts
11//! as you need.
12//!
13//! ## Example
14//!
15//! ```
16//! use gpui;
17//!
18//! #[gpui::test]
19//! async fn test_example(cx: &TestAppContext) {
20//! assert!(true)
21//! }
22//!
23//! #[gpui::test]
24//! async fn test_collaboration_example(cx_a: &TestAppContext, cx_b: &TestAppContext) {
25//! assert!(true)
26//! }
27//! ```
28use crate::{Entity, Subscription, TestAppContext, TestDispatcher};
29use futures::StreamExt as _;
30use rand::prelude::*;
31use smol::channel;
32use std::{
33 env,
34 panic::{self, RefUnwindSafe},
35};
36
37/// Run the given test function with the configured parameters.
38/// This is intended for use with the `gpui::test` macro
39/// and generally should not be used directly.
40pub fn run_test(
41 mut num_iterations: u64,
42 max_retries: usize,
43 test_fn: &mut (dyn RefUnwindSafe + Fn(TestDispatcher, u64)),
44 on_fail_fn: Option<fn()>,
45) {
46 let starting_seed = env::var("SEED")
47 .map(|seed| seed.parse().expect("invalid SEED variable"))
48 .unwrap_or(0);
49 if let Ok(iterations) = env::var("ITERATIONS") {
50 num_iterations = iterations.parse().expect("invalid ITERATIONS variable");
51 }
52 let is_randomized = num_iterations > 1;
53
54 for seed in starting_seed..starting_seed + num_iterations {
55 let mut retry = 0;
56 loop {
57 if is_randomized {
58 eprintln!("seed = {seed}");
59 }
60 let result = panic::catch_unwind(|| {
61 let dispatcher = TestDispatcher::new(StdRng::seed_from_u64(seed));
62 test_fn(dispatcher, seed);
63 });
64
65 match result {
66 Ok(_) => break,
67 Err(error) => {
68 if retry < max_retries {
69 println!("retrying: attempt {}", retry);
70 retry += 1;
71 } else {
72 if is_randomized {
73 eprintln!("failing seed: {}", seed);
74 }
75 if let Some(f) = on_fail_fn {
76 f()
77 }
78 panic::resume_unwind(error);
79 }
80 }
81 }
82 }
83 }
84}
85
86/// A test struct for converting an observation callback into a stream.
87pub struct Observation<T> {
88 rx: channel::Receiver<T>,
89 _subscription: Subscription,
90}
91
92impl<T: 'static> futures::Stream for Observation<T> {
93 type Item = T;
94
95 fn poll_next(
96 mut self: std::pin::Pin<&mut Self>,
97 cx: &mut std::task::Context<'_>,
98 ) -> std::task::Poll<Option<Self::Item>> {
99 self.rx.poll_next_unpin(cx)
100 }
101}
102
103/// observe returns a stream of the change events from the given `View` or `Model`
104pub fn observe<T: 'static>(entity: &impl Entity<T>, cx: &mut TestAppContext) -> Observation<()> {
105 let (tx, rx) = smol::channel::unbounded();
106 let _subscription = cx.update(|cx| {
107 cx.observe(entity, move |_, _| {
108 let _ = smol::block_on(tx.send(()));
109 })
110 });
111
112 Observation { rx, _subscription }
113}