WIP: improve move and link handling around 'root paths', currently very incorrect and in need of a deeper rework

Mikayla created 2 years ago

Change summary

crates/channel/src/channel_store/channel_index.rs |  66 ++-
crates/collab/src/db/queries/channels.rs          |  38 -
crates/collab/src/rpc.rs                          |  42 +
crates/collab/src/tests/channel_buffer_tests.rs   |  10 
crates/collab/src/tests/channel_tests.rs          | 294 +++++++++++-----
crates/collab/src/tests/test_server.rs            |  71 ++++
6 files changed, 358 insertions(+), 163 deletions(-)

Detailed changes

crates/channel/src/channel_store/channel_index.rs

@@ -1,10 +1,11 @@
-use std::{sync::Arc, ops::Deref};
+use std::{ops::Deref, sync::Arc};
 
 use collections::HashMap;
 use rpc::proto;
-use serde_derive::{Serialize, Deserialize};
+use serde_derive::{Deserialize, Serialize};
 
-use crate::{ChannelId, Channel};
+
+use crate::{Channel, ChannelId};
 
 pub type ChannelsById = HashMap<ChannelId, Arc<Channel>>;
 
@@ -21,9 +22,7 @@ impl Deref for ChannelPath {
 
 impl ChannelPath {
     pub fn parent_id(&self) -> Option<ChannelId> {
-        self.0.len().checked_sub(2).map(|i| {
-            self.0[i]
-        })
+        self.0.len().checked_sub(2).map(|i| self.0[i])
     }
 }
 
@@ -39,7 +38,6 @@ pub struct ChannelIndex {
     channels_by_id: ChannelsById,
 }
 
-
 impl ChannelIndex {
     pub fn by_id(&self) -> &ChannelsById {
         &self.channels_by_id
@@ -62,24 +60,53 @@ impl ChannelIndex {
         self.paths.iter()
     }
 
-    /// Remove the given edge from this index. This will not remove the channel
-    /// and may result in dangling channels.
-    pub fn delete_edge(&mut self, parent_id: ChannelId, channel_id: ChannelId) {
-        self.paths.retain(|path| {
-            !path
-                .windows(2)
-                .any(|window| window == [parent_id, channel_id])
-        });
+    /// Remove the given edge from this index. This will not remove the channel.
+    /// If this operation would result in a dangling edge, re-insert it.
+    pub fn delete_edge(&mut self, parent_id: Option<ChannelId>, channel_id: ChannelId) {
+        if let Some(parent_id) = parent_id {
+            self.paths.retain(|path| {
+                !path
+                    .windows(2)
+                    .any(|window| window == [parent_id, channel_id])
+            });
+        } else {
+            self.paths.retain(|path| path.first() != Some(&channel_id));
+        }
+
+        // Ensure that there is at least one channel path in the index
+        if !self
+            .paths
+            .iter()
+            .any(|path| path.iter().any(|id| id == &channel_id))
+        {
+            let path = ChannelPath(Arc::from([channel_id]));
+            let current_item: Vec<_> =
+                channel_path_sorting_key(&path, &self.channels_by_id).collect();
+            match self.paths.binary_search_by(|channel_path| {
+                current_item
+                    .iter()
+                    .copied()
+                    .cmp(channel_path_sorting_key(channel_path, &self.channels_by_id))
+            }) {
+                Ok(ix) => self.paths.insert(ix, path),
+                Err(ix) => self.paths.insert(ix, path),
+            }
+        }
     }
 
     /// Delete the given channels from this index.
     pub fn delete_channels(&mut self, channels: &[ChannelId]) {
-        self.channels_by_id.retain(|channel_id, _| !channels.contains(channel_id));
-        self.paths.retain(|channel_path| !channel_path.iter().any(|channel_id| {channels.contains(channel_id)}))
+        self.channels_by_id
+            .retain(|channel_id, _| !channels.contains(channel_id));
+        self.paths.retain(|channel_path| {
+            !channel_path
+                .iter()
+                .any(|channel_id| channels.contains(channel_id))
+        })
     }
 
     /// Upsert one or more channels into this index.
-    pub fn start_upsert(& mut self) -> ChannelPathsUpsertGuard {
+    pub fn start_upsert(&mut self) -> ChannelPathsUpsertGuard {
         ChannelPathsUpsertGuard {
             paths: &mut self.paths,
             channels_by_id: &mut self.channels_by_id,
@@ -90,7 +117,7 @@ impl ChannelIndex {
 /// A guard for ensuring that the paths index maintains its sort and uniqueness
 /// invariants after a series of insertions
 pub struct ChannelPathsUpsertGuard<'a> {
-    paths:  &'a mut Vec<ChannelPath>,
+    paths: &'a mut Vec<ChannelPath>,
     channels_by_id: &'a mut ChannelsById,
 }
 
@@ -151,7 +178,6 @@ impl<'a> Drop for ChannelPathsUpsertGuard<'a> {
     }
 }
 
-
 fn channel_path_sorting_key<'a>(
     path: &'a [ChannelId],
     channels_by_id: &'a ChannelsById,

crates/collab/src/db/queries/channels.rs

@@ -870,36 +870,22 @@ impl Database {
         &self,
         user: UserId,
         channel: ChannelId,
-        from: Option<ChannelId>,
+        from: ChannelId,
         tx: &DatabaseTransaction,
     ) -> Result<()> {
-        if let Some(from) = from {
-            self.check_user_is_channel_admin(from, user, &*tx).await?;
+        self.check_user_is_channel_admin(from, user, &*tx).await?;
 
-            let sql = r#"
+        let sql = r#"
                 DELETE FROM channel_paths
                 WHERE
                     id_path LIKE '%' || $1 || '/' || $2 || '%'
             "#;
-            let channel_paths_stmt = Statement::from_sql_and_values(
-                self.pool.get_database_backend(),
-                sql,
-                [from.to_proto().into(), channel.to_proto().into()],
-            );
-            tx.execute(channel_paths_stmt).await?;
-        } else {
-            let sql = r#"
-                DELETE FROM channel_paths
-                WHERE
-                    id_path = '/' || $1 || '/'
-            "#;
-            let channel_paths_stmt = Statement::from_sql_and_values(
-                self.pool.get_database_backend(),
-                sql,
-                [channel.to_proto().into()],
-            );
-            tx.execute(channel_paths_stmt).await?;
-        }
+        let channel_paths_stmt = Statement::from_sql_and_values(
+            self.pool.get_database_backend(),
+            sql,
+            [from.to_proto().into(), channel.to_proto().into()],
+        );
+        tx.execute(channel_paths_stmt).await?;
 
         // Make sure that there is always at least one path to the channel
         let sql = r#"
@@ -929,7 +915,7 @@ impl Database {
         &self,
         user: UserId,
         channel: ChannelId,
-        from: Option<ChannelId>,
+        from: ChannelId,
         to: ChannelId,
     ) -> Result<Vec<Channel>> {
         self.transaction(|tx| async move {
@@ -941,6 +927,10 @@ impl Database {
             self.unlink_channel_internal(user, channel, from, &*tx)
                 .await?;
 
+            dbg!(channel_path::Entity::find().all(&*tx).await);
+
+            dbg!(&moved_channels);
+
             Ok(moved_channels)
         })
         .await

crates/collab/src/rpc.rs

@@ -2435,22 +2435,23 @@ async fn unlink_channel(
     let db = session.db().await;
     let channel_id = ChannelId::from_proto(request.channel_id);
     let from = request.from.map(ChannelId::from_proto);
+
+    // Get the members before we remove it, so we know who to notify
+    let members = db.get_channel_members(channel_id).await?;
+
     db.unlink_channel(session.user_id, channel_id, from).await?;
 
-    if let Some(from_parent) = from {
-        let members = db.get_channel_members(from_parent).await?;
-        let update = proto::UpdateChannels {
-            delete_channel_edge: vec![proto::ChannelEdge {
-                channel_id: channel_id.to_proto(),
-                parent_id: from_parent.to_proto(),
-            }],
-            ..Default::default()
-        };
-        let connection_pool = session.connection_pool().await;
-        for member_id in members {
-            for connection_id in connection_pool.user_connection_ids(member_id) {
-                session.peer.send(connection_id, update.clone())?;
-            }
+    let update = proto::UpdateChannels {
+        delete_channel_edge: vec![proto::ChannelEdge {
+            channel_id: channel_id.to_proto(),
+            parent_id: from.map(ChannelId::to_proto),
+        }],
+        ..Default::default()
+    };
+    let connection_pool = session.connection_pool().await;
+    for member_id in members {
+        for connection_id in connection_pool.user_connection_ids(member_id) {
+            session.peer.send(connection_id, update.clone())?;
         }
     }
 
@@ -2468,16 +2469,24 @@ async fn move_channel(
     let channel_id = ChannelId::from_proto(request.channel_id);
     let from_parent = request.from.map(ChannelId::from_proto);
     let to = ChannelId::from_proto(request.to);
+
+    let mut members = db.get_channel_members(channel_id).await?;
+
     let channels_to_send: Vec<Channel> = db
         .move_channel(session.user_id, channel_id, from_parent, to)
         .await?;
 
+    let members_after =  db.get_channel_members(channel_id).await?;
+
+    members.extend(members_after);
+    members.sort();
+    members.dedup();
+
     if let Some(from_parent) = from_parent {
-        let members = db.get_channel_members(from_parent).await?;
         let update = proto::UpdateChannels {
             delete_channel_edge: vec![proto::ChannelEdge {
                 channel_id: channel_id.to_proto(),
-                parent_id: from_parent.to_proto(),
+                parent_id: Some(from_parent.to_proto()),
             }],
             ..Default::default()
         };
@@ -2489,7 +2498,6 @@ async fn move_channel(
         }
     }
 
-    let members = db.get_channel_members(to).await?;
     let connection_pool = session.connection_pool().await;
     let update = proto::UpdateChannels {
         channels: channels_to_send

crates/collab/src/tests/channel_buffer_tests.rs

@@ -25,7 +25,7 @@ async fn test_core_channel_buffers(
     let client_b = server.create_client(cx_b, "user_b").await;
 
     let channel_id = server
-        .make_channel("zed", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .make_channel("zed", None, (&client_a, cx_a), &mut [(&client_b, cx_b)])
         .await;
 
     // Client A joins the channel buffer
@@ -135,6 +135,7 @@ async fn test_channel_buffer_replica_ids(
     let channel_id = server
         .make_channel(
             "the-channel",
+            None,
             (&client_a, cx_a),
             &mut [(&client_b, cx_b), (&client_c, cx_c)],
         )
@@ -279,7 +280,7 @@ async fn test_reopen_channel_buffer(deterministic: Arc<Deterministic>, cx_a: &mu
     let client_a = server.create_client(cx_a, "user_a").await;
 
     let channel_id = server
-        .make_channel("the-channel", (&client_a, cx_a), &mut [])
+        .make_channel("the-channel", None, (&client_a, cx_a), &mut [])
         .await;
 
     let channel_buffer_1 = client_a
@@ -341,7 +342,7 @@ async fn test_channel_buffer_disconnect(
     let client_b = server.create_client(cx_b, "user_b").await;
 
     let channel_id = server
-        .make_channel("the-channel", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .make_channel("the-channel", None, (&client_a, cx_a), &mut [(&client_b, cx_b)])
         .await;
 
     let channel_buffer_a = client_a
@@ -411,7 +412,7 @@ async fn test_rejoin_channel_buffer(
     let client_b = server.create_client(cx_b, "user_b").await;
 
     let channel_id = server
-        .make_channel("the-channel", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .make_channel("the-channel", None, (&client_a, cx_a), &mut [(&client_b, cx_b)])
         .await;
 
     let channel_buffer_a = client_a
@@ -491,6 +492,7 @@ async fn test_channel_buffers_and_server_restarts(
     let channel_id = server
         .make_channel(
             "the-channel",
+            None,
             (&client_a, cx_a),
             &mut [(&client_b, cx_b), (&client_c, cx_c)],
         )

crates/collab/src/tests/channel_tests.rs

@@ -326,7 +326,7 @@ async fn test_joining_channel_ancestor_member(
     let client_b = server.create_client(cx_b, "user_b").await;
 
     let parent_id = server
-        .make_channel("parent", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .make_channel("parent", None, (&client_a, cx_a), &mut [(&client_b, cx_b)])
         .await;
 
     let sub_id = client_a
@@ -361,6 +361,7 @@ async fn test_channel_room(
     let zed_id = server
         .make_channel(
             "zed",
+            None,
             (&client_a, cx_a),
             &mut [(&client_b, cx_b), (&client_c, cx_c)],
         )
@@ -544,9 +545,11 @@ async fn test_channel_jumping(deterministic: Arc<Deterministic>, cx_a: &mut Test
     let mut server = TestServer::start(&deterministic).await;
     let client_a = server.create_client(cx_a, "user_a").await;
 
-    let zed_id = server.make_channel("zed", (&client_a, cx_a), &mut []).await;
+    let zed_id = server
+        .make_channel("zed", None, (&client_a, cx_a), &mut [])
+        .await;
     let rust_id = server
-        .make_channel("rust", (&client_a, cx_a), &mut [])
+        .make_channel("rust", None, (&client_a, cx_a), &mut [])
         .await;
 
     let active_call_a = cx_a.read(ActiveCall::global);
@@ -597,7 +600,7 @@ async fn test_permissions_update_while_invited(
     let client_b = server.create_client(cx_b, "user_b").await;
 
     let rust_id = server
-        .make_channel("rust", (&client_a, cx_a), &mut [])
+        .make_channel("rust", None, (&client_a, cx_a), &mut [])
         .await;
 
     client_a
@@ -658,7 +661,7 @@ async fn test_channel_rename(
     let client_b = server.create_client(cx_b, "user_b").await;
 
     let rust_id = server
-        .make_channel("rust", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .make_channel("rust", None, (&client_a, cx_a), &mut [(&client_b, cx_b)])
         .await;
 
     // Rename the channel
@@ -716,6 +719,7 @@ async fn test_call_from_channel(
     let channel_id = server
         .make_channel(
             "x",
+            None,
             (&client_a, cx_a),
             &mut [(&client_b, cx_b), (&client_c, cx_c)],
         )
@@ -776,6 +780,7 @@ async fn test_lost_channel_creation(
     deterministic: Arc<Deterministic>,
     cx_a: &mut TestAppContext,
     cx_b: &mut TestAppContext,
+    cx_c: &mut TestAppContext,
 ) {
     deterministic.forbid_parking();
     let mut server = TestServer::start(&deterministic).await;
@@ -786,7 +791,9 @@ async fn test_lost_channel_creation(
         .make_contacts(&mut [(&client_a, cx_a), (&client_b, cx_b)])
         .await;
 
-    let channel_id = server.make_channel("x", (&client_a, cx_a), &mut []).await;
+    let channel_id = server
+        .make_channel("x", None, (&client_a, cx_a), &mut [])
+        .await;
 
     // Invite a member
     client_a
@@ -875,140 +882,216 @@ async fn test_lost_channel_creation(
 }
 
 #[gpui::test]
-async fn test_channel_moving(deterministic: Arc<Deterministic>, cx_a: &mut TestAppContext) {
+async fn test_channel_moving(
+    deterministic: Arc<Deterministic>,
+    cx_a: &mut TestAppContext,
+    cx_b: &mut TestAppContext,
+    cx_c: &mut TestAppContext,
+) {
     deterministic.forbid_parking();
     let mut server = TestServer::start(&deterministic).await;
     let client_a = server.create_client(cx_a, "user_a").await;
+    let client_b = server.create_client(cx_b, "user_b").await;
+    let client_c = server.create_client(cx_c, "user_c").await;
 
-    let channel_a_id = client_a
-        .channel_store()
-        .update(cx_a, |channel_store, cx| {
-            channel_store.create_channel("channel-a", None, cx)
-        })
-        .await
-        .unwrap();
-    let channel_b_id = client_a
+    let channels = server
+        .make_channel_tree(
+            &[
+                ("channel-a", None),
+                ("channel-b", Some("channel-a")),
+                ("channel-c", Some("channel-b")),
+                ("channel-d", Some("channel-c")),
+            ],
+            (&client_a, cx_a),
+        )
+        .await;
+    let channel_a_a_id = channels[0];
+    let channel_a_b_id = channels[1];
+    let channel_a_c_id = channels[2];
+    let channel_a_d_id = channels[3];
+
+    // Current shape:
+    // a - b - c - d
+    assert_channels_list_shape(
+        client_a.channel_store(),
+        cx_a,
+        &[
+            (channel_a_a_id, 0),
+            (channel_a_b_id, 1),
+            (channel_a_c_id, 2),
+            (channel_a_d_id, 3),
+        ],
+    );
+
+    client_a
         .channel_store()
         .update(cx_a, |channel_store, cx| {
-            channel_store.create_channel("channel-b", Some(channel_a_id), cx)
+            channel_store.move_channel(channel_a_d_id, Some(channel_a_c_id), channel_a_b_id, cx)
         })
         .await
         .unwrap();
-    let channel_c_id = client_a
+
+    // Current shape:
+    //       /- d
+    // a - b -- c
+    assert_channels_list_shape(
+        client_a.channel_store(),
+        cx_a,
+        &[
+            (channel_a_a_id, 0),
+            (channel_a_b_id, 1),
+            (channel_a_c_id, 2),
+            (channel_a_d_id, 2),
+        ],
+    );
+
+    client_a
         .channel_store()
         .update(cx_a, |channel_store, cx| {
-            channel_store.create_channel("channel-c", Some(channel_b_id), cx)
+            channel_store.link_channel(channel_a_d_id, channel_a_c_id, cx)
         })
         .await
         .unwrap();
 
     // Current shape:
-    // a - b - c
-    deterministic.run_until_parked();
-    assert_channels(
+    //      /------\
+    // a - b -- c -- d
+    assert_channels_list_shape(
         client_a.channel_store(),
         cx_a,
         &[
-            ExpectedChannel {
-                id: channel_a_id,
-                name: "channel-a".to_string(),
-                depth: 0,
-                user_is_admin: true,
-            },
-            ExpectedChannel {
-                id: channel_b_id,
-                name: "channel-b".to_string(),
-                depth: 1,
-                user_is_admin: true,
-            },
-            ExpectedChannel {
-                id: channel_c_id,
-                name: "channel-c".to_string(),
-                depth: 2,
-                user_is_admin: true,
-            },
+            (channel_a_a_id, 0),
+            (channel_a_b_id, 1),
+            (channel_a_c_id, 2),
+            (channel_a_d_id, 3),
+            (channel_a_d_id, 2),
         ],
     );
 
-    client_a
+    let b_channels = server
+        .make_channel_tree(
+            &[
+                ("channel-mu", None),
+                ("channel-gamma", Some("channel-mu")),
+                ("channel-epsilon", Some("channel-mu")),
+            ],
+            (&client_b, cx_b),
+        )
+        .await;
+    let channel_b_mu_id = b_channels[0];
+    let channel_b_gamma_id = b_channels[1];
+    let channel_b_epsilon_id = b_channels[2];
+
+    // Current shape for B:
+    //    /- ep
+    // mu -- ga
+    assert_channels_list_shape(
+        client_b.channel_store(),
+        cx_b,
+        &[
+            (channel_b_mu_id, 0),
+            (channel_b_gamma_id, 1),
+            (channel_b_epsilon_id, 1)
+        ],
+    );
+
+    client_a.add_admin_to_channel((&client_b, cx_b), channel_a_b_id, cx_a).await;
+    // Current shape for B:
+    //    /- ep
+    // mu -- ga
+    //  /---------\
+    // b  -- c  -- d
+    assert_channels_list_shape(
+        client_b.channel_store(),
+        cx_b,
+        &[
+            // B's old channels
+            (channel_b_mu_id, 0),
+            (channel_b_gamma_id, 1),
+            (channel_b_epsilon_id, 1),
+
+            // New channels from a
+            (channel_a_b_id, 0),
+            (channel_a_c_id, 1),
+            (channel_a_d_id, 1),
+            (channel_a_d_id, 2),
+        ],
+    );
+
+    client_b
         .channel_store()
         .update(cx_a, |channel_store, cx| {
-            channel_store.move_channel(channel_c_id, Some(channel_b_id), channel_a_id, cx)
+            channel_store.move_channel(channel_a_b_id, None, channel_b_epsilon_id, cx)
         })
         .await
         .unwrap();
 
-    // Current shape:
-    //   /- c
-    // a -- b
-    deterministic.run_until_parked();
-    assert_channels(
-        client_a.channel_store(),
-        cx_a,
+    // Current shape for B:
+    //              /---------\
+    //    /- ep -- b  -- c  -- d
+    // mu -- ga
+    assert_channels_list_shape(
+        client_b.channel_store(),
+        cx_b,
         &[
-            ExpectedChannel {
-                id: channel_a_id,
-                name: "channel-a".to_string(),
-                depth: 0,
-                user_is_admin: true,
-            },
-            ExpectedChannel {
-                id: channel_b_id,
-                name: "channel-b".to_string(),
-                depth: 1,
-                user_is_admin: true,
-            },
-            ExpectedChannel {
-                id: channel_c_id,
-                name: "channel-c".to_string(),
-                depth: 1,
-                user_is_admin: true,
-            },
+            // B's old channels
+            (channel_b_mu_id, 0),
+            (channel_b_gamma_id, 1),
+            (channel_b_epsilon_id, 1),
+
+            // New channels from a, now under epsilon
+            (channel_a_b_id, 2),
+            (channel_a_c_id, 3),
+            (channel_a_d_id, 3),
+            (channel_a_d_id, 4),
         ],
     );
 
-    client_a
+    client_b
         .channel_store()
         .update(cx_a, |channel_store, cx| {
-            channel_store.link_channel(channel_c_id, channel_b_id, cx)
+            channel_store.link_channel(channel_b_gamma_id, channel_a_b_id, cx)
         })
         .await
         .unwrap();
 
-    // Current shape:
-    //   /------\
-    // a -- b -- c
-    deterministic.run_until_parked();
-    assert_channels(
+    // Current shape for B:
+    //              /---------\
+    //    /- ep -- b  -- c  -- d
+    //   /          \
+    // mu ---------- ga
+    assert_channels_list_shape(
+        client_b.channel_store(),
+        cx_b,
+        &[
+            // B's old channels
+            (channel_b_mu_id, 0),
+            (channel_b_gamma_id, 1),
+            (channel_b_epsilon_id, 1),
+
+            // New channels from a, now under epsilon, with gamma
+            (channel_a_b_id, 2),
+            (channel_b_gamma_id, 3),
+            (channel_a_c_id, 3),
+            (channel_a_d_id, 3),
+            (channel_a_d_id, 4),
+        ],
+    );
+
+    // Current shape for A:
+    assert_channels_list_shape(
         client_a.channel_store(),
         cx_a,
         &[
-            ExpectedChannel {
-                id: channel_a_id,
-                name: "channel-a".to_string(),
-                depth: 0,
-                user_is_admin: true,
-            },
-            ExpectedChannel {
-                id: channel_b_id,
-                name: "channel-b".to_string(),
-                depth: 1,
-                user_is_admin: true,
-            },
-            ExpectedChannel {
-                id: channel_c_id,
-                name: "channel-c".to_string(),
-                depth: 2,
-                user_is_admin: true,
-            },
-            ExpectedChannel {
-                id: channel_c_id,
-                name: "channel-c".to_string(),
-                depth: 1,
-                user_is_admin: true,
-            },
+            (channel_a_a_id, 0),
+            (channel_a_b_id, 1),
+            (channel_b_gamma_id, 1),
+            (channel_a_c_id, 2),
+            (channel_a_d_id, 3),
+            (channel_a_d_id, 2),
         ],
     );
+    // TODO: Make sure to test that non-local root removing problem I was thinking about
 }
 
 #[derive(Debug, PartialEq)]
@@ -1059,3 +1142,20 @@ fn assert_channels(
     });
     pretty_assertions::assert_eq!(actual, expected_channels);
 }
+
+#[track_caller]
+fn assert_channels_list_shape(
+    channel_store: &ModelHandle<ChannelStore>,
+    cx: &TestAppContext,
+    expected_channels: &[(u64, usize)],
+) {
+    cx.foreground().run_until_parked();
+
+    let actual = channel_store.read_with(cx, |store, _| {
+        store
+            .channels()
+            .map(|(depth, channel)| (channel.id, depth))
+            .collect::<Vec<_>>()
+    });
+    pretty_assertions::assert_eq!(actual, expected_channels);
+}

crates/collab/src/tests/test_server.rs

@@ -288,6 +288,7 @@ impl TestServer {
     pub async fn make_channel(
         &self,
         channel: &str,
+        parent: Option<u64>,
         admin: (&TestClient, &mut TestAppContext),
         members: &mut [(&TestClient, &mut TestAppContext)],
     ) -> u64 {
@@ -296,7 +297,7 @@ impl TestServer {
             .app_state
             .channel_store
             .update(admin_cx, |channel_store, cx| {
-                channel_store.create_channel(channel, None, cx)
+                channel_store.create_channel(channel, parent, cx)
             })
             .await
             .unwrap();
@@ -331,6 +332,39 @@ impl TestServer {
         channel_id
     }
 
+    pub async fn make_channel_tree(
+        &self,
+        channels: &[(&str, Option<&str>)],
+        creator: (&TestClient, &mut TestAppContext),
+    ) -> Vec<u64> {
+        let mut observed_channels = HashMap::default();
+        let mut result = Vec::new();
+        for (channel, parent) in channels {
+            let id;
+            if let Some(parent) = parent {
+                if let Some(parent_id) = observed_channels.get(parent) {
+                    id = self
+                        .make_channel(channel, Some(*parent_id), (creator.0, creator.1), &mut [])
+                        .await;
+                } else {
+                    panic!(
+                        "Edge {}->{} referenced before {} was created",
+                        parent, channel, parent
+                    )
+                }
+            } else {
+                id = self
+                    .make_channel(channel, None, (creator.0, creator.1), &mut [])
+                    .await;
+            }
+
+            observed_channels.insert(channel, id);
+            result.push(id);
+        }
+
+        result
+    }
+
     pub async fn create_room(&self, clients: &mut [(&TestClient, &mut TestAppContext)]) {
         self.make_contacts(clients).await;
 
@@ -549,6 +583,41 @@ impl TestClient {
     ) -> WindowHandle<Workspace> {
         cx.add_window(|cx| Workspace::new(0, project.clone(), self.app_state.clone(), cx))
     }
+
+    pub async fn add_admin_to_channel(
+        &self,
+        user: (&TestClient, &mut TestAppContext),
+        channel: u64,
+        cx_self: &mut TestAppContext,
+    ) {
+        let (other_client, other_cx) = user;
+
+        self
+            .app_state
+            .channel_store
+            .update(cx_self, |channel_store, cx| {
+                channel_store.invite_member(
+                    channel,
+                    other_client.user_id().unwrap(),
+                    true,
+                    cx,
+                )
+            })
+            .await
+            .unwrap();
+
+        cx_self.foreground().run_until_parked();
+
+        other_client
+            .app_state
+            .channel_store
+            .update(other_cx, |channels, _| {
+                channels.respond_to_channel_invite(channel, true)
+            })
+            .await
+            .unwrap();
+
+    }
 }
 
 impl Drop for TestClient {