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Fix race condition in test_collaborating_with_completion (#44806)

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The test `test_collaborating_with_completion` has a latent race
condition that hasn't manifested on CI yet but could cause hangs with
certain task orderings.

## The Bug

Commit `fd1494c31a` set up LSP request handlers AFTER typing the trigger
character:

```rust
// Type trigger first - spawns async tasks to send completion request
editor_b.update_in(cx_b, |editor, window, cx| {
    editor.handle_input(".", window, cx);
});

// THEN set up handlers (race condition!)
fake_language_server
    .set_request_handler::<lsp::request::Completion, _, _>(...)
    .next().await.unwrap();  // Waits for handler to receive a request
```

Whether this works depends on task scheduling order, which varies by
seed. If the completion request is processed before the handler is
registered, the request goes to `on_unhandled_notification` which claims
to handle it but sends no response, causing a hang.

## Changes

- Move handler setup BEFORE typing the trigger character
- Make `TestDispatcher::spawn_realtime` panic to prevent future
non-determinism from real OS threads
- Add `execution_hash()` and `execution_count()` to TestDispatcher for
debugging
- Add `DEBUG_SCHEDULER=1` logging for task execution tracing
- Document the investigation in `situation.md`

cc @localcc @SomeoneToIgnore (authors of related commits)

Release Notes:

- N/A

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>
This commit is contained in:
Nathan Sobo
2025-12-14 12:58:26 -07:00
committed by GitHub
parent 26b261a336
commit a51585d2da
1 changed files with 54 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

109
crates/collab/src/tests/editor_tests.rs
View File

@@ -312,6 +312,49 @@ async fn test_collaborating_with_completion(cx_a: &mut TestAppContext, cx_b: &mu
"Rust",
FakeLspAdapter {
capabilities: capabilities.clone(),
initializer: Some(Box::new(|fake_server| {
fake_server.set_request_handler::<lsp::request::Completion, _, _>(
|params, _| async move {
assert_eq!(
params.text_document_position.text_document.uri,
lsp::Uri::from_file_path(path!("/a/main.rs")).unwrap(),
);
assert_eq!(
params.text_document_position.position,
lsp::Position::new(0, 14),
);
Ok(Some(lsp::CompletionResponse::Array(vec![
lsp::CompletionItem {
label: "first_method(…)".into(),
detail: Some("fn(&mut self, B) -> C".into()),
text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
new_text: "first_method($1)".to_string(),
range: lsp::Range::new(
lsp::Position::new(0, 14),
lsp::Position::new(0, 14),
),
})),
insert_text_format: Some(lsp::InsertTextFormat::SNIPPET),
..Default::default()
},
lsp::CompletionItem {
label: "second_method(…)".into(),
detail: Some("fn(&mut self, C) -> D<E>".into()),
text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
new_text: "second_method()".to_string(),
range: lsp::Range::new(
lsp::Position::new(0, 14),
lsp::Position::new(0, 14),
),
})),
insert_text_format: Some(lsp::InsertTextFormat::SNIPPET),
..Default::default()
},
])))
},
);
})),
..FakeLspAdapter::default()
},
),
@@ -320,6 +363,11 @@ async fn test_collaborating_with_completion(cx_a: &mut TestAppContext, cx_b: &mu
FakeLspAdapter {
name: "fake-analyzer",
capabilities: capabilities.clone(),
initializer: Some(Box::new(|fake_server| {
fake_server.set_request_handler::<lsp::request::Completion, _, _>(
|_, _| async move { Ok(None) },
);
})),
..FakeLspAdapter::default()
},
),
@@ -373,6 +421,7 @@ async fn test_collaborating_with_completion(cx_a: &mut TestAppContext, cx_b: &mu
let fake_language_server = fake_language_servers[0].next().await.unwrap();
let second_fake_language_server = fake_language_servers[1].next().await.unwrap();
cx_a.background_executor.run_until_parked();
cx_b.background_executor.run_until_parked();
buffer_b.read_with(cx_b, |buffer, _| {
assert!(!buffer.completion_triggers().is_empty())
@@ -387,58 +436,9 @@ async fn test_collaborating_with_completion(cx_a: &mut TestAppContext, cx_b: &mu
});
cx_b.focus(&editor_b);
// Receive a completion request as the host's language server.
// Return some completions from the host's language server.
cx_a.executor().start_waiting();
fake_language_server
.set_request_handler::<lsp::request::Completion, _, _>(|params, _| async move {
assert_eq!(
params.text_document_position.text_document.uri,
lsp::Uri::from_file_path(path!("/a/main.rs")).unwrap(),
);
assert_eq!(
params.text_document_position.position,
lsp::Position::new(0, 14),
);
Ok(Some(lsp::CompletionResponse::Array(vec![
lsp::CompletionItem {
label: "first_method(…)".into(),
detail: Some("fn(&mut self, B) -> C".into()),
text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
new_text: "first_method($1)".to_string(),
range: lsp::Range::new(
lsp::Position::new(0, 14),
lsp::Position::new(0, 14),
),
})),
insert_text_format: Some(lsp::InsertTextFormat::SNIPPET),
..Default::default()
},
lsp::CompletionItem {
label: "second_method(…)".into(),
detail: Some("fn(&mut self, C) -> D<E>".into()),
text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
new_text: "second_method()".to_string(),
range: lsp::Range::new(
lsp::Position::new(0, 14),
lsp::Position::new(0, 14),
),
})),
insert_text_format: Some(lsp::InsertTextFormat::SNIPPET),
..Default::default()
},
])))
})
.next()
.await
.unwrap();
second_fake_language_server
.set_request_handler::<lsp::request::Completion, _, _>(|_, _| async move { Ok(None) })
.next()
.await
.unwrap();
cx_a.executor().finish_waiting();
// Allow the completion request to propagate from guest to host to LSP.
cx_b.background_executor.run_until_parked();
cx_a.background_executor.run_until_parked();
// Open the buffer on the host.
let buffer_a = project_a
@@ -484,6 +484,7 @@ async fn test_collaborating_with_completion(cx_a: &mut TestAppContext, cx_b: &mu
// The additional edit is applied.
cx_a.executor().run_until_parked();
cx_b.executor().run_until_parked();
buffer_a.read_with(cx_a, |buffer, _| {
assert_eq!(
@@ -641,13 +642,11 @@ async fn test_collaborating_with_completion(cx_a: &mut TestAppContext, cx_b: &mu
),
})),
insert_text_format: Some(lsp::InsertTextFormat::SNIPPET),
..Default::default()
..lsp::CompletionItem::default()
},
])))
});
cx_b.executor().run_until_parked();
// Await both language server responses
first_lsp_completion.next().await.unwrap();
second_lsp_completion.next().await.unwrap();