Skip to content

Fix flaky FileWatcherTests.DeleteSubfolder test #54801

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
MichaelSimons wants to merge 4 commits into from
Closed

Fix flaky FileWatcherTests.DeleteSubfolder test #54801

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
5ff8316
Fix flaky DeleteSubfolder test by waiting for expected events
MichaelSimons Jun 16, 2026
c6054d1
Sort missing changes for deterministic failure messages
MichaelSimons Jun 16, 2026
c2c2015
Potential fix for pull request finding
MichaelSimons Jun 16, 2026
cb5b765
Merge branch 'main' into michaelsimons/fix-flaky-delete-subfolder-test
MichaelSimons Jun 17, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 8 additions & 3 deletions test/dotnet-watch.Tests/FileWatcher/FileWatcherTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -40,21 +40,23 @@ private async Task TestOperation(
}

var operationCompletionSource = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
var expectedSet = new HashSet<ChangedPath>(expectedChanges);
Assert.True(expectedSet.Count == expectedChanges.Length, "expectedChanges must not contain duplicates.");
var filesChanged = new HashSet<ChangedPath>();
Comment thread
Copilot marked this conversation as resolved.

EventHandler<ChangedPath> handler = null;
handler = (_, f) =>
{
if (filesChanged.Add(f))
{
output.WriteLine($"Observed new {f.Kind}: '{f.Path}' ({filesChanged.Count} out of {expectedChanges.Length})");
output.WriteLine($"Observed new {f.Kind}: '{f.Path}' ({filesChanged.Count} changes, {expectedSet.Count(e => filesChanged.Contains(e))} out of {expectedChanges.Length} expected)");
}
else
{
output.WriteLine($"Already seen {f.Kind}: '{f.Path}'");
}

if (filesChanged.Count == expectedChanges.Length)
if (expectedSet.IsSubsetOf(filesChanged))
{
watcher.EnableRaisingEvents = false;
watcher.OnFileChange -= handler;
Expand All @@ -78,7 +80,10 @@ private async Task TestOperation(
var task = operationCompletionSource.Task;
await (Debugger.IsAttached ? task : task.TimeoutAfter(DefaultTimeout));

AssertEx.SequenceEqual(expectedChanges, filesChanged.OrderBy(x => x.Path));
// Verify all expected changes were observed (extra events from the OS are acceptable)

@tmat tmat Jun 17, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Actually, extra events can cause different watch behavior, so they are generally not acceptable.

Are the events non-deterministic on Linux?

@tmat tmat Jun 17, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We can modify the logic so that a test can list specific optional events that may occur.

var missing = expectedSet.Except(filesChanged).OrderBy(x => x.Path).ToArray();
Assert.True(missing.Length == 0,
$"Expected changes not observed: {string.Join(", ", missing.Select(m => $"{m.Kind}: '{m.Path}'"))}\nActual changes: {string.Join(", ", filesChanged.OrderBy(x => x.Path).Select(m => $"{m.Kind}: '{m.Path}'"))}");
Comment thread
MichaelSimons marked this conversation as resolved.
}

private sealed class TestFileWatcher(ILogger logger)
Expand Down
Loading