Add comprehensive end-to-end tests for the WebSocket system:
- Protocol tests: auth (valid/invalid token, timeout, double auth),
subscriptions (valid/invalid event, auth required, unsubscribe),
message delivery (notification on team add, doer exclusion,
multi-connection)
- Frontend integration tests: notification badge update, dropdown
rendering, and logout cleanup via browser-level Playwright tests
- Comment notification test: full flow where user B mentions user A
in a task comment and user A receives real-time WebSocket notification
Includes ws test dependency, shared test helper utilities, and
cascade-truncation of notifications when truncating users to prevent
test pollution.
Async event handlers (via Watermill) from the previous test can hold
SQLite connections, starving the next test's fixture setup PATCH request.
Three changes fix this:
1. Track in-flight event handler goroutines with a WaitGroup.
2. Call WaitForPendingHandlers() in the test endpoint before
truncating/inserting data.
3. Navigate the browser to about:blank in fixture teardown to stop
notification polling and other frontend requests between tests.