test(node): Fix flaky ANR tests by waiting for debugger to be ready#21011
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The ANR worker thread creates an InspectorSession and connects to the main thread's debugger. Previously, tests would start blocking work immediately, but the debugger session might not be fully initialized yet, causing stack traces to capture the wrong location (processTimers instead of longWork). This adds a waitForDebuggerReady helper to @sentry-internal/test-utils that polls inspector.url() to detect when the debugger is active, then waits 200ms for the async session setup to complete before starting the blocking work. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
nicohrubec
approved these changes
May 19, 2026
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did you verify that you could actually reproduce the flakiness locally without this change? |
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Yes it failed sometimes locally without the fix. I ran 1000 tests after each other to verify that. My laptop is close to fried |
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lol lgtm then |
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closes #20704
closes JS-2372
closes #20959
closes JS-2524
The ANR worker thread creates an InspectorSession and connects to the main thread's debugger. Previously, tests would start blocking work immediately, but the debugger session might not be fully initialized yet, causing stack traces to capture the wrong location (processTimers instead of longWork).
This adds a
waitForDebuggerReadyhelper to the test utils that pollsinspector.url()to detect when the debugger is active, then waits 200ms for the async session setup to complete before starting the blocking work.First the LLM suggested to increase the timeout, but I didn't think that was a good solution, given that CI good have worse when it's busy. I tested that locally a lot of times and tried to slow down the process, seemed stable so far.