Investigate test failures on Windows after Dart 2.17.0 release

[elliette]

There are a couple tests that have been consistently flaky since updating the min constraint to Dart 2.17.0

#1612 is a draft PR to try to fix the flakes, skipping them for Windows. It looks like the debug connection is being shut down on Windows only.

[elliette]

This is only occurring on Windows. It is possible that web debugging on Windows is currently broken.

[annagrin]

I keep encountering the following flakes:

• devtools_tests.dart

I was running some tests on windows and saw those failures as well. The devtools_tests failures seem to be due to a race - we are waiting for couple of seconds after pressing Alt-D and before checking for existence of the devtools window, but it seems this is not always enough time. We might need a more reliable way of detecting when devtools window have started - one way could be by listening to dwds.events and waiting for DebuggerReady event .

webdev/dwds/test/devtools_test.dart

Line 39 in c1d2237

await Future.delayed(const Duration(seconds: 2));

• events_tests.dart

I have not seen those while running tests on my windows laptop, but have encountered the flake in CI.
Those just seem to time out on windows. They also include launching devtools but actually checking for arrival of the event. I am trying to add more time for them in my latest PR: #1615

• chrome_proxy_service_test.dart:

I only have seen this in CI, seems like it might be a race condition. This test used to be disabled on windows for being flaky, and enabled after a few race condition fixes. Looks like the flakiness has returned.

shared context getStack throws if not paused (failed)

Retry: shared context getStack throws if not paused
  Retry: shared context getStack throws if not paused
  Retry: shared context getStack throws if not paused
  Expected: throws <Instance of 'RPCError'>
    Actual: <Instance of 'Future<Stack>'>
     Which: emitted Stack:<[Stack frames: [[Frame index: 0]], messages: [], truncated: false]>