Windows web_tool_tests_1_2 is 2.13% flaky

[fluttergithubbot]

The post-submit test builder Windows web_tool_tests_1_2 had a flaky ratio 2.13% for the past (up to) 100 commits, which is above our 2.00% threshold.

One recent flaky example for a same commit: https://ci.chromium.org/ui/p/flutter/builders/prod/Windows%20web_tool_tests_1_2/2582
Commit: 6af58c7

Flaky builds:
https://ci.chromium.org/ui/p/flutter/builders/prod/Windows%20web_tool_tests_1_2/2582
https://ci.chromium.org/ui/p/flutter/builders/prod/Windows%20web_tool_tests_1_2/2573
https://ci.chromium.org/ui/p/flutter/builders/prod/Windows%20web_tool_tests_1_2/2571

Recent test runs:
https://flutter-dashboard.appspot.com/#/build?taskFilter=Windows%20web_tool_tests_1_2

Please follow https://github.com/flutter/flutter/wiki/Reducing-Test-Flakiness#fixing-flaky-tests to fix the flakiness and enable the test back after validating the fix (internal dashboard to validate: go/flutter_test_flakiness).

[zanderso]

Successful runs can be up in the 27 - 29 minute range, so either the 30 minute timeout needs to be increased, or the tests need to be further sharded. Routing to platform-web to further triage.

[yjbanov]

It looks like a hard error that manifests as a timeout. The errors in the logs are about locked files on Windows that cannot be deleted:

00:03 +18: C:/b/s/w/ir/x/w/flutter/packages/flutter_tools/test/web.shard/debugger_stepping_web_test.dart: Web debugger can step over statements
Failed to delete C:\b\s\w\ir\x\t\flutter_debugger_stepping_test.dea98973: PathAccessException: Deletion failed, path = 'C:\b\s\w\ir\x\t\flutter_debugger_stepping_test.dea98973' (OS Error: The process cannot access the file because it is being used by another process.
, errno = 32)
00:57 +19: C:/b/s/w/ir/x/w/flutter/packages/flutter_tools/test/web.shard/expression_evaluation_web_test.dart: Flutter test for web can evaluate complex expressions in library without pause
Failed to delete C:\b\s\w\ir\x\t\flutter_run_expression_eval_test.b3a7a15a: PathAccessException: Deletion failed, path = 'C:\b\s\w\ir\x\t\flutter_run_expression_eval_test.b3a7a15a' (OS Error: The process cannot access the file because it is being used by another process.
, errno = 32)

I'm assuming after this error the tool gets stuck, eventually leading to the timeout.

[annagrin]

I think the tests got too big and are hitting some per-file limit. I'll send a PR splitting the file.

[fluttergithubbot]

[prod pool] current flaky ratio for the past (up to) 100 commits is 0.00%. Flaky number: 0; total number: 99.

[Hixie]

We usually just try/catch around win32 deletion issues, so if that is what's causing it the fix for that is probably the same.

[annagrin]

The error messages come from tests added in #122776 and reverted in #122855. The original flakes are fixed in a package:vm_service update, so I am closing this as fixed.