Retry on transient Skia failure.

[Hixie]

This works around https://g-issues.skia.org/issues/40044713 using exponential backoff.

This is completely untested because I have no idea how to test it.

Also I only changed one of the code paths here. I figure if we get success here then we can start propagating the change to other places in this file that generate errors, maybe factoring out the retry and error reporting logic so it's not duplicated multiple times.

[flutter-dashboard]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie or stuartmorgan on the #hackers channel in Chat (don't just cc them here, they won't see it! Use Discord!).

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

[Hixie]

I added a test. It uses zones. I don't know how else to test this.

[Piinks]

Couple of nits, but LGTM regardless!

[Piinks]

I do not recall why, but all the tests for the client are with the rest of the flutter_goldens tests. There is already a FakeProcessManager etc. there if you want to move them there to share code.

Then again, it does make more sense to test the client.. in the client package. 🙃

[Hixie]

Weird. Why are they two packages then? Should we merge them? There's no README for either so I'm not sure I really understand the intended use of these packages...

[Hixie]

I think I'm going to land this as-is for now and we can talk about what we want to do with these packages separately. Either way we're going to have to follow-up here (either this helps the flakiness or not, and if it does, we'll want to more aggressively do this approach in other places in this file).

[Piinks]

This is nifty. :)

[Hixie]

It's horrific is what it is but there we are. :-)

[Piinks]

Holy dependencies batman!

[Hixie]

Yeah.

[Piinks]

Maybe at this point we should add avoid_print for the whole file

[Hixie]

I'm trying to increase the pain I feel each time I add one so that eventually I snap and fix the tech debt...

[Hixie]

00:09 +6 -1: SkiaGoldClient throws for error state from tryjobAdd [E]                                                                                                                                  
  Expected: throws <Instance of 'SkiaException'> with `message`: contains 'result-state.json'
    Actual: <Instance of 'Future<void>'>
     Which: threw SkiaException:<SkiaException: Golden test for "golden_file_test" failed with exit code 1 for a reason unrelated to pixel comparison.
                  
                  stdout from gold:
                    Fallback failure
                  
                  stderr from gold:
                    Fallback failure
                  >
            stack package:flutter_goldens_client/skia_client.dart 394:7  SkiaGoldClient.tryjobAdd
                  ===== asynchronous gap ===========================
                  package:matcher                                        expect
                  package:flutter_test/src/widget_tester.dart 458:18     expect
                  test/flutter_goldens_test.dart 569:7                   main.<fn>.<fn>
                  
            which has `message` with value 'Golden test for "golden_file_test" failed with exit code 1 for a reason unrelated to pixel comparison.\n'
                    '\n'
                    'stdout from gold:\n'
                    '  Fallback failure\n'
                    '\n'
                    'stderr from gold:\n'
                    '  Fallback failure\n'
                    '' which does not contain 'result-state.json'
  
  package:matcher                                     expect
  package:flutter_test/src/widget_tester.dart 458:18  expect
  test/flutter_goldens_test.dart 569:7                main.<fn>.<fn>
  

To run this test again: /b/s/w/ir/x/w/flutter/bin/cache/dart-sdk/bin/dart test /b/s/w/ir/x/w/flutter/packages/flutter_goldens/test/flutter_goldens_test.dart -p vm --plain-name 'SkiaGoldClient throws for error state from tryjobAdd'