Some async tests are missing `asyncStart`/`asyncEnd`

[osa1]

While debugging dart-lang/sdk#54140 @mkustermann realized that some of the async tests in co19 are missing asyncStart and asyncEnd:

• https://github.com/dart-lang/co19/blob/master/Language/Functions/element_type_A02_t03.dart
• https://github.com/dart-lang/co19/blob/master/Language/Functions/element_type_A02_t04.dart
• https://github.com/dart-lang/co19/blob/master/Language/Functions/element_type_A02_t06.dart

When testing in the browser, without asyncStart and asyncEnd, the test driver is not waiting for the test to finish and declaring a success even when the test actually fails.

I quickly searched for all the files with an async main and an asyncStart, and when I compared the outputs I see that there are dozens of files where main is async but the file doesn't have asyncStart. For example:

• LanguageFeatures/Control-flow-collections/dynamic_semantics_list_A03_t02.dart
• Language/Statements/For/Asynchronous_For_in/execution_A02_t01.dart

I used ag -Q 'main() async' -c to find tests with async main and ag -Q 'asyncStart' -c to find the tests with asyncStart. (I think it might make sense to search for await instead of main() async).

[sgrekhov]

@osa1 thank you! I added some missed asyncStart/End(). It's not supposed that all async test should have asyncStart/End(). Tests like

main() async {
  await test1();
  ...
  await test2();
}

don't need asyncStart/End(). But I found a lot of tests that have excessive async.

[nshahan]

@sgrekhov
I've noticed that these tests are flaky for dart2js and DDC when running on Firefox and Safari even though they all use the TouchEvent constructor which is not present in those browsers.

LibTest/html/Element/onTouchCancel_A01_t01
LibTest/html/Element/onTouchEnd_A01_t01
LibTest/html/Element/onTouchEnter_A01_t01
LibTest/html/Element/onTouchLeave_A01_t01
LibTest/html/Element/onTouchMove_A01_t01
LibTest/html/Element/onTouchStart_A01_t01
LibTest/html/Element/touchCancelEvent_A01_t01
LibTest/html/Element/touchEndEvent_A01_t01
LibTest/html/Element/touchEnterEvent_A01_t01
LibTest/html/Element/touchLeaveEvent_A01_t01
LibTest/html/Element/touchMoveEvent_A01_t01
LibTest/html/Element/touchStartEvent_A01_t01
LibTest/html/IFrameElement/onTouchCancel_A01_t01
LibTest/html/IFrameElement/onTouchEnd_A01_t01
LibTest/html/IFrameElement/onTouchEnter_A01_t01
LibTest/html/IFrameElement/onTouchLeave_A01_t01
LibTest/html/IFrameElement/onTouchMove_A01_t01
LibTest/html/IFrameElement/onTouchStart_A01_t01

They should consistently fail but the fact that they can sometimes pass leads me to believe that they might complete without running the code or recognizing the failure. It makes me question the reliability of the asyncStart/End guards. Can you think of other explanations?

Since the API simply doesn't exist I'm going to start skipping these tests on those browsers but I wanted to call out this observation.

[sgrekhov]

@nshahan where do you see these flaky results? According to the https://dart-current-results.web.app/#/filter=co19/LibTest/html/Element/,co19/LibTest/html/IFrameElement/ all of these tests are not flaky but fail with TouchEvent is not defined error.
May be it makes sense to change the expected result in this case? If we have no event to test then test should succeed. It's not an error if we have nothing to test. I'm going to update the tests this way.