Allow for Instanbul coverage with Playwright

[rokob]

This makes the PlaywrightLauncherPage function similarly to the ChromeLauncher where we attempt to load the coverage from the browser and return that if availble during the stopSession method. Currently the Playwright launcher breaks early if the native instrumentation is not enabled.

We changed to using the Playwright launcher and were suprised that our coverage stopped working even though we are using the babel istanbul plugin which worked when we were using the ChromeLauncher.

See https://github.com/modernweb-dev/web/blob/master/packages/test-runner-chrome/src/ChromeLauncherPage.ts#L93-L132 for the equivalent code.

[changeset-bot]

🦋 Changeset detected

Latest commit: 8484bd3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@web/test-runner-playwright	Patch

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[Westbrook]

Is there testing that can confirm this functionality?

[rokob]

Without this change the newly added test fails with:

  71 passing (47s)
  4 pending
  4 failing

  1) test-runner-playwright chromium
       basic
         coverage
           passes coverage test:
     AssertionError: expected undefined to equal 'something'
      at Context.<anonymous> (/Users/andy.weiss/thirdparty/web/integration/test-runner/tests/basic/runBasicTest.ts:36:43)
      at processImmediate (node:internal/timers:476:21)

  2) test-runner-playwright webkit
       basic
         coverage
           passes coverage test:
     AssertionError: expected undefined to equal 'something'
      at Context.<anonymous> (/Users/andy.weiss/thirdparty/web/integration/test-runner/tests/basic/runBasicTest.ts:36:43)
      at processImmediate (node:internal/timers:476:21)

  3) test-runner-playwright firefox
       basic
         coverage
           passes coverage test:
     AssertionError: expected undefined to equal 'something'
      at Context.<anonymous> (/Users/andy.weiss/thirdparty/web/integration/test-runner/tests/basic/runBasicTest.ts:36:43)
      at processImmediate (node:internal/timers:476:21)

  4) test-runner-playwright all
       basic
         coverage
           passes coverage test:
     AssertionError: expected undefined to equal 'something'
      at Context.<anonymous> (/Users/andy.weiss/thirdparty/web/integration/test-runner/tests/basic/runBasicTest.ts:36:43)
      at processImmediate (node:internal/timers:476:21)

and all tests pass locally for me with this change.

[Westbrook]

Awesome. I’ll take a closer look at these tests and assuming CI is also happy we’ll look to get this merged, soon! 🙇‍♂️