test(picker-internal): screenshot and a11y (axe)

[sean-perkins]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed
• Lint (npm run lint) has passed locally and any fixes were made for failures

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe): Test migration

What is the current behavior?

ion-picker-internal e2e tests are written with puppeteer.

What is the new behavior?

• Added @axe-core/playwright for a11y testing
• Screenshot tests for ion-picker-internal usages

Does this introduce a breaking change?

• Yes
• No

Other information

Opted for testing AXE violations with:

expect(results.violations).toEqual([]);

instead of:

expect(results.violations.length).toEqual(0);

so that violations are printed in CI in the output log, instead of "expected 0, returned 1".

[liamdebeasi]

A couple screenshots do not appear to be correct:

1. core/src/components/picker-internal/test/basic/picker-internal.e2e.ts-snapshots/picker-internal-popover-diff-ios-ltr-webkit-linux.png shows the popover + backdrop, but the selected items are incorrect. (the RTL version is correct. Maybe this test is flaky?)
2. core/src/components/picker-internal/test/basic/picker-internal.e2e.ts-snapshots/picker-internal-popover-diff-md-ltr-webkit-linux.png shows the backdrop but no popver.

[sean-perkins]

Waiting for the present event to be emitted seems to have more consistent results.

Still need to dig into this one on my end:

• https://github.com/ionic-team/ionic-framework/blob/2e6697b00c6a14f3fafba19d2e95fd2b82947830/core/src/components/picker-internal/test/basic/picker-internal.e2e.ts-snapshots/picker-internal-modal-diff-ios-ltr-Mobile-Safari-linux.png

Not setting the selected value is likely a rendering issue that a higher timeout may resolve, but will see if there's other alternatives first.

[averyjohnston]

This LGTM other than the two screenshots Liam mentioned.