Percy GHA Migration - PR Status check reflects Percy diff state

[jmuzina]

Done

Extension of #5089 that makes the Percy PR status check a bit smarter; now the status check will actually reflect the diff state of the Percy build. If a PR has Percy diffs, it will fail, and it will pass if it has no diffs.

In the case that a PR has diffs that are then approved, you should re-run the snapshots job to update the status check to passed.

Do not review or merge until merging of #5089

Closes WD-11262

QA

• View example PR with Percy diffs
• Verify that the snapshots job fails due to diffs detected
• Follow the Percy build link in the snapshots job above & verify that there are unexpected diffs present.
• Verify that the status check associated with the failing build reports unexpected diffs.
• Verify that the snapshots job run after fixing the above diffs passes with no diffs from baseline
• Verify that the Percy build link associated with the passing snapshot reports no diffs
• Verify that the status check associated with the passing build reports no diffs.

Check if PR is ready for release

If this PR contains Vanilla SCSS code changes, it should contain the following changes to make sure it's ready for the release:

• PR should have one of the following labels to automatically categorise it in release notes:
  • Feature 🎁, Breaking Change 💣, Bug 🐛, Documentation 📝, Maintenance 🔨.
• Vanilla version in package.json should be updated relative to the most recent release, following semver convention:
  • if CSS class names are not changed it can be bugfix relesase (x.x.X)
  • if CSS class names are changed/added/removed it should be minor version (x.X.0)
  • see the wiki for more details
• Any changes to component class names (new patterns, variants, removed or added features) should be listed on the what's new page.

Screenshots

[webteam-app]

Demo

Jenkins

demos.haus

[jmuzina]

Here's a PR in a fork context that demonstrates the above QA: canonical/test-web-percy-gha-migration#13

[bartaz]

We want to try to enable official integration first, instead.

[jmuzina]

Closing this as it will be handled instead by the GHA-Percy integration being worked on by @bartaz