Try/e2e jest

[scinos]

Changes proposed in this Pull Request

Migrate Calypso e2e tests to Jest.

This is not meant to be merged as is, but an exploration of what we would need to do a full migration and what would be the pros and cons.

Migration:

The migration itself is quite trivial. There are a few changes we have to make to our tests, but mostly can be done by search&replace:

• There is no this.timeout():
  • For tests, we can have an equivalent jest.setTimeout() in the setup files.
  • For hooks, we can pass the timeout as the second parameter.
• before/after hooks should be renamed to beforeAll/afterAll
• Hooks can't have a name

And that's pretty much it. The rest is split files with multiple @parallel suites, set up Jest and configure the build to use Jest instead of Magellan.

Pros:

• Seems to be a bit faster. I got a build in 3m:10s, while trunk is about 3m:30s. This doesn't even use Jest caching, so it may end up running in less than 3 minutes.

• jest-teamcity reporter adds the test filename as part of the test name in TeamCity. This can help identify which tests is failing:
  

• Log are much easier to read, even when running multiple tests in parallel. It is easy to see what was the test suite, what step failed, the error and the stack trace:
  

Cons:

• jest-teamcity reporter adds the test filename as part of the test name... which means that renaming a file will erase the history of the test in TeamCity, as it will appear as a new test.

[github-actions]

Test live: https://calypso.live/?branch=try/e2e-jest

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[scinos]

Implemented in #53702