test(playwright): add tests for editor theme selection logic

[huyenltnguyen]

Checklist:

• I have read and followed the contribution guidelines.
• I have read and followed the how to open a pull request guide.
• My pull request targets the main branch of freeCodeCamp.
• I have tested these changes either locally on my machine, or GitPod.

This PR:

• Adds tests for the theme selection logic in the code editor
• Closes Create a test to make sure that editor theme is in sync with the app theme #49784

Note: While the theme selection logic is fairly simple, the implementation involves window.matchMedia(), which is an API that JSDOM doesn't support. It will require heavily mocking the matchMedia API if we write unit tests, while it's much simpler with e2e as Playwright supports this feature out of the box (https://playwright.dev/docs/api/class-testoptions#test-options-color-scheme).

[huyenltnguyen]

Ugh. Yet another Webkit test that only fails in CI but not local.

[huyenltnguyen]

We do have storageState set during the setup phase:

freeCodeCamp/e2e/global-setup.ts

Line 8 in 84a81c8

.storageState({ path: 'playwright/.auth/certified-user.json' });

But for some reason that doesn't have any effect, and the user is logged out, which causes some tests to fail. Setting storageState again within the test suite is the only workaround at the moment, until I can figure out what the issue is.

[ojeytonwilliams]

I was confused by this too. It turns out we do setup storageState, but we we don't use it by default. So, any tests that require a signed-in user have to manually specify test.use, like you did here.

Do you think it would be more intuitive to default to using it? I'm leaning towards "yes".

[huyenltnguyen]

Oh, I see.

Yes, I think it makes sense to make this the default (I guess that's the purpose of the global login step, so that we don't have to log in manually).

[huyenltnguyen]

This isn't related to the PR changes, but it's weird that the Python tests failed locally for me, but passed in CI. Those tests failed on my local main, too.