feat(core): Move zoneless change detection to dev preview

[atscott]

This commit moves zoneless from experimental to developer preview.

• Update tag on provider API
• Remove "experimental" from provider name
• Move documentation from "experimental features" to "Best practices -> Performance" (at least temporarily until there is a better place)

Blocked by the following:

• fix(@angular/ssr): manage unhandled errors in zoneless applications angular-cli#28405 / Vite dev server crashes when HttpClient receives non-200 code #58123
• fix(core): Flush animations when no component has been checked by CD #58089
• How to capture errors outside Angular context in zoneless? #56240
  • feat(core): Add provider which reports unhandled errors on window t… #60704
  • (soft blocker - just ensure it does happen) feat(@schematics/angular): Add global error listeners to new app generation angular-cli#30053
  • Docs updates (docs: Add error handling documentation #60848)

Follow up work:

• Remove "experimental" from zoneless and add prompt for new apps angular-cli#30034
• Remove re-export of the provider once g3 cleanup to the new name is finished

[github-actions]

Deployed adev-preview for e546e31 to: https://ng-dev-previews-fw--pr-angular-angular-60748-adev-prev-d65gzfow.web.app

Note: As new commits are pushed to this pull request, this link is updated after the preview is rebuilt.

[rainerhahnekamp]

Great to see that zoneless is moving to developer preview!

What I’m still missing, though, is communication around testing. A lot of existing tests rely on fakeAsync or waitForAsync, which don’t work without zone.js. This raises important questions: Is there a migration path? What’s the recommended approach to handle async behavior in tests going forward?

If fakeAsync/waitForAsync are no longer supported, this could mean a substantial rewrite of many tests. I’d even argue that switching an application to zoneless is relatively straightforward — but updating the tests might be significantly more challenging.

If there’s already an issue or discussion covering this topic, it would be great to link it here. Otherwise, happy to open one if that helps.

[atscott]

You do not have to remove fakeAsync from your tests unless you want to purge the ZoneJs library entirely. It’s not much different from any other mock clock library. You could migrate to a different mock clock implementation like sinonJS or jasmine clock if you want.

[rainerhahnekamp]

Thanks, I understand. Still, I wonder - if I choose to go zoneless in my app, wouldn’t it feel natural to do the same in my tests?

It might be helpful to include a note in the docs explaining:

1. That waitForAsync and fakeAsync rely on zone.js and keeping them for tests is an option.
2. A few example tests that show common async scenarios without zone.js and how to leverage the existing async utilities of Jasmine & Jest.

Would that be something worth adding? I’d be more than happy to help out with a PR if that’s helpful!

[atscott]

Yes, absolutely. The testing documentation in general could use a good refresh and these would be good topics to cover. Some of them are already in the component testing scenarios page, though that page should be reviewed and updated as a whole.

[rainerhahnekamp]

Yes, absolutely

Very good. Then I have something to do :)

[kirjs]

Reviewed-for: public-api

[AndrewKushnir]

Reviewed-for: public-api

[alxhub]

Reviewed-for: global-approvers

[pkozlowski-opensource]

This PR was merged into the repository by commit 953c4b2.

The changes were merged into the following branches: main