Fix flaky @babel/cli test

[JLHwung]

Q	A
Fixed Issues?	The @babel/cli watch test is flaky because lack of inter-process communication
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

To re-run the @babel/cli test again and again, I have pushed some CI maintenance commits.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/51553/

[nicolo-ribaudo]

I love this PR

[nicolo-ribaudo]

This might still not solve it because it just "waits more", but 2s should be more then enough 👍

[nicolo-ribaudo]

We do we always run it now?

[JLHwung]

Good catch. I should have left a comment here. This step was previously in the prepare-yarn-cache job including the step yarn-cache. Not long ago it was extracted to a separate job yarn-validate which can't access the yarn-cache output anymore, so the condition here is always true now. The dedupe check is around 2 seconds so we can just leave it here.

[nicolo-ribaudo]

I'm merging this with a single review because it doesn't affect any source code, and it fixes a super annoying problem that makes ~30% of CI runs fail.

[liuxingbaoyu]

There seems to be a failure for the same reason.

We can consider adding a watch ready output.

Or consider the following changes:

  await new Promise(resolve => setTimeout(resolve, 2000));
  fs.writeFileSync("./file.txt", "Updated!");

 let i = 0;
  setInterval(() => {
    fs.writeFileSync("./file.txt", `Updated${i++}!`);
  }, 300);