React-native: Make master to pass tests on CI

[grabbou]

Currently CI is broken due to flow failing. After investigating that matter for a bit, it turns out issues are coming from metro-bundler package.

It doesn't happen on 0.49-stable and has been a result of either flow or metro-bundler being updated.

I am opening this issue to keep a better track of the status of this issue. Further more, I would also suggest to change the order of tests being run on the CI. I believe flow and eslint should run last, after unit tests. They often break or error temporarily and I've seen many PRs landing to the repo that break those two test suites. That, unfortunately, makes unit tests to never run and I am afraid some might ignore them for time being.

For reference: This issue is currently blocking release of 0.50-stable branch.

CC: @cpojer @hramos

[fernandopasik]

metro-bundler is using an old version of flow.

[fernandopasik]

Ok, it was updated but after the last release.

They still haven't updated the package.json flow dependency though

[grabbou]

Good catch! I thought it got included in the last release. I have asked for updated release already and waiting for the update.

[grabbou]

Okay, I've figured out where the issue was. I left details on the problem on metro-bundler repo here.

I am fixing the 0.50-stable branch as answered in that comment and should hit npm in a second.

There are two things that one has to do in order to fix master:

• update metro to v0.20.0 (released today, there's already open issue about keeping these two in sync)
• perform steps as advised in the diff linked above

[grabbou]

Unfortunately, mockFS is broken on Node lower than 8 which breaks our tests. Unfortunately, I left the office. Will keep working on that issue tomorrow.

[grabbou]

Pull requests #16301, #16302, #16303, #16308 fix all failures and make master green again. As a proof, 0.50-stable is green and about to hit npm soon.

[grabbou]

Tests are green now, except failing Travis, but that wasn't in scope for this issue. I am going to work on migrating Travis to make CI green.