Fix build for React next

[kentcdodds]

Not sure exactly how/when this happened, but the build is failing: https://travis-ci.org/github/testing-library/react-testing-library/builds/703268660

Help welcome!

[MatanBobi]

This looks like a problem with the cleanup in the flushing queued microtasks step in some Node environments..
I've tried to reproduce it on my local env with no luck, I'll try to reproduce it today and then see what's the specific problem.

[nickserv]

Is this an intermittent failure where the first build (before it was rerun with Travis cron) just happened to fail by chance? Or could it be that a dependency updated in a way that changes this behavior?

[marcosvega91]

I don't think is something regarding to a dependency update. As I see from the log, it happens only on some versions of node.

[MatanBobi]

@nickmccurdy
It looks like it started happening quite around the area of pushing the cleanup of queued microstasks and it always fails on the same node version: 12, 14 and current.
It's weird that the initial merge did pass and so did one after that with the same commit as all others who failed..

[MatanBobi]

Just updating that I tried to reproduce this issue with both of the node versions that failed: 12.18.1, 14.4.0 on my local env but all of the tests passed.

[kentcdodds]

The fact that #1171 passed (which introduced the microtask change) is interesting 🤔

[eps1lon]

The tests are failing for react@next and react-dom@next. Make sure you reproduce the CI environment by doing npm install react@next react-dom@next which is executed in these builds (https://travis-ci.org/github/testing-library/react-testing-library/jobs/703268662#L234)

[marcosvega91]

good point, you're right, now the issue is reproducible

[MatanBobi]

The tests are failing for react@next and react-dom@next. Make sure you reproduce the CI environment by doing npm install react@next react-dom@next which is executed in these builds (https://travis-ci.org/github/testing-library/react-testing-library/jobs/703268662#L234)

That's a good point, it also explains why it happens only in CRON since only there we use react@next and react-dom@next. As @marcosvega91 stated, the issue reproduced now.
I'll dig into it today.

[kentcdodds]

Ah yeah, that explains why it's failing for the cron job 😅 Thanks @eps1lon! I forgot we do that.

[nickserv]

Perhaps we should add react@next to the build matrix for all builds rather than just cron builds so we can tell immediately if a new feature is failing on the current next release. Travis also shows multiple jobs in a build side by side, so for example we'd know if a PR failed on @next but not @latest. FWIW I think this would be more similar to Zeit/Vercel Next's usage of GitHub actions for react@next testing.

[kentcdodds]

Nah, I don't want to prevent a release because our tests don't work with an unreleased version of react.

[nickserv]

Good point, we should be able to work around that by adding the @next job as an allowed failure so we can still see the build status without preventing an automated release.

[kentcdodds]

That sounds fine to me