For some reason I had a test who suddenly failed, mix test test/pleroma/web/o_auth/app_test.exs:54. A user has a list of applications and this test adds them and then sees if the list it gets back is the same as the apps it added.
When I ran mix test a day before I didn't have this problem and when I pushed code today in a different MR, the pipeline succeeded (see https://git.pleroma.social/ilja/pleroma/-/jobs/205827), yet locally it failed. So it seems the test can sometimes succeed and sometimes fail, which makes it untrustworthy.
The failure I see is because the returned list is in reverse order. I assume that's not per sé wrong. You just want to know if the apps you added are actually there. I fixed the test by first ordering the lists before comparing.
AFAICT (and as far as that's relevant) the test got introduced in commit cb2a072e62
8b843be03e