When I run tests on pipe lines occasionally I am getting "Network Error" for different files (because of axios requests). Though some times I don't get errors at all.
But for some reason I can't get that error locally no matter what I do. I use same node version v12.16.1. I have tried to reduce testTimeout to 200 (I got bunch of errors but the were different).
The problem was that one test didn't finished request properly, though test itself finished successfully. As the result next test with request failed. And because of default maxConcurrency: 5 that could be pretty any test.
Though why I was unable to reproduce it locally is still unclear for me.
I was seeing this exact error stack intermittently in a quasi-random subset of tests after upgrading to Apollo Client 3.0. The technique outlined here helped me pinpoint the root cause as an upstream test that was calling an unmocked axios.get():
https://hceris.com/jest-fail-test-if-unexpected-network-request-happens/
