npm test fails if the project doesn't have git

Apparently Jest did this. Oops!

Determining test suites to run...
--watch is not supported without git/hg, please use --watchAll 
npm ERR! Test failed.  See above for more details.

[SimenB]

Note that, unless somebody (probably meaning @mjesun) wants to do some cherry-picking, the next release of Jest will be a major, so any change we make to Jest will most likely not be something CRA can pick up before its next major. So a workaround in CRA makes sense regardless

[rogeliog]

I agree. From what I’ve been looking at, it seems to be that there was a regression introduced between jest@20.x which is what create-react-app@1.15 uses and jest@22.0.0. This was fixed by providing a better message for the exception, but still exiting with non-zero.

I’m sure @cpojer might provide better insights, but here are my initial thoughts.

1. Change the behavior in Jest to gracefully handle --watch in non-VCS environments. (Which is how it used to behave.) Probably by just falling back to --watchAll.
2. Patch CRA to allow --watch to behave as expected.
3. Release this change in the next Jest release.
4. Remove the patch in CRA and upgrade Jest