ESLint checks (and the upcoming Flow integration) is missing in tests

Followup to this comment thread: https://github.com/facebookincubator/create-react-app/pull/1152#discussion_r90960900

Description

When running the start or test lint issues or flow issues (with #1152) are not reported if they are not within a test file (not required by webpack, only seen by jest).

Expected behavior

I see three acceptable UX here:

1. The start script should explore test files as well and run the eslint loader (+ flow plugin) on it
2. The test script should run eslint (+ flow) each time jest triggers a change from its watch
3. Add an independent script that will watch all files at the same time

The first one would be the best, the last one would be ok, but let’s try to avoid it!

Actual behavior

Test files are completely ignored by static checks.

Environment

Run these commands in the project folder and fill in their results:

1. npm ls react-scripts (if you haven’t ejected): 0.8.1
2. node -v: 6.7.0
3. npm -v: 3.10.3
4. yarn --version: 0.18.0

Then, specify:

1. Operating system: macOS Sierra 10.12.2 Beta (16C41b)
2. Browser and version: Google Chrome 54.0.2840.98 (64-bit)

Reproducible Demo

https://github.com/rricard/cra-failing-test-checks

[gaearon]

This is interesting: https://github.com/rogeliog/jest-runner-eslint

[gaearon]

Meh. It doesn’t seem that important, and above all test runs must be fast. Happy to look at PRs implementing this but we won’t be doing it ourselves.