Support Jest's coverage options

I was surprised when I got a warning from npm test stating that Jest’s coverage options aren’t supported. As a prior Jest user I expected them to be supported since Jest’s --coverage option works fine.

While I know I could just change my test script or eject, I think it would reduce confusion to support this out of the box. Is seems like there’s a whitelist for options, how easy would it be to implement support for all the coverage* options?

Output

> react-scripts test --env=jsdom

Out of the box, Create React App only supports overriding these Jest options:

  • collectCoverageFrom
  • coverageReporters
  • coverageThreshold
  • snapshotSerializers.

These options in your package.json Jest configuration are not currently supported by Create React App:

  • collectCoverage
  • coveragePathIgnorePatterns

If you wish to override other Jest options, you need to eject from the default setup. You can do so by running npm ru
n eject but remember that this is a one-way operation. You may also file an issue with Create React App to discuss su
pporting more options out of the box.                                                                               

npm ERR! Test failed.  See above for more details.

[gaearon]

I don’t think you need to put collectCoverage into package.json. Just run npm test -- --coverage as described here to get the coverage report.

I am also not sure why you need coveragePathIgnorePatterns. Isn’t collectCoverageFrom enough to specify where you want it to be collected?

[nickmccurdy]

Whoops, I just double checked and react-scripts test --coverage actually doesn’t run the watcher, it just runs tests once with coverage as if you ran jest --coverage. My mistake, I’m not sure if that functionality is intentional though.