Testing: Not possible to set collectCoverageFrom (and possibly other options)

[charlieTheBotDev]

Stencil version:

 @stencil/core@1.16.0

I'm submitting a:

[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://stencil-worldwide.herokuapp.com/ or https://forum.ionicframework.com/

Current behavior:

Setting testing.collectCoverageFrom is not passed to Jest.

Expected behavior:

It should pass it through

Steps to reproduce:

Add collectCoverageFrom with a value (i.e. with a single file, or a set with negation) and set collectCoverage to true. The coverage generated will not match the expectation passed in.

Related code:
https://github.com/ionic-team/stencil/blob/master/src/testing/jest/jest-config.ts#L39
https://github.com/ionic-team/stencil/blob/master/src/testing/jest/jest-config.ts#L45-L49

Other information:

https://github.com/ionic-team/stencil/blob/master/src/testing/jest/jest-config.ts#L39

There is no default defined for this option (see collectCoverageFrom docs and, being undefined means that it is not looped over in the function here:
https://github.com/ionic-team/stencil/blob/master/src/testing/jest/jest-config.ts#L45-L49

It's also worth noting that collectCoverageFrom is potentially not the only option affected by this as anything set to undefined in the defaults will not be set (unless set in the subsequent block of if statements)

I'll raise a PR for this if I get a chance

Workaround
Assume that all files loaded by Jest will be covered and use coveragePathIgnorePatterns to negate anything you don't want.

If a file is not covered in your output, it means you have not loaded it in any of your tests.

Note: Puppeteer doesn't contribute to coverage so don't expect e2e tests to add to coverage 😉

[irega]

We need this for our project too. Created PR for it #2613