Jest: Only get coverage for files that have been imported in tests

[mattotodd]

When using collectCoverage, I only get coverage for files that are imported and tested (and not mocked). And it works fine for those files, but if I then add a new file to my project, and do not write any tests for it, it does not show up as not covered. The coverage results make it look like you have a lot higher coverage than you really do.

Is there any way to force it to include coverage for all js files within my source? So that if someone adds a new file, the coverage results will include that file as uncovered in the results?

[browniefed]

I never found a way, ended up writing a script that runs through and does a require of every file in our app directory.

[dinodsaurus]

Im having the same problem, and I dont think that collectCoverageOnlyFrom is a good solution :)

[samgqroberts]

+1
I'm about to do @browniefed 's plan but it's a bit of a sigh that it's necessary

[cpojer]

I'd be open to accepting a pull request if someone finds a sane way to do this. I expect it to be pretty slow though if you run this as a separate step. I guess what you are looking for here is do what @browniefed suggested - write a test that requires an entire app. Since you need basic instrumentation I don't think there will be any good generic way to do this other than writing a test itself.

Feel free to reopen if you want to submit a pull request but I'm probably not going to have time to build this anytime soon myself.

[rafaelmaiolla]

+1

[kentcdodds]

I feel like I heard recently that this was actually implemented somehow, is that the case? Or is there any existing module that makes this easier than just doing a glob + require myself?

[kentcdodds]

Alrighty, for posterity, here's what I have. I hope it's helpful:

/**
 * Without this file, files that have no tests
 * aren't included in test coverage metrics.
 * This file remedies that and ensures that untested
 * files are counted against us in the coverage metrics.
 * This helps keep us get a true picture of the overall
 * code coverage of the project.
 */
import { resolve } from 'path'
import glob from 'glob'

test('dynamically require project files', () => {
  const globToCover = resolve(__dirname, './**/!(*.test).js')
  const filesToCover = glob.sync(globToCover)

  // if we don't have any filesToCover, then something's probably wrong...
  expect(filesToCover.length > 0, `there should be at least a handful of files in our codebase`)

  // if we have too many files to cover then something's probably wrong too...
  expect(filesToCover.length < 25, `there shouldn't be this many files in our codebase`)

  // dynamically require files
  filesToCover.forEach((file) => {
    try {
      require(file)
    } catch (error) {
      // ignore the error.
      // our purposes of getting the file
      // insturmented for coverage have been accomplished
      // by simply requiring the file.
    }
  })
})

[cpojer]

collectCoverageFrom can be used for this, it takes globs to match files and then runs coverage on all files in the project that match.

[kentcdodds]

Wonderful! That totally works. So much better. Thanks!