Jest: coverage summary does not show data for 24.0.0

[SamMaxwell]

🐛 Bug Report

after upgrading to jest 24.0.0 and running "npm test" on my moderate-sized projects no longer show file-level metrics in the coverage summary and the "All Files" aggregates are all 0 (% Stmts, % Branch, % Funcs, %Lines), even though the tests cover the files at 100% for all files. if I simply downgrade to jest 23.6.0 (and change nothing else) then the coverage details show up.

To Reproduce

git clone https://github.com/SamMaxwell/jest-issue-7734.git
npm i
npm test
_notice that the coverage summary is wrong_
npm uninstall jest
npm i [email protected] --save-dev
npm test
_notice that the coverage summary shows the correct metrics_

Link to repo

git clone https://github.com/SamMaxwell/jest-issue-7734.git

Expected behavior

The console output has a coverage summary that includes file test coverage data and "All Files" aggregates that aren't all 0

[thymikee]

Would you mind setting a repro we can test?

[SamMaxwell]

https://github.com/SamMaxwell/jest-issue-7734.git

[SamMaxwell]

npm i (to get jest 24.0.0)
npm test (see that the coverage metrics are all 0)
npm uninstall jest
npm i [email protected] --save-dev
npm test (see that the coverage metrics are all 100)

[SamMaxwell]

I think 24.0.0 messed up coverage in general. I even commented out some tests to see if it would report the uncovered lines and it still did not report anything. (but works as expected in 23.6.0)

[grosto]

The problem is with collectCoverageFrom.
Jest uses library micromatch for glob matching. It got updated(https://github.com/facebook/jest/pull/6650) to a new version in Jest 24. This new version does not match with .js files with the pattern from your config('**/*.{js}').

I have reproduced this in the repl below:
https://repl.it/repls/BlankNotableAbility

If you change the pattern to '**/*.js' or '**/*.{js,}', it will work.

[thymikee]

Thanks @grosto for checking that out. Yup we've upgraded micromatch to v3, so make sure your globs are valid.

[SamMaxwell]

Thanks @grosto and @thymikee, the new globs made it work as expected