test coverage is empty - v3.0.0

[pete-redmond-cko]

Is this a bug report?

yes, test coverage is always empty

After updating react-scripts to 3.0.0 test coverage is always empty, this worked before in v2.1.8

---

v2.1.8

v3.0.0

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Did you try recovering your dependencies?

This happens after booting an app up using create react app using typescript create-react-app cra-coverage-example --typescript

Which terms did you search for in User Guide?

n/a

Environment

Environment Info:

  System:
    OS: macOS 10.14.4
    CPU: x64 Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz
  Binaries:
    Node: 11.12.0 - ~/.nvm/versions/node/v11.12.0/bin/node
    Yarn: 1.15.2 - /usr/local/bin/yarn
    npm: 6.7.0 - ~/.nvm/versions/node/v11.12.0/bin/npm
  Browsers:
    Chrome: 73.0.3683.103
    Safari: 12.1
  npmPackages:
    react: ^16.8.6 => 16.8.6
    react-dom: ^16.8.6 => 16.8.6
    react-scripts: 3.0.0 => 3.0.0
  npmGlobalPackages:
    create-react-app: Not Found

Steps to Reproduce

1. create-react-app cra-coverage-example --typescript
2. yarn test --coverage

Expected Behavior

test coverage would be output

Actual Behavior

test coverage is always empty

Reproducible Demo

https://github.com/pete-redmond-cko/cra-coverage-example or you can spin up an app using create react app v.3.0.0 and run yarn test --coverage

[bugzpodder]

If you turn off watch via:
yarn test --coverage --watchAll=false

It will work properly. Looks like a Jest bug. @stipsan

[esturcke]

Thanks @bugzpodder !

This also fixed a regression we had running tests/coverage in Docker causing us to hit up against the fs.inotify.max_user_watches limit. Added --watchAll=false and now our tests complete again.

[azeezat]

If you turn off watch via:
yarn test --coverage --watchAll=false

It will work properly. Looks like a Jest bug. @stipsan

This fixed the issue

[aenciso]

If you turn off watch via:
yarn test --coverage --watchAll=false

It will work properly. Looks like a Jest bug. @stipsan

It doesn't fix it for me though. Still getting empty results

[bugzpodder]

@aenciso can you show your entire command that you ran as well as the line in scripts section of package.json that shows actual command.

[aenciso]

@aenciso can you show your entire command that you ran as well as the line in scripts section of package.json that shows actual command.

From command line I run
yarn test --coverage --watchAll=false

[bugzpodder]

I cannot repo this, please provide more details or a minimal repro demonstrating this issue.

[omguhh]

I'm having the same issue as @aenciso - I think it's a jest bug, it's been brought up as an issue there as well after the latest release. jestjs/jest#8364

I can run all the tests fine and see coverage if I'm using this command
npm t -- --coverage --watchAll=false

but running npm t -- --coverage --watch returns an empty table of results, so I can't really 'watch' for changes when I'm updating a test :(

[mraak]

Jest needs more Jest tests to test the Jest.

[hugomn]

I have the same issue and can confirm that --watchAll=false temporarily solves the issue. But it's not a good solution because I cannot use watch at all, together with the coverage.

[bugzpodder]

Can you elaborate on your last statement

[hugomn]

@bugzpodder the only way to have coverage displayed is disabling watch. So when you are working on tests, trying to fix coverage issues, you'll need to re-run all tests every time. That's why I said it's only a temporary solution, but the bug is still there.

[bugzpodder]

As a workaround, you can temporarily modify the component file (or whichever file you are trying to add coverage for) and then the coverage will show up.