test coverage is empty - v3.0.0

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

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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

[mraak]

Jest needs more Jest tests to test the Jest.