How to get test coverage from Jest while testing React.js App?

Question

We need to check test coverage for our React.js app and ideally get lcov.info output to send to a third-party coverage tracker like Coveralls or CodeClimate

Its unclear from the Jest API how to get test coverage information when running tests.

There's an Open Issue on GitHub: https://github.com/facebook/jest/issues/101 and associated Pull Request: https://github.com/facebook/jest/pull/178 but the PR still has not been merged by the Jest core team.

Is there an alternative way of getting coverage info that works today?

Note: I'm aware of @adrian-adkison suggestion in: https://stackoverflow.com/a/27479903/1148249 but @hankhsiao's fork is quite out-of-date with jest-cli since he submitted the Pull Request 2.5 months ago...

score 36 · Answer 1 · answered Apr 05 '20 at 10:27

36

npm test -- --coverage

note that extra -- in the middle, docs

answered Apr 05 '20 at 10:27

Ali Faris

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what does that extra `--` do? – Clyde D'Souza Mar 18 '21 at 07:24
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whatever follows -- are arguments that npm will pass to the script being run, in this case probably `jest`. Will result in `jest --coverage` – lbarbosa Aug 13 '21 at 15:16
This should be the accepted answer. – paddotk Nov 08 '21 at 11:49
I have a react app created from `create-react-app`, to get the coverage I ran `npm test -- --coverage` and it worked for me, Thanks. – Rajkumar M Feb 16 '22 at 09:30

score 18 · Accepted Answer · answered Mar 04 '15 at 17:38

18

@hankhsiao's fork has been merged. I have been using the latest https://github.com/facebook/jest and getting great results.

jest --coverage

answered Mar 04 '15 at 17:38

Matt Norris

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This failed for TypeScript React project. – Montacer Dkhilali Apr 29 '21 at 10:14

score 4 · Answer 3 · edited Aug 24 '21 at 08:00

4

In your package.json under the script section add this piece of code -

test: react-scripts test --coverage

edited Aug 24 '21 at 08:00

Dharman

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answered Aug 24 '21 at 07:55

akash ingole

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score 1 · Answer 4 · answered Aug 03 '16 at 09:49

You can either run jest through

jest --coverage

or you can also set "collectCoverage" to true in your jest configuration inside your package.json. This way the coverage report will be generated everytime you run jest.

Although you should know that this can increase the time taken for your tests to run significantly.

score 1 · Answer 5 · answered Aug 22 '23 at 06:36

1

package.json

"scripts": {
    ...
    "test": "react-scripts test",
    ...
  },

run command

npm run test -- --watchAll=false  --coverage

you can also check in details

 /coverage/icov-report/src/...<file>.html

answered Aug 22 '23 at 06:36

Manthan Vaghani

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score 0 · Answer 6 · answered Aug 02 '22 at 06:36

0

In my package.json

 "scripts": {
    ...
    "test": "react-scripts test",
    "test:coverage": "react-scripts test --coverage",
    ...
  },

to see test coverage

yarn test:coverage

answered Aug 02 '22 at 06:36

Sanka Sanjeewa

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How to get test coverage from Jest while testing React.js App?

6 Answers6