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Question: flow + jest #3904

gsar-mdsol opened this Issue Jan 23, 2018 · 5 comments


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gsar-mdsol commented Jan 23, 2018

Do someone have a quick idea how to force flow-typed to install the definitions of jest? I do not see this mentioned in the README, and as jest is not a dependency of my project flow-typed install does not help much.

@gaearon gaearon self-assigned this Jan 23, 2018


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mcjohnalds commented Feb 11, 2018

  1. Look at yarn.lock to see which version of jest your project is using, in my case it was 20.0.4
  2. yarn add jest@20.0.4 && flow-typed install

It's important to only install the version of jest that CRA is already using otherwise yarn test will error.


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dashed commented Feb 21, 2018


It's better to have a peerDependency in your package.json:

  "peerDependencies": {
    "jest": "20.x"

Then flow-typed update --skip


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marcusegues commented Apr 6, 2018

To solve (temporarily I think) the issue of Flow finding errors in a Jest test file with the // @flow annotation at the top, I did:
npm install -g flow-typed
flow-typed install jest@20.0.4

When create-react-app is upgraded to use a new version of Jest, I would have to get the potential new type definitions by running the flowtyped install command above, correct? Is this intended? Isn't CRA supposed to work out of the box without this sort of thing?


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tylerthehaas commented May 31, 2018

I think the issue here is there is no way for flow-typed to install the dependencies of react-scripts which is where jest is pulled in from. This could be alleviated if there was a script added that did this likenpm run flow-typed. However it seems that the current thinking is to only have a very limited number of npm scripts included with create-react-app. Would be nice to have a solution to where we didn't have to include dependencies we wanted flow types for twice. Once in our own project dependencies and once by react-scripts.


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stale bot commented Nov 2, 2018

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in 7 days if no further activity occurs.

@stale stale bot added the stale label Nov 2, 2018

@Timer Timer closed this Nov 2, 2018

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