DIfferent versions of Jest

[KevinBurton]

I have a CRA created app that I tried to install Jest as per the package.json in the course but when I install it an subsequently run the tests I get:

PS C:\Users\RKevi\source\repos\GreatState\GreatState\ClientApp> yarn test
yarn run v1.22.4
$ cross-env CI=true react-scripts test --env=jest-environment-jsdom-sixteen --coverage

There might be a problem with the project dependency tree.
It is likely not a bug in Create React App, but something you need to fix locally.

The react-scripts package provided by Create React App requires a dependency:

  "jest": "24.9.0"

Don't try to install it manually: your package manager does it automatically.
However, a different version of jest was detected higher up in the tree:

  C:\Users\RKevi\source\repos\GreatState\GreatState\ClientApp\node_modules\jest (version: 26.1.0)

Manually installing incompatible versions is known to cause hard-to-debug issues.

If you would prefer to ignore this check, add SKIP_PREFLIGHT_CHECK=true to an .env file in your project.
That will permanently disable this message but you might encounter other issues.

To fix the dependency tree, try following the steps below in the exact order:

  1. Delete package-lock.json (not package.json!) and/or yarn.lock in your project folder.
  2. Delete node_modules in your project folder.
  3. Remove "jest" from dependencies and/or devDependencies in the package.json file in your project folder.
  4. Run npm install or yarn, depending on the package manager you use.

In most cases, this should be enough to fix the problem.
If this has not helped, there are a few other things you can try:

  5. If you used npm, install yarn (http://yarnpkg.com/) and repeat the above steps with it instead.
     This may help because npm has known issues with package hoisting which may get resolved in future versions.

  6. Check if C:\Users\RKevi\source\repos\GreatState\GreatState\ClientApp\node_modules\jest is outside your project directory.
     For example, you might have accidentally installed something in your home folder.

  7. Try running npm ls jest in your project folder.
     This will tell you which other package (apart from the expected react-scripts) installed jest.

If nothing else helps, add SKIP_PREFLIGHT_CHECK=true to an .env file in your project.
That would permanently disable this preflight check in case you want to proceed anyway.

P.S. We know this message is long but please read the steps above :-) We hope you find them helpful!

error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

I tried the suggestions in the error list and indeed found multiple dependencies. Running 'yarn why jest' gives me:

PS C:\Users\RKevi\source\repos\GreatState\GreatState\ClientApp> yarn why jest
yarn why v1.22.4
[1/4] Why do we have the module "jest"...?
[2/4] Initialising dependency graph...
[3/4] Finding dependency...
[4/4] Calculating file sizes...
=> Found "jest@24.9.0"
info Reasons this module exists
   - "react-scripts" depends on it
   - Hoisted from "react-scripts#jest"
info Disk size without dependencies: "100KB"
info Disk size with unique dependencies: "3.69MB"
info Disk size with transitive dependencies: "86.24MB"
info Number of shared dependencies: 273
=> Found "kcd-scripts#jest@26.1.0"
info This module exists because "kcd-scripts" depends on it.
Done in 3.80s.

So based on my understanding (which is limited) it seems that kcd-scripts is referencing the latest Jest and react-scripts is referencing an earlier one. It seems that I need to update react-scripts dependency but I am not sure how.

If I try just using kcd-scripts I get a number of errors in the tests but I don't see any explanation. Errors mainly about toBeInTheDocument not a function

TypeError: expect(...).toBeInTheDocument is not a function Thank you.

Kevin

[nickserv]

You need to uninstall jest and use the version from react-scripts.

[KevinBurton]

Nick,

Not to drag this on but I get a warning that ts-jest requires jest >= 26 this is a typescript project and I am not sure how to tell ts-jest that jest is installed with react-scripts?

Kevin

On Mon, Jul 6, 2020 at 4:06 PM Nick McCurdy notifications@github.com wrote:

You need to uninstall jest and use the version from react-scripts.

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[nickserv]

You don't need ts-jest as react-scripts already supports TypeScript, so you can also uninstall that.

[KevinBurton]

jest-runner-eslint? Again from the course.

On Tue, Jul 7, 2020 at 2:17 AM Nick McCurdy notifications@github.com wrote:

You don't need ts-jest, you can also uninstall that.

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[nickserv]

You generally shouldn't need any of this tooling, it's handled by CRA (except for Prettier which you can run on your own via a script or extension if you want)