Jest doesn’t respect Node resolution when looking for the CLI

[gaearon]

This is related to #5119 (comment).

Our react-scripts package from Create React App depends on jest and runs it using the Node API. So jest is generally a dependency.

However, people often install top-level jest in their project (mostly because they don’t know it won’t work), and this breaks their setup with obscure errors like #5119. Their tree looks something like:

├── [email protected] 
└─┬ [email protected]
  └── [email protected] 

Ideally, top-level jest installations shouldn't break the copy of jest in react-scripts. This is a general assumption that typically holds true in the Node ecosystem: different versions of the same subdependency can coexist in different parts of the tree, and not break each other as long as you don’t mix their state.

In the case of Jest, it breaks because Jest uses <process.cwd()>/node_modules/jest-cli as the location of the CLI. Since in our project, process.cwd() is its root, Jest 22 “finds” jest-cli from Jest 20 and mistakingly uses it instead of its own copy of jest-cli:

├── [email protected] 
└─┬ [email protected] // <-- this is the calling code
  └── [email protected]             

├── [email protected] 
└─┬ [email protected] 
  └── [email protected] // <-- it calls Node API of this copy 

├── [email protected] // <-- but the inner copy "finds" the CLI from this copy and breaks
└─┬ [email protected] 
  └── [email protected]

I don’t know if this is intentional. Maybe this has to do with multi-project runner? Regardless, it would be nice if Jest either supported this, or failed with a clear message when Node API of one version of Jest resolves to the CLI code of another version of Jest.

[SimenB]

This was introduced back in 39356eb

[gaearon]

Wow, history. I think this makes sense if the launched CLI is global (outside of CWD) but the found CLI is local. However it doesn't make sense to me if both of them are inside of CWD.

[SimenB]

I wonder if using https://www.npmjs.com/package/import-local would fix it.

[SimenB]

See #5304.

[SimenB]

We have the same issue with babel-jest, FWIW. See (esp. line 119): https://github.com/facebook/jest/blob/3ffc99e02d4b1ecad9d0f5ec2e228bddc8e7210b/packages/jest-config/src/normalize.js#L96-L125

If people install a babel-jest manually, we require that instead of our own. This is the reason for e.g. #5295 (comment).

Should we fix this?

[Merovex]

I just started a new CRA and ran into the missing jest-cli issue and "TypeError: environment.setup is not a function" (also noob to React)

  "dependencies": {
    "bootstrap": "^4.0.0",
    "jest-cli": "^22.4.2",
    "jquery": "^3.3.1",
    "node-sass-chokidar": "^1.1.0",
    "npm-run-all": "^4.1.2",
    "popper.js": "^1.14.1",
    "react": "^16.2.0",
    "react-dom": "^16.2.0",
    "react-router": "^4.2.0",
    "react-router-dom": "^4.2.2",
    "react-scripts": "1.1.1",
    "react-transition-group": "^2.2.1",
    "reactstrap": "^4.8.0"
  },

Turns out, I had to remove --env=jsdom from my script:

"scripts": {
    "start": "npm-run-all -p watch-css start-js",
    "start-js": "react-scripts start",
    "build": "npm-run-all build-css build-js",
    "build-js": "react-scripts build",
    "test": "react-scripts test",
    "NOeject": "react-scripts eject",
    "test:debug": "react-scripts --inspect-brk test --runInBand --env=jsdom",
    "jest-enzyme": "^6.0.0"
  },

[SimenB]

CRA comes with jest built in. You need to remove it from your own package.json. See facebook/create-react-app#1795 and the many linked discussions within

[Merovex]

Yeah, that's not the optimal answer. I read facebook/create-react-app#1795, and the many linked discussions. Turns out that --env=jsdom was throwing the "TypeError: environment.setup" error. I removed it and got to bliss.

This is a virgin CRA app, nothing of note added but the packages. Following the advice of "removing Jest," which wasn't in my packages at any rate...

"dependencies": {
    "bootstrap": "^4.0.0",
    "jquery": "^3.3.1",
    "node-sass-chokidar": "^1.1.0",
    "npm-run-all": "^4.1.2",
    "popper.js": "^1.14.1",
    "react": "^16.2.0",
    "react-dom": "^16.2.0",
    "react-router": "^4.2.0",
    "react-router-dom": "^4.2.2",
    "react-scripts": "1.1.1",
    "react-transition-group": "^2.2.1",
    "reactstrap": "^4.8.0"
  },

Yields:

> react-scripts test

module.js:559
    throw err;
    ^

Error: Cannot find module '/Users/.../node_modules/jest-cli'
    at Function.Module._resolveFilename (module.js:557:15)
    at Function.Module._load (module.js:484:25)
    at Module.require (module.js:606:17)
    at require (internal/module.js:11:18)
   <...etc...?
npm ERR! Test failed.  See above for more details.

I install a few packages to minimally get past errors resulting in:

  "dependencies": {
    "bootstrap": "^4.0.0",
    "enzyme": "^3.3.0",
    "enzyme-adapter-react-16": "^1.1.1",
    "jest-cli": "^22.4.2",
    "jest-enzyme": "^6.0.0",
    "jquery": "^3.3.1",
    "node-sass-chokidar": "^1.1.0",
    "npm-run-all": "^4.1.2",
    "popper.js": "^1.14.1",
    "react": "^16.2.0",
    "react-dom": "^16.2.0",
    "react-router": "^4.2.0",
    "react-router-dom": "^4.2.2",
    "react-scripts": "1.1.1",
    "react-transition-group": "^2.2.1",
    "reactstrap": "^4.8.0"
  },

and a test that should properly fail

 FAIL  src/App.test.js
  ✓ renders without crashing (3ms)
  ✕ renders welcome message (13ms)

  ● renders welcome message

    expect(received).toEqual(expected)
    
    Expected value to equal:
      true
    Received:
      false

      29 |   const welcome = <h2>Welcome to React</h2>;
      30 |   // expect(wrapper.contains(welcome)).to.equal(true);
    > 31 |   expect(wrapper.contains(welcome)).toEqual(true);
      32 | });
      33 | 
      
      at Object.<anonymous>.it (src/App.test.js:31:37)

[SimenB]

You can't have jest-cli in your own package.json when using CRA. You should remove it, as well as any lockfile, and run install again

[gaearon]

To folks commenting here: Jest tracker isn't the best place to report issues about CRA :-) This way we don't hear about them and people spend weeks with broken setups while we're completely unaware. Please file an issue in CRA itself.

[gaearon]

I published [email protected] which should fix environment.dispose is not a function for you.

https://github.com/facebook/create-react-app/releases/tag/v1.1.3

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