Add src/setupTests.js to specify environment setup for Jest (#545) #548

gaelollivier · 2016-09-02T14:38:13Z

Test plan

Run npm run create-react-app my-app and in the generated App.js, add something like localStorage.getItem('test');. Run npm test, it should fail because localStorage is undefined. Add a setupTests.js in src that looks like this:

const localStorageMock = {
  getItem: jest.fn(),
  setItem: jest.fn(),
  clear: jest.fn()
};
global.localStorage = localStorageMock

Then run npm test again (you need to re-run the command in order to have the setupTests.js added to Jest config) and it should pass.
You can also simply add a setupTests.js that does a console.log('Hello world') to check it's properly executed before the tests.

ghost · 2016-09-02T14:38:25Z

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gaearon · 2016-09-02T14:40:54Z

Can you please specify the test plan?

See https://github.com/facebookincubator/create-react-app/blob/master/CONTRIBUTING.md#submitting-a-pull-request:

Please also provide a test plan, i.e. specify how you verified that your addition works.

ghost · 2016-09-02T14:44:36Z

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Facebook open source project. Thanks!

gaelollivier · 2016-09-02T14:48:35Z

Test plan added to the initial PR description:

Test plan

Run npm run create-react-app my-app. The template setupTests.js is added in src. Any code in this file should be executed when you run your tests via npm test (for example, add a console.log("Hello world!");, this should be printed in the tests report). If you remove the file, npm test still works as before.

gaearon · 2016-09-02T15:05:48Z

template/src/setupTests.js

@@ -0,0 +1,4 @@
+/**


I think we shouldn’t ship this by default. It’s a little bit advanced feature, and it’s fine to just document it. Can you add relevant documentation section to template/README.md instead?

gaelollivier · 2016-09-02T16:20:42Z

Removed the sample 'setupTests.js' and added docs to the README.md

gaearon · 2016-09-02T16:56:08Z

Sorry for the trouble but I just merged another set of changes that made this conflict.
Could you please rebase?

gaearon · 2016-09-02T16:56:38Z

template/README.md

@@ -671,6 +672,22 @@ import { expect } from 'chai';

 and then use them in your tests like you normally do.

+### Test environment setup


Let’s call this ### Initializing Test Environment

gaelollivier · 2016-09-02T18:46:52Z

Fixed doc title and conflicts ✅

gaearon · 2016-09-02T18:50:25Z

template/README.md

@@ -674,6 +675,22 @@ import { expect } from 'chai';

 and then use them in your tests like you normally do.

+### Initializing Test Environment
+


Please add “>Note: this feature is available since [email protected]” here. You can copy and paste an existing similar notes and change the version.

…#545)

gaearon · 2016-09-02T19:27:14Z

Awesome. Thank you.

cpojer · 2016-09-02T19:46:12Z

scripts/utils/createJestConfig.js

  const config = {
    moduleNameMapper: {
      '^[./a-zA-Z0-9$_-]+\\.(jpg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm)$': resolve('config/jest/FileStub.js'),
      '^[./a-zA-Z0-9$_-]+\\.css$': resolve('config/jest/CSSStub.js')
    },
    scriptPreprocessor: resolve('config/jest/transform.js'),
-    setupFiles: [resolve('config/polyfills.js')],
+    setupFiles: setupFiles,


nit: you don't need the : setupFiles piece here because of object short notation.

I’m not sure Node 4 supports it, does it?

True, wasn't sure of what es6 features I could use there since there are some "var" elsewhere in the code :s

yes, it does! Node 4 supports let/var as well as object short notation and arrow functions.

gaearon · 2016-09-02T21:19:16Z

Out in 0.4.0.
See the release notes!

…#545) (facebook#548)