Add some docs on using `jest.mock(...)` #5648

danawoodman · 2018-02-23T22:59:08Z

Summary

I find the current docs on mocking lacking in the area of mocking an existing module. The hope is this example will show people a simple, real-world way to mock node modules (whether from npm or in their own projects).

I looked through all the docs and couldn't find a clear example like this so I hope it is helpful to others!

Test plan

Not relevant

facebook-github-bot · 2018-02-23T22:59:30Z

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danawoodman · 2018-02-23T23:46:24Z

No idea why this would break CircleCI, must be some unrelated issue

facebook-github-bot · 2018-02-23T23:52:10Z

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

SimenB · 2018-02-24T11:18:42Z

@danawoodman run yarn lint:md locally to fix CI 🙂

rickhanlonii

Hey @danawoodman, thanks for working to improve the Jest docs!

I left a couple comments and I'm also curious:

Have you seen these docs (they are pretty new)
Do you think the additions here duplicate any of the information in those docs?
Is it possible to merge the new information into those docs instead?

rickhanlonii · 2018-02-24T15:04:59Z

docs/MockFunctions.md

+
+Now, in order to test this method without actually hitting the API (and thus creating slow and fragile tests), we can use the `jest.mock(...)` function to automatically mock the axios module.
+
+Once we mock the module we can spy on the `.get` method and provide a `mockImplementation` that returns the data we want our test to assert against. In effect, we are saying that we want axios.get('/users.json') to return a fake response.


When you mock the module with jest.mock, then axios.get is already set to a mock

Since that's the case, you don't want to spy on it since you only need to set the mock implementation:

import axios from 'axios'; // set all exported functions to jest.fn() jest.mock('axios'); axios.get.mockImpementation(() => Promise.resolve({ foo: 'bar'})); // also an option instead axios.get.mockReturnValue(Promise.resolve({ foo: 'bar'}));

Nice, learning a lot of jest stuff in this PR (that isn't clear in the docs!)

rickhanlonii · 2018-02-24T15:06:05Z

docs/MockFunctions.md

+  const resp = Promise.resolve({ data: [{ name: 'Bob' }] })
+  jest.spyOn(axios, 'get').mockImplementationOnce(() => resp)
+
+  return Users.all().then(users => expect(users).toEqual(resp.data))


Is resp.data correct? resp is the promise, not the data returned

You're right. Problem with copy paste!

Wait, resp.data is correct since Users.all returns resp.data not resp

lukeapage · 2018-02-25T17:02:00Z

docs/MockFunctions.md

+
+test('should fetch users', () => {
+  const resp = Promise.resolve({ data: [{ name: 'Bob' }] })
+  jest.spyOn(axios, 'get').mockImplementationOnce(() => resp)


wouldn't this be

axios.get.mockReturnValue(resp);

since it is already mocked..?

Nice, even simpler!

danawoodman · 2018-02-27T21:43:38Z

@rickhanlonii @lukeapage just updated the PR with suggested changes, let me know if it looks better?

Regarding your questions, I think this location makes the most sense since it isn't specific to ES6 classes but mocking in general. The Mock Functions page is going to be seen by more people most likely as well and considering it lakes a real-world example, I think having this example (or something functionally similar) is very helpful for new users. Plus, showing an example that looks like real code in a living application should help making it "click" for people (it was for me!). Let me know what you think!

codecov-io · 2018-02-27T22:02:34Z

Codecov Report

Merging #5648 into master will not change coverage.
The diff coverage is n/a.

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SimenB · 2018-02-28T08:57:52Z

docs/MockFunctions.md

+  // or you could use the follwing depending on your use case:
+  // axios.get.mockImpementation(() => resp)
+
+  return Users.all().then(users => expect(users).toEqual(resp.data));


.toEqual(resp.data)) won't work, will it? resp is a promise, so it has no .data

Yep, @danawoodman this fails as written (we also discussed this here):

Ugh... doh sorry about that. Let me clean it up again 🤦‍♂️

SimenB · 2018-02-28T08:59:04Z

docs/MockFunctions.md

+creating slow and fragile tests), we can use the `jest.mock(...)` function to
+automatically mock the axios module.
+
+Once we mock the module we can spy on the `.get` method and provide a


we don't spy, what about "Once we mock the module we can provide a mockImplementation for .get that returns..."?

@SimenB I updated to be more clear and mentioned mockReturnValue 👍

I find the current docs on mocking lacking in the area of mocking an existing module. The hope is this example will show people a simple, real-world way to mock node modules (whether from npm or in their own projects). I looked through all the docs and couldn't find a clear example like this so I hope it is helpful to others!

danawoodman · 2018-03-01T22:02:08Z

@rickhanlonii for some reason yarn lint:md now fails locally with:

yarn lint:md
yarn lint:md v0.23.2
$ yarn --silent lint:md:ci --fix
error `install` has been replaced with `add` to add new dependencies. Run "yarn add lint:md:ci" instead.
error Command failed with exit code 1.

Any idea why?

EDIT: Just ran yarn lint:md:ci -- --fix to get around it for now

danawoodman · 2018-03-01T22:04:40Z

@rickhanlonii just pushed a fix and 🤞 it works this time! 😆

rickhanlonii · 2018-03-01T22:23:21Z

@danawoodman looks like you're on an old version of yarn

SimenB · 2018-03-01T22:25:58Z

docs/MockFunctions.md

+
+test('should fetch users', () => {
+  const resp = {data: [{name: 'Bob'}]};
+  axios.get.mockReturnValue(Promise.resolve(resp));


FWIW we have a shorthand for it: https://facebook.github.io/jest/docs/en/mock-function-api.html#mockfnmockresolvedvaluevalue

Up to you if you want to use it, but maybe mention it in a comment?

@SimenB man I'm learning a lot in this PR! Pushed an update to add that!

danawoodman · 2018-03-01T22:29:12Z

Ok, hope this is ready to merge 😆

rickhanlonii · 2018-03-01T23:02:06Z

Thanks @danawoodman and congrats on your first contrib!

danawoodman · 2018-03-02T17:01:02Z

Awesome, thanks!! 🕺🎉

This Pull Request updates dependency [jest](https://github.com/facebook/jest) from `~22.4.0` to `~23.0.0` <details> <summary>Release Notes</summary> ### [`v23.0.0`](https://github.com/facebook/jest/blob/master/CHANGELOG.md#2300) [Compare Source](jestjs/jest@2745e3e...614f739) ##### Features * `[expect]` Expose `getObjectSubset`, `iterableEquality`, and `subsetEquality` ([#6210](`jestjs/jest#6210)) * `[jest-snapshot]` Add snapshot property matchers ([#6210](`jestjs/jest#6210)) * `[jest-config]` Support jest-preset.js files within Node modules ([#6185](`jestjs/jest#6185)) * `[jest-cli]` Add `--detectOpenHandles` flag which enables Jest to potentially track down handles keeping it open after tests are complete. ([#6130](`jestjs/jest#6130)) * `[jest-jasmine2]` Add data driven testing based on `jest-each` ([#6102](`jestjs/jest#6102)) * `[jest-matcher-utils]` Change "suggest to equal" message to be more advisory ([#6103](`jestjs/jest#6103)) * `[jest-message-util]` Don't ignore messages with `vendor` anymore ([#6117](`jestjs/jest#6117)) * `[jest-validate]` Get rid of `jest-config` dependency ([#6067](`jestjs/jest#6067)) * `[jest-validate]` Adds option to inject `deprecationEntries` ([#6067](`jestjs/jest#6067)) * `[jest-snapshot]` [**BREAKING**] Concatenate name of test, optional snapshot name and count ([#6015](`jestjs/jest#6015)) * `[jest-runtime]` Allow for transform plugins to skip the definition process method if createTransformer method was defined. ([#5999](`jestjs/jest#5999)) * `[expect]` Add stack trace for async errors ([#6008](`jestjs/jest#6008)) * `[jest-jasmine2]` Add stack trace for timeouts ([#6008](`jestjs/jest#6008)) * `[jest-jasmine2]` Add stack trace for thrown non-`Error`s ([#6008](`jestjs/jest#6008)) * `[jest-runtime]` Prevent modules from marking themselves as their own parent ([#5235](`jestjs/jest#5235)) * `[jest-mock]` Add support for auto-mocking generator functions ([#5983](`jestjs/jest#5983)) * `[expect]` Add support for async matchers ([#5919](`jestjs/jest#5919)) * `[expect]` Suggest toContainEqual ([#5948](`jestjs/jest#5953)) * `[jest-config]` Export Jest's default options ([#5948](`jestjs/jest#5948)) * `[jest-editor-support]` Move `coverage` to `ProjectWorkspace.collectCoverage` ([#5929](`jestjs/jest#5929)) * `[jest-editor-support]` Add `coverage` option to runner ([#5836](`jestjs/jest#5836)) * `[jest-haste-map]` Support extracting dynamic `import`s ([#5883](`jestjs/jest#5883)) * `[expect]` Improve output format for mismatchedArgs in mock/spy calls. ([#5846](`jestjs/jest#5846)) * `[jest-cli]` Add support for using `--coverage` in combination with watch mode, `--onlyChanged`, `--findRelatedTests` and more ([#5601](`jestjs/jest#5601)) * `[jest-jasmine2]` [**BREAKING**] Adds error throwing and descriptive errors to `it`/ `test` for invalid arguments. `[jest-circus]` Adds error throwing and descriptive errors to `it`/ `test` for invalid arguments ([#5558](`jestjs/jest#5558)) * `[jest-matcher-utils]` Add `isNot` option to `matcherHint` function ([#5512](`jestjs/jest#5512)) * `[jest-config]` Add `<rootDir>` to runtime files not found error report ([#5693](`jestjs/jest#5693)) * `[expect]` Make toThrow matcher pass only if Error object is returned from promises ([#5670](`jestjs/jest#5670)) * `[expect]` Add isError to utils ([#5670](`jestjs/jest#5670)) * `[expect]` Add inverse matchers (`expect.not.arrayContaining`, etc., [#5517](`jestjs/jest#5517)) * `[expect]` `expect.extend` now also extends asymmetric matchers ([#5503](`jestjs/jest#5503)) * `[jest-mock]` Update `spyOnProperty` to support spying on the prototype chain ([#5753](`jestjs/jest#5753)) * `[jest-mock]` Add tracking of return values in the `mock` property ([#5752](`jestjs/jest#5752)) * `[jest-mock]` Add tracking of thrown errors in the `mock` property ([#5764](`jestjs/jest#5764)) * `[expect]`Add nthCalledWith spy matcher ([#5605](`jestjs/jest#5605)) * `[jest-cli]` Add `isSerial` property that runners can expose to specify that they can not run in parallel ([#5706](`jestjs/jest#5706)) * `[expect]` Add `.toBeCalledTimes` and `toHaveBeenNthCalledWith` aliases ([#5826](`jestjs/jest#5826)) * `[jest-cli]` Interactive Snapshot Mode improvements ([#5864](`jestjs/jest#5864)) * `[jest-editor-support]` Add `no-color` option to runner ([#5909](`jestjs/jest#5909)) * `[jest-jasmine2]` Pretty-print non-Error object errors ([#5980](`jestjs/jest#5980)) * `[jest-message-util]` Include column in stack frames ([#5889](`jestjs/jest#5889)) * `[expect]` Introduce toStrictEqual ([#6032](`jestjs/jest#6032)) * `[expect]` Add return matchers ([#5879](`jestjs/jest#5879)) * `[jest-cli]` Improve snapshot summaries ([#6181](`jestjs/jest#6181)) * `[expect]` Include custom mock names in error messages ([#6199](`jestjs/jest#6199)) * `[jest-diff]` Support returning diff from oneline strings ([#6221](`jestjs/jest#6221)) * `[expect]` Improve return matchers ([#6172](`jestjs/jest#6172)) * `[jest-cli]` Overhaul watch plugin hooks names ([#6249](`jestjs/jest#6249)) * `[jest-mock]` Include tracked call results in serialized mock ([#6244](`jestjs/jest#6244)) ##### Fixes * `[jest-cli]` Fix stdin encoding to utf8 for watch plugins. ([#6253](`jestjs/jest#6253)) * `[expect]` Better detection of DOM Nodes for equality ([#6246](`jestjs/jest#6246)) * `[jest-cli]` Fix misleading action description for F key when in "only failed tests" mode. ([#6167](`jestjs/jest#6167)) * `[jest-worker]` Stick calls to workers before processing them ([#6073](`jestjs/jest#6073)) * `[babel-plugin-jest-hoist]` Allow using `console` global variable ([#6075](`jestjs/jest#6075)) * `[jest-jasmine2]` Always remove node core message from assert stack traces ([#6055](`jestjs/jest#6055)) * `[expect]` Add stack trace when `expect.assertions` and `expect.hasAssertions` causes test failures. ([#5997](`jestjs/jest#5997)) * `[jest-runtime]` Throw a more useful error when trying to require modules after the test environment is torn down ([#5888](`jestjs/jest#5888)) * `[jest-mock]` [**BREAKING**] Replace timestamps with `invocationCallOrder` ([#5867](`jestjs/jest#5867)) * `[jest-jasmine2]` Install `sourcemap-support` into normal runtime to catch runtime errors ([#5945](`jestjs/jest#5945)) * `[jest-jasmine2]` Added assertion error handling inside `afterAll hook` ([#5884](`jestjs/jest#5884)) * `[jest-cli]` Remove the notifier actions in case of failure when not in watch mode. ([#5861](`jestjs/jest#5861)) * `[jest-mock]` Extend .toHaveBeenCalled return message with outcome ([#5951](`jestjs/jest#5951)) * `[jest-runner]` Assign `process.env.JEST_WORKER_ID="1"` when in runInBand mode ([#5860](`jestjs/jest#5860)) * `[jest-cli]` Add descriptive error message when trying to use `globalSetup`/`globalTeardown` file that doesn't export a function. ([#5835](`jestjs/jest#5835)) * `[expect]` Do not rely on `instanceof RegExp`, since it will not work for RegExps created inside of a different VM ([#5729](`jestjs/jest#5729)) * `[jest-resolve]` Update node module resolution algorithm to correctly handle symlinked paths ([#5085](`jestjs/jest#5085)) * `[jest-editor-support]` Update `Settings` to use spawn in shell option ([#5658](`jestjs/jest#5658)) * `[jest-cli]` Improve the error message when 2 projects resolve to the same config ([#5674](`jestjs/jest#5674)) * `[jest-runtime]` remove retainLines from coverage instrumentation ([#5692](`jestjs/jest#5692)) * `[jest-cli]` Fix update snapshot issue when using watchAll ([#5696](`jestjs/jest#5696)) * `[expect]` Fix rejects.not matcher ([#5670](`jestjs/jest#5670)) * `[jest-runtime]` Prevent Babel warnings on large files ([#5702](`jestjs/jest#5702)) * `[jest-mock]` Prevent `mockRejectedValue` from causing unhandled rejection ([#5720](`jestjs/jest#5720)) * `[pretty-format]` Handle React fragments better ([#5816](`jestjs/jest#5816)) * `[pretty-format]` Handle formatting of `React.forwardRef` and `Context` components ([#6093](`jestjs/jest#6093)) * `[jest-cli]` Switch collectCoverageFrom back to a string ([#5914](`jestjs/jest#5914)) * `[jest-regex-util]` Fix handling regex symbols in tests path on Windows ([#5941](`jestjs/jest#5941)) * `[jest-util]` Fix handling of NaN/Infinity in mock timer delay ([#5966](`jestjs/jest#5966)) * `[jest-resolve]` Generalise test for package main entries equivalent to ".". ([#5968](`jestjs/jest#5968)) * `[jest-config]` Ensure that custom resolvers are used when resolving the configuration ([#5976](`jestjs/jest#5976)) * `[website]` Fix website docs ([#5853](`jestjs/jest#5853)) * `[expect]` Fix isEqual Set and Map to compare object values and keys regardless of order ([#6150](`jestjs/jest#6150)) * `[pretty-format]` [**BREAKING**] Remove undefined props from React elements ([#6162](`jestjs/jest#6162)) * `[jest-haste-map]` Properly resolve mocked node modules without package.json defined ([#6232](`jestjs/jest#6232)) ##### Chore & Maintenance * `[jest-runner]` Move sourcemap installation from `jest-jasmine2` to `jest-runner` ([#6176](`jestjs/jest#6176)) * `[jest-cli]` Use yargs's built-in `version` instead of rolling our own ([#6215](`jestjs/jest#6215)) * `[docs]` Add explanation on how to mock methods not implemented in JSDOM * `[jest-jasmine2]` Simplify `Env.execute` and TreeProcessor to setup and clean resources for the top suite the same way as for all of the children suites ([#5885](`jestjs/jest#5885)) * `[babel-jest]` [**BREAKING**] Always return object from transformer ([#5991](`jestjs/jest#5991)) * `[*]` Run Prettier on compiled output ([#5858](`jestjs/jest#3497)) * `[jest-cli]` Add fileChange hook for plugins ([#5708](`jestjs/jest#5708)) * `[docs]` Add docs on using `jest.mock(...)` ([#5648](`jestjs/jest#5648)) * `[docs]` Mention Jest Puppeteer Preset ([#5722](`jestjs/jest#5722)) * `[docs]` Add jest-community section to website ([#5675](`jestjs/jest#5675)) * `[docs]` Add versioned docs for v22.4 ([##5733](https://github.com/facebook/jest/pull/#5733)) * `[docs]` Improve Snapshot Testing Guide ([#5812](`jestjs/jest#5812)) * `[jest-runtime]` [**BREAKING**] Remove `jest.genMockFn` and `jest.genMockFunction` ([#6173](`jestjs/jest#6173)) * `[jest-message-util]` Avoid adding unnecessary indent to blank lines in stack traces ([#6211](`jestjs/jest#6211)) --- </details> --- This PR has been generated by [Renovate Bot](https://renovatebot.com).

This Pull Request updates dependency [jest](https://github.com/facebook/jest) from `~22.4.0` to `~23.0.0` <details> <summary>Release Notes</summary> ### [`v23.0.0`](https://github.com/facebook/jest/blob/master/CHANGELOG.md#2300) [Compare Source](jestjs/jest@2745e3e...v23.0.0) ##### Features * `[expect]` Expose `getObjectSubset`, `iterableEquality`, and `subsetEquality` ([#6210](`jestjs/jest#6210)) * `[jest-snapshot]` Add snapshot property matchers ([#6210](`jestjs/jest#6210)) * `[jest-config]` Support jest-preset.js files within Node modules ([#6185](`jestjs/jest#6185)) * `[jest-cli]` Add `--detectOpenHandles` flag which enables Jest to potentially track down handles keeping it open after tests are complete. ([#6130](`jestjs/jest#6130)) * `[jest-jasmine2]` Add data driven testing based on `jest-each` ([#6102](`jestjs/jest#6102)) * `[jest-matcher-utils]` Change "suggest to equal" message to be more advisory ([#6103](`jestjs/jest#6103)) * `[jest-message-util]` Don't ignore messages with `vendor` anymore ([#6117](`jestjs/jest#6117)) * `[jest-validate]` Get rid of `jest-config` dependency ([#6067](`jestjs/jest#6067)) * `[jest-validate]` Adds option to inject `deprecationEntries` ([#6067](`jestjs/jest#6067)) * `[jest-snapshot]` [**BREAKING**] Concatenate name of test, optional snapshot name and count ([#6015](`jestjs/jest#6015)) * `[jest-runtime]` Allow for transform plugins to skip the definition process method if createTransformer method was defined. ([#5999](`jestjs/jest#5999)) * `[expect]` Add stack trace for async errors ([#6008](`jestjs/jest#6008)) * `[jest-jasmine2]` Add stack trace for timeouts ([#6008](`jestjs/jest#6008)) * `[jest-jasmine2]` Add stack trace for thrown non-`Error`s ([#6008](`jestjs/jest#6008)) * `[jest-runtime]` Prevent modules from marking themselves as their own parent ([#5235](`jestjs/jest#5235)) * `[jest-mock]` Add support for auto-mocking generator functions ([#5983](`jestjs/jest#5983)) * `[expect]` Add support for async matchers ([#5919](`jestjs/jest#5919)) * `[expect]` Suggest toContainEqual ([#5948](`jestjs/jest#5953)) * `[jest-config]` Export Jest's default options ([#5948](`jestjs/jest#5948)) * `[jest-editor-support]` Move `coverage` to `ProjectWorkspace.collectCoverage` ([#5929](`jestjs/jest#5929)) * `[jest-editor-support]` Add `coverage` option to runner ([#5836](`jestjs/jest#5836)) * `[jest-haste-map]` Support extracting dynamic `import`s ([#5883](`jestjs/jest#5883)) * `[expect]` Improve output format for mismatchedArgs in mock/spy calls. ([#5846](`jestjs/jest#5846)) * `[jest-cli]` Add support for using `--coverage` in combination with watch mode, `--onlyChanged`, `--findRelatedTests` and more ([#5601](`jestjs/jest#5601)) * `[jest-jasmine2]` [**BREAKING**] Adds error throwing and descriptive errors to `it`/ `test` for invalid arguments. `[jest-circus]` Adds error throwing and descriptive errors to `it`/ `test` for invalid arguments ([#5558](`jestjs/jest#5558)) * `[jest-matcher-utils]` Add `isNot` option to `matcherHint` function ([#5512](`jestjs/jest#5512)) * `[jest-config]` Add `<rootDir>` to runtime files not found error report ([#5693](`jestjs/jest#5693)) * `[expect]` Make toThrow matcher pass only if Error object is returned from promises ([#5670](`jestjs/jest#5670)) * `[expect]` Add isError to utils ([#5670](`jestjs/jest#5670)) * `[expect]` Add inverse matchers (`expect.not.arrayContaining`, etc., [#5517](`jestjs/jest#5517)) * `[expect]` `expect.extend` now also extends asymmetric matchers ([#5503](`jestjs/jest#5503)) * `[jest-mock]` Update `spyOnProperty` to support spying on the prototype chain ([#5753](`jestjs/jest#5753)) * `[jest-mock]` Add tracking of return values in the `mock` property ([#5752](`jestjs/jest#5752)) * `[jest-mock]` Add tracking of thrown errors in the `mock` property ([#5764](`jestjs/jest#5764)) * `[expect]`Add nthCalledWith spy matcher ([#5605](`jestjs/jest#5605)) * `[jest-cli]` Add `isSerial` property that runners can expose to specify that they can not run in parallel ([#5706](`jestjs/jest#5706)) * `[expect]` Add `.toBeCalledTimes` and `toHaveBeenNthCalledWith` aliases ([#5826](`jestjs/jest#5826)) * `[jest-cli]` Interactive Snapshot Mode improvements ([#5864](`jestjs/jest#5864)) * `[jest-editor-support]` Add `no-color` option to runner ([#5909](`jestjs/jest#5909)) * `[jest-jasmine2]` Pretty-print non-Error object errors ([#5980](`jestjs/jest#5980)) * `[jest-message-util]` Include column in stack frames ([#5889](`jestjs/jest#5889)) * `[expect]` Introduce toStrictEqual ([#6032](`jestjs/jest#6032)) * `[expect]` Add return matchers ([#5879](`jestjs/jest#5879)) * `[jest-cli]` Improve snapshot summaries ([#6181](`jestjs/jest#6181)) * `[expect]` Include custom mock names in error messages ([#6199](`jestjs/jest#6199)) * `[jest-diff]` Support returning diff from oneline strings ([#6221](`jestjs/jest#6221)) * `[expect]` Improve return matchers ([#6172](`jestjs/jest#6172)) * `[jest-cli]` Overhaul watch plugin hooks names ([#6249](`jestjs/jest#6249)) * `[jest-mock]` Include tracked call results in serialized mock ([#6244](`jestjs/jest#6244)) ##### Fixes * `[jest-cli]` Fix stdin encoding to utf8 for watch plugins. ([#6253](`jestjs/jest#6253)) * `[expect]` Better detection of DOM Nodes for equality ([#6246](`jestjs/jest#6246)) * `[jest-cli]` Fix misleading action description for F key when in "only failed tests" mode. ([#6167](`jestjs/jest#6167)) * `[jest-worker]` Stick calls to workers before processing them ([#6073](`jestjs/jest#6073)) * `[babel-plugin-jest-hoist]` Allow using `console` global variable ([#6075](`jestjs/jest#6075)) * `[jest-jasmine2]` Always remove node core message from assert stack traces ([#6055](`jestjs/jest#6055)) * `[expect]` Add stack trace when `expect.assertions` and `expect.hasAssertions` causes test failures. ([#5997](`jestjs/jest#5997)) * `[jest-runtime]` Throw a more useful error when trying to require modules after the test environment is torn down ([#5888](`jestjs/jest#5888)) * `[jest-mock]` [**BREAKING**] Replace timestamps with `invocationCallOrder` ([#5867](`jestjs/jest#5867)) * `[jest-jasmine2]` Install `sourcemap-support` into normal runtime to catch runtime errors ([#5945](`jestjs/jest#5945)) * `[jest-jasmine2]` Added assertion error handling inside `afterAll hook` ([#5884](`jestjs/jest#5884)) * `[jest-cli]` Remove the notifier actions in case of failure when not in watch mode. ([#5861](`jestjs/jest#5861)) * `[jest-mock]` Extend .toHaveBeenCalled return message with outcome ([#5951](`jestjs/jest#5951)) * `[jest-runner]` Assign `process.env.JEST_WORKER_ID="1"` when in runInBand mode ([#5860](`jestjs/jest#5860)) * `[jest-cli]` Add descriptive error message when trying to use `globalSetup`/`globalTeardown` file that doesn't export a function. ([#5835](`jestjs/jest#5835)) * `[expect]` Do not rely on `instanceof RegExp`, since it will not work for RegExps created inside of a different VM ([#5729](`jestjs/jest#5729)) * `[jest-resolve]` Update node module resolution algorithm to correctly handle symlinked paths ([#5085](`jestjs/jest#5085)) * `[jest-editor-support]` Update `Settings` to use spawn in shell option ([#5658](`jestjs/jest#5658)) * `[jest-cli]` Improve the error message when 2 projects resolve to the same config ([#5674](`jestjs/jest#5674)) * `[jest-runtime]` remove retainLines from coverage instrumentation ([#5692](`jestjs/jest#5692)) * `[jest-cli]` Fix update snapshot issue when using watchAll ([#5696](`jestjs/jest#5696)) * `[expect]` Fix rejects.not matcher ([#5670](`jestjs/jest#5670)) * `[jest-runtime]` Prevent Babel warnings on large files ([#5702](`jestjs/jest#5702)) * `[jest-mock]` Prevent `mockRejectedValue` from causing unhandled rejection ([#5720](`jestjs/jest#5720)) * `[pretty-format]` Handle React fragments better ([#5816](`jestjs/jest#5816)) * `[pretty-format]` Handle formatting of `React.forwardRef` and `Context` components ([#6093](`jestjs/jest#6093)) * `[jest-cli]` Switch collectCoverageFrom back to a string ([#5914](`jestjs/jest#5914)) * `[jest-regex-util]` Fix handling regex symbols in tests path on Windows ([#5941](`jestjs/jest#5941)) * `[jest-util]` Fix handling of NaN/Infinity in mock timer delay ([#5966](`jestjs/jest#5966)) * `[jest-resolve]` Generalise test for package main entries equivalent to ".". ([#5968](`jestjs/jest#5968)) * `[jest-config]` Ensure that custom resolvers are used when resolving the configuration ([#5976](`jestjs/jest#5976)) * `[website]` Fix website docs ([#5853](`jestjs/jest#5853)) * `[expect]` Fix isEqual Set and Map to compare object values and keys regardless of order ([#6150](`jestjs/jest#6150)) * `[pretty-format]` [**BREAKING**] Remove undefined props from React elements ([#6162](`jestjs/jest#6162)) * `[jest-haste-map]` Properly resolve mocked node modules without package.json defined ([#6232](`jestjs/jest#6232)) ##### Chore & Maintenance * `[jest-runner]` Move sourcemap installation from `jest-jasmine2` to `jest-runner` ([#6176](`jestjs/jest#6176)) * `[jest-cli]` Use yargs's built-in `version` instead of rolling our own ([#6215](`jestjs/jest#6215)) * `[docs]` Add explanation on how to mock methods not implemented in JSDOM * `[jest-jasmine2]` Simplify `Env.execute` and TreeProcessor to setup and clean resources for the top suite the same way as for all of the children suites ([#5885](`jestjs/jest#5885)) * `[babel-jest]` [**BREAKING**] Always return object from transformer ([#5991](`jestjs/jest#5991)) * `[*]` Run Prettier on compiled output ([#5858](`jestjs/jest#3497)) * `[jest-cli]` Add fileChange hook for plugins ([#5708](`jestjs/jest#5708)) * `[docs]` Add docs on using `jest.mock(...)` ([#5648](`jestjs/jest#5648)) * `[docs]` Mention Jest Puppeteer Preset ([#5722](`jestjs/jest#5722)) * `[docs]` Add jest-community section to website ([#5675](`jestjs/jest#5675)) * `[docs]` Add versioned docs for v22.4 ([##5733](https://github.com/facebook/jest/pull/#5733)) * `[docs]` Improve Snapshot Testing Guide ([#5812](`jestjs/jest#5812)) * `[jest-runtime]` [**BREAKING**] Remove `jest.genMockFn` and `jest.genMockFunction` ([#6173](`jestjs/jest#6173)) * `[jest-message-util]` Avoid adding unnecessary indent to blank lines in stack traces ([#6211](`jestjs/jest#6211)) --- </details> --- This PR has been generated by [Renovate Bot](https://renovatebot.com).

This Pull Request updates dependency [jest](https://github.com/facebook/jest) from `v22.4.3` to `v23.0.1` <details> <summary>Release Notes</summary> ### [`v23.0.1`](https://github.com/facebook/jest/blob/master/CHANGELOG.md#2301) [Compare Source](jestjs/jest@v23.0.0...3a3b4e3) ##### Chore & Maintenance * `[jest-jasemine2]` Add dependency on jest-each ([#6308](`jestjs/jest#6308)) * `[jest-each]` Move jest-each into core Jest ([#6278](`jestjs/jest#6278)) * `[examples]` Update typescript example to using ts-jest ([#6260](`jestjs/jest#6260)) ##### Fixes * `[pretty-format]` Serialize inverse asymmetric matchers correctly ([#6272](`jestjs/jest#6272)) --- ### [`v23.0.0`](https://github.com/facebook/jest/blob/master/CHANGELOG.md#2300) [Compare Source](jestjs/jest@2745e3e...v23.0.0) ##### Features * `[expect]` Expose `getObjectSubset`, `iterableEquality`, and `subsetEquality` ([#6210](`jestjs/jest#6210)) * `[jest-snapshot]` Add snapshot property matchers ([#6210](`jestjs/jest#6210)) * `[jest-config]` Support jest-preset.js files within Node modules ([#6185](`jestjs/jest#6185)) * `[jest-cli]` Add `--detectOpenHandles` flag which enables Jest to potentially track down handles keeping it open after tests are complete. ([#6130](`jestjs/jest#6130)) * `[jest-jasmine2]` Add data driven testing based on `jest-each` ([#6102](`jestjs/jest#6102)) * `[jest-matcher-utils]` Change "suggest to equal" message to be more advisory ([#6103](`jestjs/jest#6103)) * `[jest-message-util]` Don't ignore messages with `vendor` anymore ([#6117](`jestjs/jest#6117)) * `[jest-validate]` Get rid of `jest-config` dependency ([#6067](`jestjs/jest#6067)) * `[jest-validate]` Adds option to inject `deprecationEntries` ([#6067](`jestjs/jest#6067)) * `[jest-snapshot]` [**BREAKING**] Concatenate name of test, optional snapshot name and count ([#6015](`jestjs/jest#6015)) * `[jest-runtime]` Allow for transform plugins to skip the definition process method if createTransformer method was defined. ([#5999](`jestjs/jest#5999)) * `[expect]` Add stack trace for async errors ([#6008](`jestjs/jest#6008)) * `[jest-jasmine2]` Add stack trace for timeouts ([#6008](`jestjs/jest#6008)) * `[jest-jasmine2]` Add stack trace for thrown non-`Error`s ([#6008](`jestjs/jest#6008)) * `[jest-runtime]` Prevent modules from marking themselves as their own parent ([#5235](`jestjs/jest#5235)) * `[jest-mock]` Add support for auto-mocking generator functions ([#5983](`jestjs/jest#5983)) * `[expect]` Add support for async matchers ([#5919](`jestjs/jest#5919)) * `[expect]` Suggest toContainEqual ([#5948](`jestjs/jest#5953)) * `[jest-config]` Export Jest's default options ([#5948](`jestjs/jest#5948)) * `[jest-editor-support]` Move `coverage` to `ProjectWorkspace.collectCoverage` ([#5929](`jestjs/jest#5929)) * `[jest-editor-support]` Add `coverage` option to runner ([#5836](`jestjs/jest#5836)) * `[jest-haste-map]` Support extracting dynamic `import`s ([#5883](`jestjs/jest#5883)) * `[expect]` Improve output format for mismatchedArgs in mock/spy calls. ([#5846](`jestjs/jest#5846)) * `[jest-cli]` Add support for using `--coverage` in combination with watch mode, `--onlyChanged`, `--findRelatedTests` and more ([#5601](`jestjs/jest#5601)) * `[jest-jasmine2]` [**BREAKING**] Adds error throwing and descriptive errors to `it`/ `test` for invalid arguments. `[jest-circus]` Adds error throwing and descriptive errors to `it`/ `test` for invalid arguments ([#5558](`jestjs/jest#5558)) * `[jest-matcher-utils]` Add `isNot` option to `matcherHint` function ([#5512](`jestjs/jest#5512)) * `[jest-config]` Add `<rootDir>` to runtime files not found error report ([#5693](`jestjs/jest#5693)) * `[expect]` Make toThrow matcher pass only if Error object is returned from promises ([#5670](`jestjs/jest#5670)) * `[expect]` Add isError to utils ([#5670](`jestjs/jest#5670)) * `[expect]` Add inverse matchers (`expect.not.arrayContaining`, etc., [#5517](`jestjs/jest#5517)) * `[expect]` `expect.extend` now also extends asymmetric matchers ([#5503](`jestjs/jest#5503)) * `[jest-mock]` Update `spyOnProperty` to support spying on the prototype chain ([#5753](`jestjs/jest#5753)) * `[jest-mock]` Add tracking of return values in the `mock` property ([#5752](`jestjs/jest#5752)) * `[jest-mock]` Add tracking of thrown errors in the `mock` property ([#5764](`jestjs/jest#5764)) * `[expect]`Add nthCalledWith spy matcher ([#5605](`jestjs/jest#5605)) * `[jest-cli]` Add `isSerial` property that runners can expose to specify that they can not run in parallel ([#5706](`jestjs/jest#5706)) * `[expect]` Add `.toBeCalledTimes` and `toHaveBeenNthCalledWith` aliases ([#5826](`jestjs/jest#5826)) * `[jest-cli]` Interactive Snapshot Mode improvements ([#5864](`jestjs/jest#5864)) * `[jest-editor-support]` Add `no-color` option to runner ([#5909](`jestjs/jest#5909)) * `[jest-jasmine2]` Pretty-print non-Error object errors ([#5980](`jestjs/jest#5980)) * `[jest-message-util]` Include column in stack frames ([#5889](`jestjs/jest#5889)) * `[expect]` Introduce toStrictEqual ([#6032](`jestjs/jest#6032)) * `[expect]` Add return matchers ([#5879](`jestjs/jest#5879)) * `[jest-cli]` Improve snapshot summaries ([#6181](`jestjs/jest#6181)) * `[expect]` Include custom mock names in error messages ([#6199](`jestjs/jest#6199)) * `[jest-diff]` Support returning diff from oneline strings ([#6221](`jestjs/jest#6221)) * `[expect]` Improve return matchers ([#6172](`jestjs/jest#6172)) * `[jest-cli]` Overhaul watch plugin hooks names ([#6249](`jestjs/jest#6249)) * `[jest-mock]` Include tracked call results in serialized mock ([#6244](`jestjs/jest#6244)) ##### Fixes * `[jest-cli]` Fix stdin encoding to utf8 for watch plugins. ([#6253](`jestjs/jest#6253)) * `[expect]` Better detection of DOM Nodes for equality ([#6246](`jestjs/jest#6246)) * `[jest-cli]` Fix misleading action description for F key when in "only failed tests" mode. ([#6167](`jestjs/jest#6167)) * `[jest-worker]` Stick calls to workers before processing them ([#6073](`jestjs/jest#6073)) * `[babel-plugin-jest-hoist]` Allow using `console` global variable ([#6075](`jestjs/jest#6075)) * `[jest-jasmine2]` Always remove node core message from assert stack traces ([#6055](`jestjs/jest#6055)) * `[expect]` Add stack trace when `expect.assertions` and `expect.hasAssertions` causes test failures. ([#5997](`jestjs/jest#5997)) * `[jest-runtime]` Throw a more useful error when trying to require modules after the test environment is torn down ([#5888](`jestjs/jest#5888)) * `[jest-mock]` [**BREAKING**] Replace timestamps with `invocationCallOrder` ([#5867](`jestjs/jest#5867)) * `[jest-jasmine2]` Install `sourcemap-support` into normal runtime to catch runtime errors ([#5945](`jestjs/jest#5945)) * `[jest-jasmine2]` Added assertion error handling inside `afterAll hook` ([#5884](`jestjs/jest#5884)) * `[jest-cli]` Remove the notifier actions in case of failure when not in watch mode. ([#5861](`jestjs/jest#5861)) * `[jest-mock]` Extend .toHaveBeenCalled return message with outcome ([#5951](`jestjs/jest#5951)) * `[jest-runner]` Assign `process.env.JEST_WORKER_ID="1"` when in runInBand mode ([#5860](`jestjs/jest#5860)) * `[jest-cli]` Add descriptive error message when trying to use `globalSetup`/`globalTeardown` file that doesn't export a function. ([#5835](`jestjs/jest#5835)) * `[expect]` Do not rely on `instanceof RegExp`, since it will not work for RegExps created inside of a different VM ([#5729](`jestjs/jest#5729)) * `[jest-resolve]` Update node module resolution algorithm to correctly handle symlinked paths ([#5085](`jestjs/jest#5085)) * `[jest-editor-support]` Update `Settings` to use spawn in shell option ([#5658](`jestjs/jest#5658)) * `[jest-cli]` Improve the error message when 2 projects resolve to the same config ([#5674](`jestjs/jest#5674)) * `[jest-runtime]` remove retainLines from coverage instrumentation ([#5692](`jestjs/jest#5692)) * `[jest-cli]` Fix update snapshot issue when using watchAll ([#5696](`jestjs/jest#5696)) * `[expect]` Fix rejects.not matcher ([#5670](`jestjs/jest#5670)) * `[jest-runtime]` Prevent Babel warnings on large files ([#5702](`jestjs/jest#5702)) * `[jest-mock]` Prevent `mockRejectedValue` from causing unhandled rejection ([#5720](`jestjs/jest#5720)) * `[pretty-format]` Handle React fragments better ([#5816](`jestjs/jest#5816)) * `[pretty-format]` Handle formatting of `React.forwardRef` and `Context` components ([#6093](`jestjs/jest#6093)) * `[jest-cli]` Switch collectCoverageFrom back to a string ([#5914](`jestjs/jest#5914)) * `[jest-regex-util]` Fix handling regex symbols in tests path on Windows ([#5941](`jestjs/jest#5941)) * `[jest-util]` Fix handling of NaN/Infinity in mock timer delay ([#5966](`jestjs/jest#5966)) * `[jest-resolve]` Generalise test for package main entries equivalent to ".". ([#5968](`jestjs/jest#5968)) * `[jest-config]` Ensure that custom resolvers are used when resolving the configuration ([#5976](`jestjs/jest#5976)) * `[website]` Fix website docs ([#5853](`jestjs/jest#5853)) * `[expect]` Fix isEqual Set and Map to compare object values and keys regardless of order ([#6150](`jestjs/jest#6150)) * `[pretty-format]` [**BREAKING**] Remove undefined props from React elements ([#6162](`jestjs/jest#6162)) * `[jest-haste-map]` Properly resolve mocked node modules without package.json defined ([#6232](`jestjs/jest#6232)) ##### Chore & Maintenance * `[jest-runner]` Move sourcemap installation from `jest-jasmine2` to `jest-runner` ([#6176](`jestjs/jest#6176)) * `[jest-cli]` Use yargs's built-in `version` instead of rolling our own ([#6215](`jestjs/jest#6215)) * `[docs]` Add explanation on how to mock methods not implemented in JSDOM * `[jest-jasmine2]` Simplify `Env.execute` and TreeProcessor to setup and clean resources for the top suite the same way as for all of the children suites ([#5885](`jestjs/jest#5885)) * `[babel-jest]` [**BREAKING**] Always return object from transformer ([#5991](`jestjs/jest#5991)) * `[*]` Run Prettier on compiled output ([#5858](`jestjs/jest#3497)) * `[jest-cli]` Add fileChange hook for plugins ([#5708](`jestjs/jest#5708)) * `[docs]` Add docs on using `jest.mock(...)` ([#5648](`jestjs/jest#5648)) * `[docs]` Mention Jest Puppeteer Preset ([#5722](`jestjs/jest#5722)) * `[docs]` Add jest-community section to website ([#5675](`jestjs/jest#5675)) * `[docs]` Add versioned docs for v22.4 ([#5733](`jestjs/jest#5733)) * `[docs]` Improve Snapshot Testing Guide ([#5812](`jestjs/jest#5812)) * `[jest-runtime]` [**BREAKING**] Remove `jest.genMockFn` and `jest.genMockFunction` ([#6173](`jestjs/jest#6173)) * `[jest-message-util]` Avoid adding unnecessary indent to blank lines in stack traces ([#6211](`jestjs/jest#6211)) --- ### [`v22.4.4`](jestjs/jest@6851d8b...v22.4.4) [Compare Source](jestjs/jest@6851d8b...v22.4.4) --- </details> --- This PR has been generated by [Renovate Bot](https://renovatebot.com).

github-actions · 2021-05-12T18:15:24Z

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SimenB mentioned this pull request Feb 24, 2018

use prettylint for markdown #5651

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danawoodman force-pushed the patch-1 branch from fafee8e to a8f9b79 Compare February 27, 2018 21:39

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danawoodman added 3 commits March 1, 2018 13:47

Update based on PR feedback

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Link markdown.

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Fix example code to actually run 🤦‍♂️

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danawoodman force-pushed the patch-1 branch from a8f9b79 to 1d63239 Compare March 1, 2018 22:03

Ugh missing ) 🤦‍♂️

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Use "mockResolvedValue" instead"

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rickhanlonii approved these changes Mar 1, 2018

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rickhanlonii merged commit aef82a2 into jestjs:master Mar 1, 2018

Update CHANGELOG.md

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ncovercash mentioned this pull request May 24, 2018

Update babel-jest to the latest version 🚀 Shopify/draggable#223

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Update babel-jest in / from 22.1.0 to 23.0.1 leonardofaria/leozera-ui#192

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Update jest in / from 22.1.4 to 23.6.0 leonardofaria/leozera-ui#250

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[Snyk] Upgrade expect from 23.0.0 to 23.6.0 yowainwright/react-workshop#8

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Add some docs on using `jest.mock(...)` #5648

Add some docs on using `jest.mock(...)` #5648

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		Now, in order to test this method without actually hitting the API (and thus creating slow and fragile tests), we can use the `jest.mock(...)` function to automatically mock the axios module.

		Once we mock the module we can spy on the `.get` method and provide a `mockImplementation` that returns the data we want our test to assert against. In effect, we are saying that we want axios.get('/users.json') to return a fake response.

Add some docs on using jest.mock(...) #5648

Add some docs on using jest.mock(...) #5648

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danawoodman commented Feb 23, 2018

Summary

Test plan

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Codecov Report

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Add some docs on using `jest.mock(...)` #5648

Add some docs on using `jest.mock(...)` #5648

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