[WIP] Upgrade entire suite to Babel 7

.flowconfig

@@ -18,4 +18,4 @@ untyped-import
 untyped-type-import
 
 [version]
-^0.75.0
+^0.80.0

.vscode/launch.json

@@ -9,7 +9,8 @@
       "request": "launch",
       "name": "Debug Jest with current test file",
       "program": "${workspaceFolder}/packages/jest-cli/bin/jest.js",
-      "args": ["--runInBand", "${file}"]
+      "args": ["--runInBand", "${file}"],
+      "runtimeArgs": ["-r", "flow-remove-types/register"]
     }
   ]
 }

CHANGELOG.md

@@ -1,14 +1,33 @@
 ## master
 
+### Features
+
+- `[pretty-format]` Option to not escape strings in diff messages ([#5661](https://github.com/facebook/jest/pull/5661))
+- `[jest-haste-map]` Add `getFileIterator` to `HasteFS` for faster file iteration ([#7010](https://github.com/facebook/jest/pull/7010)).
+
 ### Fixes
 
-- `[jest-haste-map]` [**BREAKING**] Replaced internal data structures to improve performance ([#6960](https://github.com/facebook/jest/pull/6960))
+- `[jest-haste-map]` [**BREAKING**] Replace internal data structures to improve performance ([#6960](https://github.com/facebook/jest/pull/6960))
+- `[jest-haste-map]` Do not visit again files with the same sha-1 ([#6990](https://github.com/facebook/jest/pull/6990))
+- `[jest-jasmine2]` Fix memory leak in Error objects hold by the framework ([#6965](https://github.com/facebook/jest/pull/6965))
+- `[jest-haste-map]` Fixed Haste whitelist generation for scoped modules on Windows ([#6980](https://github.com/facebook/jest/pull/6980))
+- `[jest-mock]` Fix inheritance of static properties and methods in mocks ([#7003](https://github.com/facebook/jest/pull/7003))
+- `[jest-mock]` Fix mocking objects without `Object.prototype` in their prototype chain ([#7003](https://github.com/facebook/jest/pull/7003))
+
+### Chore & Maintenance
+
+- `[docs]` Fix babel-core installation instructions ([#6745](https://github.com/facebook/jest/pull/6745))
+- `[docs]` Explain how to rewrite assertions to avoid large irrelevant diff ([#6971](https://github.com/facebook/jest/pull/6971))
+- `[examples]` add example using Babel 7 ([#6983](https://github.com/facebook/jest/pull/6983))
+- `[docs]` Replace shallow equality with referential identity in `ExpectAPI.md` ([#6991](https://github.com/facebook/jest/pull/6991))
+- `[jest-changed-files]` Refactor to use `execa` over `child_process` ([#6987](https://github.com/facebook/jest/pull/6987))
+- `[*]` Bump dated dependencies ([#6978](https://github.com/facebook/jest/pull/6978))
 
 ## 23.6.0
 
 ### Features
 
-- `[jest-ci]` Add `changedSince` to allowed watch mode configs ([#6955](https://github.com/facebook/jest/pull/6955))
+- `[jest-cli]` Add `changedSince` to allowed watch mode configs ([#6955](https://github.com/facebook/jest/pull/6955))
 - `[babel-jest]` Add support for `babel.config.js` added in Babel 7.0.0 ([#6911](https://github.com/facebook/jest/pull/6911))
 
 ### Fixes

CONTRIBUTING.md

@@ -24,10 +24,10 @@ _Before_ submitting a pull request, please make sure the following is done…
 
     Open terminal (e.g. Terminal, iTerm, Git Bash or Git Shell) and type:
 
-    ```sh
-    git clone https://github.com/<your_username>/jest
-    cd jest
-    git checkout -b my_branch
+    ```sh-session
+    $ git clone https://github.com/<your_username>/jest
+    $ cd jest
+    $ git checkout -b my_branch
     ```
 
     Note: Replace `<your_username>` with your GitHub username
@@ -37,7 +37,8 @@ _Before_ submitting a pull request, please make sure the following is done…
 1.  Make sure you have `python` installed (v2.7 is recommended, v3.x.x is not supported). Python is required by [node-gyp](https://github.com/nodejs/node-gyp) that is used when running `yarn install`.
 
     To check your version of Python and ensure it's installed you can type:
-    ```
+
+    ```sh
     python --version
     ```
 
@@ -64,9 +65,9 @@ _Before_ submitting a pull request, please make sure the following is done…
 
 1.  Ensure the test suite passes via `yarn test`. To run the test suite you may need to install [Mercurial](https://www.mercurial-scm.org/) (`hg`). On macOS, this can be done using [homebrew](http://brew.sh/): `brew install hg`.
 
-    ```sh
-    brew install hg # maybe
-    yarn test
+    ```sh-session
+    $ brew install hg # maybe
+    $ yarn test
     ```
 
 1.  If you haven't already, complete the CLA.
@@ -76,10 +77,10 @@ _Before_ submitting a pull request, please make sure the following is done…
 If you are making changes to the website or documentation, test the website folder and run the server to check if your changes are being displayed accurately.
 
 1.  Locate to the website directory and install any website specific dependencies by typing in `yarn`. Following steps are to be followed for this purpose from the root directory.
-    ```sh
-    cd website       # Only needed if you are not already in the website directory
-    yarn
-    yarn start
+    ```sh-session
+    $ cd website       # Only needed if you are not already in the website directory
+    $ yarn
+    $ yarn start
     ```
 1.  You can run a development server to check if the changes you made are being displayed accurately by running `yarn start` in the website directory.
 
@@ -93,34 +94,34 @@ In order to accept your pull request, we need you to submit a CLA. You only need
 
 To link `jest` on the command line to `jest-cli/bin/jest.js` in a development build:
 
-```sh
-cd /path/to/your/Jest_clone/packages/jest-cli
-yarn link
+```sh-session
+$ cd /path/to/your/Jest_clone/packages/jest-cli
+$ yarn link
 ```
 
 To build Jest:
 
-```sh
-cd /path/to/your/Jest_clone
+```sh-session
+$ cd /path/to/your/Jest_clone
 
 # Do one of the following:
 
 # Check out a commit from another contributor, and then
-yarn run build
+$ yarn run build
 
 # Or, save your changes to Jest, and then
-yarn test # which also builds Jest
+$ yarn test # which also builds Jest
 ```
 
 To run tests in another project with the development build of Jest:
 
-```sh
-cd /path/to/another/project
+```sh-session
+$ cd /path/to/another/project
 
 # link development build to the other project
-yarn link jest-cli
+$ yarn link jest-cli
 
-jest [options] # run jest-cli/bin/jest.js in the development build
+$ jest [options] # run jest-cli/bin/jest.js in the development build
 ```
 
 - To decide whether to specify any options, see `test` under `scripts` in the `package.json` file of the other project.

README.md

@@ -17,6 +17,7 @@
     <a href="#backers"><img src="https://opencollective.com/jest/backers/badge.svg" alt="Backers on Open Collective"></a>
     <a href="#sponsors"><img src="https://opencollective.com/jest/sponsors/badge.svg" alt="Sponsors on Open Collective"></a>
     <a href="https://opensource.org/licenses/MIT"><img src="https://img.shields.io/badge/License-MIT-yellow.svg" alt="License: MIT"></a>
+     <a href="https://snyk.io/test/github/facebook/jest?targetFile=packages/jest/package.json"><img src="https://snyk.io/test/github/facebook/jest/badge.svg?targetFile=packages/jest/package.json" alt="Known Vulnerabilities" data-canonical-src="https://snyk.io/test/github/facebook/jest?targetFile=packages/jest/package.json" style="max-width:100%;"></a>
 </p>
 
 **👩🏻‍💻 Developer Ready**: Complete and ready to set-up JavaScript testing solution. Works out of the box for any React project.
@@ -99,39 +100,22 @@ If you'd like to learn more about running `jest` through the command line, take
 
 ### Using Babel
 
-[Babel](http://babeljs.io/) is automatically handled by Jest using `babel-jest`. You don't need install anything extra for using Babel.
+To use [Babel](http://babeljs.io/), install the `babel-jest` and `@babel/core` packages:
 
-> Note: If you are using a babel version 7 then you need to install `babel-core@^7.0.0-0` and `@babel/core` with the following command:
->
-> ```bash
-> yarn add --dev 'babel-core@^7.0.0-0' @babel/core
-> ```
+```bash
+yarn add --dev babel-jest @babel/core
+```
 
-Don't forget to add a [`.babelrc`](https://babeljs.io/docs/usage/babelrc/) file in your project's root folder. For example, if you are using ES6 and [React.js](https://reactjs.org) with the [`babel-preset-env`](https://babeljs.io/docs/plugins/preset-env/) and [`babel-preset-react`](https://babeljs.io/docs/plugins/preset-react/) presets:
+Don't forget to add a [`babel.config.js`](https://babeljs.io/docs/en/config-files) file in your project's root folder. For example, if you are using ES6 and [React.js](https://reactjs.org) with the [`@babel/preset-env`](https://babeljs.io/docs/en/babel-preset-env) and [`@babel/preset-react`](https://babeljs.io/docs/en/babel-preset-react) presets:
 
-```json
-{
-  "presets": ["env", "react"]
-}
+```js
+module.exports = {
+  presets: ['@babel/preset-env', '@babel/preset-react'],
+};
 ```
 
 You are now set up to use all ES6 features and React specific syntax.
 
-> Note: If you are using a more complicated Babel configuration, using Babel's `env` option, keep in mind that Jest will automatically define `NODE_ENV` as `test`. It will not use `development` section like Babel does by default when no `NODE_ENV` is set.
-
-> Note: If you've turned off transpilation of ES modules with the option `{ "modules": false }`, you have to make sure to turn this on in your test environment.
-
-```json
-{
-  "presets": [["env", {"modules": false}], "react"],
-  "env": {
-    "test": {
-      "presets": [["env"], "react"]
-    }
-  }
-}
-```
-
 > Note: `babel-jest` is automatically installed when installing Jest and will automatically transform files if a babel configuration exists in your project. To avoid this behavior, you can explicitly reset the `transform` configuration option:
 
 ```json

babel.config.js

@@ -0,0 +1,22 @@
+module.exports = {
+  // babelrcRoots: ['.', 'packages/*', 'examples/*'],
+  plugins: [
+    // Required by some examples, like react-native. Without this plugin,
+    // they will simply crash before relative configs can be found.
+    // '@babel/plugin-proposal-class-properties',
+    ['@babel/plugin-transform-modules-commonjs', {allowTopLevelThis: true}],
+  ],
+  presets: [
+    [
+      '@babel/preset-env',
+      {
+        shippedProposals: true,
+        targets: {node: '6'},
+        useBuiltIns: 'usage',
+      },
+    ],
+    '@babel/preset-flow',
+    // Some tests contain JSX
+    '@babel/preset-react',
+  ],
+};

docs/Es6ClassMocks.md

@@ -227,7 +227,7 @@ jest.mock('./sound-player', () => {
 });
 ```
 
-This will throw **_TypeError: \_soundPlayer2.default is not a constructor_**, unless the code is transpiled to ES5, e.g. by babel-preset-env. (ES5 doesn't have arrow functions nor classes, so both will be transpiled to plain functions.)
+This will throw **_TypeError: \_soundPlayer2.default is not a constructor_**, unless the code is transpiled to ES5, e.g. by `@babel/preset-env`. (ES5 doesn't have arrow functions nor classes, so both will be transpiled to plain functions.)
 
 ## Keeping track of usage (spying on the mock)
 

docs/ExpectAPI.md

@@ -512,7 +512,7 @@ test('rejects to octopus', async () => {
 
 ### `.toBe(value)`
 
-`toBe` just checks that a value is what you expect. It uses `Object.is` to check exact equality.
+Use `.toBe` to compare primitive values or to check referential identity of object instances. It calls `Object.is` to compare values, which is even better for testing than `===` strict equality operator.
 
 For example, this code will validate some properties of the `can` object:
 
@@ -533,7 +533,12 @@ describe('the can', () => {
 });
 ```
 
-Don't use `toBe` with floating-point numbers. For example, due to rounding, in JavaScript `0.2 + 0.1` is not strictly equal to `0.3`. If you have floating point numbers, try `.toBeCloseTo` instead.
+Don't use `.toBe` with floating-point numbers. For example, due to rounding, in JavaScript `0.2 + 0.1` is not strictly equal to `0.3`. If you have floating point numbers, try `.toBeCloseTo` instead.
+
+Although the `.toBe` matcher **checks** referential identity, it **reports** a deep comparison of values if the assertion fails. If differences between properties do not help you to understand why a test fails, especially if the report is large, then you might move the comparison into the `expect` function. For example, to assert whether or not elements are the same instance:
+
+- rewrite `expect(received).toBe(expected)` as `expect(Object.is(received, expected)).toBe(true)`
+- rewrite `expect(received).not.toBe(expected)` as `expect(Object.is(received, expected)).toBe(false)`
 
 ### `.toHaveBeenCalled()`
 
@@ -906,7 +911,9 @@ describe('my beverage', () => {
 
 ### `.toEqual(value)`
 
-Use `.toEqual` when you want to check that two objects have the same value. This matcher recursively checks the equality of all fields, rather than checking for object identity—this is also known as "deep equal". For example, `toEqual` and `toBe` behave differently in this test suite, so all the tests pass:
+Use `.toEqual` to compare recursively all properties of object instances (also known as "deep" equality). It calls `Object.is` to compare primitive values, which is even better for testing than `===` strict equality operator.
+
+For example, `.toEqual` and `.toBe` behave differently in this test suite, so all the tests pass:
 
 ```js
 const can1 = {
@@ -930,6 +937,11 @@ describe('the La Croix cans on my desk', () => {
 
 > Note: `.toEqual` won't perform a _deep equality_ check for two errors. Only the `message` property of an Error is considered for equality. It is recommended to use the `.toThrow` matcher for testing against errors.
 
+If differences between properties do not help you to understand why a test fails, especially if the report is large, then you might move the comparison into the `expect` function. For example, use `equals` method of `Buffer` class to assert whether or not buffers contain the same content:
+
+- rewrite `expect(received).toEqual(expected)` as `expect(received.equals(expected)).toBe(true)`
+- rewrite `expect(received).not.toEqual(expected)` as `expect(received.equals(expected)).toBe(false)`
+
 ### `.toHaveLength(number)`
 
 Use `.toHaveLength` to check that an object has a `.length` property and it is set to a certain numeric value.

docs/GettingStarted.md

@@ -79,45 +79,22 @@ jest --init
 
 ### Using Babel
 
-To use [Babel](http://babeljs.io/), install the `babel-jest` and `regenerator-runtime` packages:
+To use [Babel](http://babeljs.io/), install the `babel-jest` and `@babel/core` packages:
 
 ```bash
-yarn add --dev babel-jest babel-core regenerator-runtime
+yarn add --dev babel-jest @babel/core
 ```
 
-> Note: If you are using a babel version 7 then you need to install `babel-jest` with the following command:
->
-> ```bash
-> yarn add --dev babel-jest 'babel-core@^7.0.0-0' @babel/core regenerator-runtime
-> ```
+Don't forget to add a [`babel.config.js`](https://babeljs.io/docs/en/config-files) file in your project's root folder. For example, if you are using ES6 and [React.js](https://reactjs.org) with the [`@babel/preset-env`](https://babeljs.io/docs/en/babel-preset-env) and [`@babel/preset-react`](https://babeljs.io/docs/en/babel-preset-react) presets:
 
-_Note: Explicitly installing `regenerator-runtime` is not needed if you use `npm` 3 or 4 or Yarn_
-
-Don't forget to add a [`.babelrc`](https://babeljs.io/docs/usage/babelrc/) file in your project's root folder. For example, if you are using ES6 and [React.js](https://facebook.github.io/react/) with the [`babel-preset-env`](https://babeljs.io/docs/plugins/preset-env/) and [`babel-preset-react`](https://babeljs.io/docs/plugins/preset-react/) presets:
-
-```json
-{
-  "presets": ["env", "react"]
-}
+```js
+module.exports = {
+  presets: ['@babel/preset-env', '@babel/preset-react'],
+};
 ```
 
 You are now set up to use all ES6 features and React specific syntax.
 
-> Note: If you are using a more complicated Babel configuration, using Babel's `env` option, keep in mind that Jest will automatically define `NODE_ENV` as `test`. It will not use `development` section like Babel does by default when no `NODE_ENV` is set.
-
-> Note: If you've turned off transpilation of ES6 modules with the option `{ "modules": false }`, you have to make sure to turn this on in your test environment.
-
-```json
-{
-  "presets": [["env", {"modules": false}], "react"],
-  "env": {
-    "test": {
-      "presets": [["env"], "react"]
-    }
-  }
-}
-```
-
 > Note: `babel-jest` is automatically installed when installing Jest and will automatically transform files if a babel configuration exists in your project. To avoid this behavior, you can explicitly reset the `transform` configuration option:
 
 ```json

docs/TestingAsyncCode.md

@@ -120,7 +120,7 @@ test('the data is peanut butter', async () => {
 
 test('the fetch fails with an error', async () => {
   expect.assertions(1);
-  await expect(fetchData()).rejects.toMatch('error');
+  await expect(fetchData()).rejects.toThrow('error');
 });
 ```
 

docs/Troubleshooting.md

@@ -132,7 +132,7 @@ If you are using Facebook's [`create-react-app`](https://github.com/facebookincu
 
 ## Caching Issues
 
-The transform script was changed or babel was updated and the changes aren't being recognized by Jest?
+The transform script was changed or Babel was updated and the changes aren't being recognized by Jest?
 
 Retry with [`--no-cache`](CLI.md#cache). Jest caches transformed module files to speed up test execution. If you are using your own custom transformer, consider adding a `getCacheKey` function to it: [getCacheKey in Relay](https://github.com/facebook/relay/blob/58cf36c73769690f0bbf90562707eadb062b029d/scripts/jest/preprocessor.js#L56-L61).
 

docs/TutorialAsync.md

@@ -109,7 +109,7 @@ it('works with async/await and resolves', async () => {
 });
 ```
 
-To enable async/await in your project, install [`babel-preset-env`](http://babeljs.io/docs/plugins/preset-env/) and enable the feature in your `.babelrc` file.
+To enable async/await in your project, install [`@babel/preset-env`](https://babeljs.io/docs/en/babel-preset-env) and enable the feature in your `babel.config.js` file.
 
 ## Error handling