7846/use property initializer syntax

CHANGELOG.md

@@ -14,6 +14,7 @@
 ### Chore & Maintenance
 
 - `[*]` Make sure to include `d.ts` files in the tarball when building ([#8086](https://github.com/facebook/jest/pull/8086))
+- `[*]` Use property initializer syntax in Jest codebase [#8117](https://github.com/facebook/jest/pull/8117)
 
 ### Performance
 

babel.config.js

@@ -21,6 +21,7 @@ module.exports = {
   plugins: [
     ['@babel/plugin-transform-modules-commonjs', {allowTopLevelThis: true}],
     '@babel/plugin-transform-strict-mode',
+    '@babel/plugin-proposal-class-properties',
   ],
   presets: [
     [

e2e/__tests__/__snapshots__/consoleAfterTeardown.test.ts.snap

@@ -15,6 +15,6 @@ PASS __tests__/console.test.js
       15 | });
       16 | 
 
-      at BufferedConsole.log (../../packages/jest-console/build/BufferedConsole.js:180:10)
+      at BufferedConsole.log (../../packages/jest-console/build/BufferedConsole.js:199:10)
       at log (__tests__/console.test.js:13:13)
 `;

e2e/__tests__/__snapshots__/detectOpenHandles.ts.snap

@@ -13,7 +13,13 @@ This usually means that there are asynchronous operations that weren't stopped i
 `;
 
 exports[`prints out info about open handlers 1`] = `
-Jest has detected the following 1 open handle potentially keeping Jest from exiting:
+Jest has detected the following 2 open handles potentially keeping Jest from exiting:
+
+  ●  DNSCHANNEL
+
+      at dns.js:333:23
+      at Object.listen (server.js:9:5)
+
 
   ●  GETADDRINFOREQWRAP
 

e2e/__tests__/__snapshots__/moduleNameMapper.test.ts.snap

@@ -30,6 +30,6 @@ FAIL __tests__/index.js
       12 | module.exports = () => 'test';
       13 | 
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:435:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:455:17)
       at Object.require (index.js:10:1)
 `;

e2e/__tests__/__snapshots__/resolveNoFileExtensions.test.ts.snap

@@ -33,6 +33,6 @@ FAIL __tests__/test.js
         |                  ^
       4 | 
 
-      at Resolver.resolveModule (../../packages/jest-resolve/build/index.js:202:17)
+      at Resolver.resolveModule (../../packages/jest-resolve/build/index.js:222:17)
       at Object.require (index.js:3:18)
 `;

examples/enzyme/.babelrc.js

@@ -2,4 +2,5 @@
 
 module.exports = {
   presets: ['@babel/preset-env', '@babel/preset-react'],
+  plugins: ['@babel/plugin-proposal-class-properties']
 };

examples/enzyme/CheckboxWithLabel.js

@@ -3,18 +3,13 @@
 import React from 'react';
 
 export default class CheckboxWithLabel extends React.Component {
-  constructor(props) {
-    super(props);
-    this.state = {isChecked: false};
+  state = {
+    isChecked: false,
+  };
 
-    // bind manually because React class components don't auto-bind
-    // http://facebook.github.io/react/blog/2015/01/27/react-v0.13.0-beta-1.html#autobinding
-    this.onChange = this.onChange.bind(this);
-  }
-
-  onChange() {
+  onChange = () => {
     this.setState({isChecked: !this.state.isChecked});
-  }
+  };
 
   render() {
     return (

examples/enzyme/package.json

@@ -8,6 +8,7 @@
   },
   "devDependencies": {
     "@babel/core": "*",
+    "@babel/plugin-proposal-class-properties": "*",
     "@babel/preset-env": "*",
     "@babel/preset-react": "*",
     "babel-jest": "*",

examples/react-testing-library/CheckboxWithLabel.js

@@ -6,15 +6,11 @@ export default class CheckboxWithLabel extends React.Component {
   constructor(props) {
     super(props);
     this.state = {isChecked: false};
-
-    // bind manually because React class components don't auto-bind
-    // http://facebook.github.io/react/blog/2015/01/27/react-v0.13.0-beta-1.html#autobinding
-    this.onChange = this.onChange.bind(this);
   }
 
-  onChange() {
+  onChange = () => {
     this.setState({isChecked: !this.state.isChecked});
-  }
+  };
 
   render() {
     return (

examples/react/CheckboxWithLabel.js

@@ -6,15 +6,11 @@ export default class CheckboxWithLabel extends React.Component {
   constructor(props) {
     super(props);
     this.state = {isChecked: false};
-
-    // bind manually because React class components don't auto-bind
-    // http://facebook.github.io/react/blog/2015/01/27/react-v0.13.0-beta-1.html#autobinding
-    this.onChange = this.onChange.bind(this);
   }
 
-  onChange() {
+  onChange = () => {
     this.setState({isChecked: !this.state.isChecked});
-  }
+  };
 
   render() {
     return (

examples/snapshot/.babelrc.js

@@ -2,4 +2,5 @@
 
 module.exports = {
   presets: ['@babel/preset-env', '@babel/preset-react'],
+  plugins: ['@babel/plugin-proposal-class-properties']
 };

examples/snapshot/Clock.react.js

@@ -3,11 +3,7 @@
 import React from 'react';
 
 export default class Clock extends React.Component {
-  constructor() {
-    super();
-
-    this.state = {seconds: Date.now() / 1000};
-  }
+  state = {seconds: Date.now() / 1000};
 
   componentDidMount() {
     this.timerID = setInterval(() => this.tick(), 1000);

examples/snapshot/Link.react.js

@@ -8,24 +8,17 @@ const STATUS = {
 };
 
 export default class Link extends React.Component {
-  constructor() {
-    super();
+  state = {
+    class: STATUS.NORMAL,
+  };
 
-    this._onMouseEnter = this._onMouseEnter.bind(this);
-    this._onMouseLeave = this._onMouseLeave.bind(this);
-
-    this.state = {
-      class: STATUS.NORMAL,
-    };
-  }
-
-  _onMouseEnter() {
+  _onMouseEnter = () => {
     this.setState({class: STATUS.HOVERED});
-  }
+  };
 
-  _onMouseLeave() {
+  _onMouseLeave = () => {
     this.setState({class: STATUS.NORMAL});
-  }
+  };
 
   render() {
     return (

examples/snapshot/package.json

@@ -7,6 +7,7 @@
   },
   "devDependencies": {
     "@babel/core": "*",
+    "@babel/plugin-proposal-class-properties": "*",
     "@babel/preset-env": "*",
     "@babel/preset-react": "*",
     "babel-jest": "*",

package.json

@@ -2,6 +2,7 @@
   "private": true,
   "devDependencies": {
     "@babel/core": "^7.3.4",
+    "@babel/plugin-proposal-class-properties": "^7.3.4",
     "@babel/plugin-transform-modules-commonjs": "^7.1.0",
     "@babel/plugin-transform-strict-mode": "^7.0.0",
     "@babel/preset-env": "^7.1.0",

packages/expect/src/__tests__/__snapshots__/spyMatchers.test.js.snap

@@ -247,7 +247,7 @@ But the last call returned:
   <red>\\"foo\\"</>"
 `;
 
-exports[`lastReturnedWith works with three calls 1`] = `
+exports[`lastReturnedWith works with three calls (3rd) 1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.lastReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function to not have last returned:
@@ -426,23 +426,23 @@ Expected mock function \\"named-mock\\" first call to have returned with:
 But it was <red>not called</>"
 `;
 
-exports[`nthReturnedWith incomplete recursive calls are handled properly 1`] = `
+exports[`nthReturnedWith incomplete recursive calls are handled properly  1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).nthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function first call to have returned with:
   <green>6</>
 But the first call <red>has not returned yet</>"
 `;
 
-exports[`nthReturnedWith incomplete recursive calls are handled properly 2`] = `
+exports[`nthReturnedWith incomplete recursive calls are handled properly  2`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).nthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function second call to have returned with:
   <green>3</>
 But the second call <red>has not returned yet</>"
 `;
 
-exports[`nthReturnedWith incomplete recursive calls are handled properly 3`] = `
+exports[`nthReturnedWith incomplete recursive calls are handled properly  3`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.nthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function third call to not have returned with:
@@ -451,7 +451,7 @@ But the third call returned exactly:
   <red>1</>"
 `;
 
-exports[`nthReturnedWith incomplete recursive calls are handled properly 4`] = `
+exports[`nthReturnedWith incomplete recursive calls are handled properly  4`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.nthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function 4th call to not have returned with:
@@ -1625,7 +1625,7 @@ But the last call returned:
   <red>\\"foo\\"</>"
 `;
 
-exports[`toHaveLastReturnedWith works with three calls 1`] = `
+exports[`toHaveLastReturnedWith works with three calls (3rd) 1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.toHaveLastReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function to not have last returned:
@@ -1667,23 +1667,23 @@ Expected mock function \\"named-mock\\" first call to have returned with:
 But it was <red>not called</>"
 `;
 
-exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly 1`] = `
+exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly  1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).toHaveNthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function first call to have returned with:
   <green>6</>
 But the first call <red>has not returned yet</>"
 `;
 
-exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly 2`] = `
+exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly  2`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).toHaveNthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function second call to have returned with:
   <green>3</>
 But the second call <red>has not returned yet</>"
 `;
 
-exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly 3`] = `
+exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly  3`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.toHaveNthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function third call to not have returned with:
@@ -1692,7 +1692,7 @@ But the third call returned exactly:
   <red>1</>"
 `;
 
-exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly 4`] = `
+exports[`toHaveNthReturnedWith incomplete recursive calls are handled properly  4`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.toHaveNthReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function 4th call to not have returned with:
@@ -2009,7 +2009,7 @@ exports[`toHaveReturnedTimes includes the custom mock name in the error message
 Expected mock function \\"named-mock\\" to have returned <green>one time</>, but it returned <red>two times</>."
 `;
 
-exports[`toHaveReturnedTimes incomplete recursive calls are handled properly 1`] = `
+exports[`toHaveReturnedTimes incomplete recursive calls are handled properly (2nd) 1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.toHaveReturnedTimes(</><green>2</><dim>)</>
 
 Expected mock function not to have returned <green>two times</>, but it returned exactly <red>two times</>."
@@ -2108,7 +2108,7 @@ Expected mock function \\"named-mock\\" to have returned:
 But it did <red>not return</>."
 `;
 
-exports[`toHaveReturnedWith incomplete recursive calls are handled properly 1`] = `
+exports[`toHaveReturnedWith incomplete recursive calls are handled properly (3rd) 1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).toHaveReturnedWith(</><green>expected</><dim>)</>
 
 Expected mock function to have returned:
@@ -2404,7 +2404,7 @@ exports[`toReturnTimes includes the custom mock name in the error message 1`] =
 Expected mock function \\"named-mock\\" to have returned <green>one time</>, but it returned <red>two times</>."
 `;
 
-exports[`toReturnTimes incomplete recursive calls are handled properly 1`] = `
+exports[`toReturnTimes incomplete recursive calls are handled properly (2nd) 1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).not.toReturnTimes(</><green>2</><dim>)</>
 
 Expected mock function not to have returned <green>two times</>, but it returned exactly <red>two times</>."
@@ -2503,7 +2503,7 @@ Expected mock function \\"named-mock\\" to have returned:
 But it did <red>not return</>."
 `;
 
-exports[`toReturnWith incomplete recursive calls are handled properly 1`] = `
+exports[`toReturnWith incomplete recursive calls are handled properly (3rd) 1`] = `
 "<dim>expect(</><red>jest.fn()</><dim>).toReturnWith(</><green>expected</><dim>)</>
 
 Expected mock function to have returned:

packages/expect/src/__tests__/spyMatchers.test.js

@@ -661,7 +661,7 @@ const jestExpect = require('../');
       ).toThrowErrorMatchingSnapshot();
     });
 
-    test(`incomplete recursive calls are handled properly`, () => {
+    test(`incomplete recursive calls are handled properly (2nd)`, () => {
       // sums up all integers from 0 -> value, using recursion
       const fn = jest.fn(value => {
         if (value === 0) {
@@ -892,7 +892,7 @@ const jestExpect = require('../');
         }).toThrowErrorMatchingSnapshot();
       });
 
-      test(`incomplete recursive calls are handled properly`, () => {
+      test(`incomplete recursive calls are handled properly (3rd)`, () => {
         // sums up all integers from 0 -> value, using recursion
         const fn = jest.fn(value => {
           if (value === 0) {
@@ -988,7 +988,7 @@ const jestExpect = require('../');
         }).toThrowErrorMatchingSnapshot();
       });
 
-      test(`incomplete recursive calls are handled properly`, () => {
+      test(`incomplete recursive calls are handled properly `, () => {
         // sums up all integers from 0 -> value, using recursion
         const fn = jest.fn(value => {
           if (value === 0) {
@@ -1027,7 +1027,7 @@ const jestExpect = require('../');
 
     const lastReturnedWith = ['toHaveLastReturnedWith', 'lastReturnedWith'];
     if (lastReturnedWith.indexOf(returnedWith) >= 0) {
-      test(`works with three calls`, () => {
+      test(`works with three calls (3rd)`, () => {
         const fn = jest.fn();
         fn.mockReturnValueOnce('foo1');
         fn.mockReturnValueOnce('foo2');

packages/jest-core/src/TestSequencer.ts

@@ -32,11 +32,7 @@ type Cache = {
  * is called to store/update this information on the cache map.
  */
 export default class TestSequencer {
-  private _cache: Map<Context, Cache>;
-
-  constructor() {
-    this._cache = new Map();
-  }
+  private _cache: Map<Context, Cache> = new Map();
 
   _getCachePath(context: Context) {
     const {config} = context;

packages/jest-core/src/plugins/update_snapshots_interactive.ts

@@ -11,16 +11,11 @@ import {BaseWatchPlugin, JestHookSubscriber} from 'jest-watcher';
 import SnapshotInteractiveMode from '../SnapshotInteractiveMode';
 
 class UpdateSnapshotInteractivePlugin extends BaseWatchPlugin {
-  private _snapshotInteractiveMode: SnapshotInteractiveMode;
-  private _failedSnapshotTestAssertions: Array<AssertionLocation>;
-  isInternal: true;
-
-  constructor(options: {stdin: NodeJS.ReadStream; stdout: NodeJS.WriteStream}) {
-    super(options);
-    this._failedSnapshotTestAssertions = [];
-    this._snapshotInteractiveMode = new SnapshotInteractiveMode(this._stdout);
-    this.isInternal = true;
-  }
+  private _snapshotInteractiveMode: SnapshotInteractiveMode = new SnapshotInteractiveMode(
+    this._stdout,
+  );
+  private _failedSnapshotTestAssertions: Array<AssertionLocation> = [];
+  isInternal: true = true;
 
   getFailedSnapshotTestAssertions(
     testResults: AggregatedResult,