chore: extract FakeTimers into a separate package

CHANGELOG.md

@@ -59,6 +59,7 @@
 - `[jest-phabricator]`: Migrate to TypeScript ([#7965](https://github.com/facebook/jest/pull/7965))
 - `[jest-runner]`: Migrate to TypeScript ([#7968](https://github.com/facebook/jest/pull/7968))
 - `[jest-runtime]`: Migrate to TypeScript ([#7964](https://github.com/facebook/jest/pull/7964))
+- `[@jest/fake-timers]`: Extract FakeTimers class from `jest-util` into a new separate package ([#7987](https://github.com/facebook/jest/pull/7987))
 
 ### Performance
 

packages/jest-environment-jsdom/package.json

@@ -9,6 +9,7 @@
   "license": "MIT",
   "main": "build/index.js",
   "dependencies": {
+    "@jest/fake-timers": "^24.1.0",
     "jest-mock": "^24.0.0",
     "jest-util": "^24.0.0",
     "jsdom": "^11.5.1"

packages/jest-environment-jsdom/src/index.js

@@ -12,7 +12,8 @@ import type {EnvironmentContext} from 'types/Environment';
 import type {Global} from 'types/Global';
 import type {ModuleMocker} from 'jest-mock';
 
-import {FakeTimers, installCommonGlobals} from 'jest-util';
+import FakeTimers from '@jest/fake-timers';
+import {installCommonGlobals} from 'jest-util';
 import mock from 'jest-mock';
 import {JSDOM, VirtualConsole} from 'jsdom';
 

packages/jest-environment-node/package.json

@@ -9,6 +9,7 @@
   "license": "MIT",
   "main": "build/index.js",
   "dependencies": {
+    "@jest/fake-timers": "^24.1.0",
     "jest-mock": "^24.0.0",
     "jest-util": "^24.0.0"
   },

packages/jest-environment-node/src/index.js

@@ -13,7 +13,8 @@ import type {Global} from 'types/Global';
 import type {ModuleMocker} from 'jest-mock';
 
 import vm from 'vm';
-import {FakeTimers, installCommonGlobals} from 'jest-util';
+import FakeTimers from '@jest/fake-timers';
+import {installCommonGlobals} from 'jest-util';
 import mock from 'jest-mock';
 
 type Timer = {|

packages/jest-environment/package.json

@@ -10,6 +10,7 @@
   "main": "build/index.js",
   "types": "build/index.d.ts",
   "dependencies": {
+    "@jest/fake-timers": "^24.1.0",
     "@jest/transform": "^24.1.0",
     "@jest/types": "^24.1.0",
     "@types/node": "*",

packages/jest-environment/src/index.ts

@@ -7,8 +7,12 @@
 
 import {Script} from 'vm';
 import {Config, Global} from '@jest/types';
-import moduleMocker from 'jest-mock';
+import jestMock, {ModuleMocker} from 'jest-mock';
 import {ScriptTransformer} from '@jest/transform';
+import FakeTimers from '@jest/fake-timers';
+
+type JestMockFn = typeof jestMock.fn;
+type JestMockSpyOn = typeof jestMock.spyOn;
 
 export type EnvironmentContext = {
   console?: Console;
@@ -27,21 +31,10 @@ export interface JestEnvironment {
     script: Script,
   ): {[ScriptTransformer.EVAL_RESULT_VARIABLE]: ModuleWrapper} | null;
   global: Global.Global;
-  // TODO: When `jest-util` is ESM, this can just be `fakeTimers: import('jest-util').FakeTimers`
-  fakeTimers: {
-    clearAllTimers(): void;
-    runAllImmediates(): void;
-    runAllTicks(): void;
-    runAllTimers(): void;
-    advanceTimersByTime(msToRun: number): void;
-    runOnlyPendingTimers(): void;
-    runWithRealTimers(callback: () => void): void;
-    getTimerCount(): number;
-    useFakeTimers(): void;
-    useRealTimers(): void;
-  };
+  // TODO: This is nullable, and TS doesn't understand we deal with it in `jest-runtime`. Should be fixed
+  fakeTimers: FakeTimers<unknown>;
   testFilePath: Config.Path;
-  moduleMocker: typeof moduleMocker;
+  moduleMocker: ModuleMocker;
   setup(): Promise<void>;
   teardown(): Promise<void>;
 }
@@ -112,7 +105,7 @@ export interface Jest {
   /**
    * Creates a mock function. Optionally takes a mock implementation.
    */
-  fn: typeof moduleMocker.fn;
+  fn: JestMockFn;
   /**
    * Given the name of a module, use the automatic mocking system to generate a
    * mocked version of the module for you.
@@ -124,7 +117,7 @@ export interface Jest {
   /**
    * Determines if the given function is a mocked function.
    */
-  isMockFunction(fn: Function): fn is ReturnType<typeof moduleMocker.fn>;
+  isMockFunction(fn: Function): fn is ReturnType<JestMockFn>;
   /**
    * Mocks a module with an auto-mocked version when it is being required.
    */
@@ -235,7 +228,7 @@ export interface Jest {
    * Note: By default, jest.spyOn also calls the spied method. This is
    * different behavior from most other test libraries.
    */
-  spyOn: typeof moduleMocker.spyOn;
+  spyOn: JestMockSpyOn;
   /**
    * Indicates that the module system should never return a mocked version of
    * the specified module from require() (e.g. that it should always return the

packages/jest-environment/tsconfig.json

@@ -5,6 +5,7 @@
     "outDir": "build"
   },
   "references": [
+    {"path": "../jest-fake-timers"},
     {"path": "../jest-transform"},
     {"path": "../jest-types"},
     {"path": "../jest-util"}

packages/jest-fake-timers/.npmignore

@@ -0,0 +1,3 @@
+**/__mocks__/**
+**/__tests__/**
+src

packages/jest-fake-timers/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "@jest/fake-timers",
+  "version": "24.1.0",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/facebook/jest.git",
+    "directory": "packages/jest-fake-timers"
+  },
+  "license": "MIT",
+  "main": "build/index.js",
+  "types": "build/index.d.ts",
+  "dependencies": {
+    "@jest/types": "^24.1.0",
+    "@types/node": "*",
+    "jest-message-util": "^24.0.0",
+    "jest-mock": "^24.0.0"
+  },
+  "engines": {
+    "node": ">= 6"
+  },
+  "gitHead": "b16789230fd45056a7f2fa199bae06c7a1780deb"
+}

packages/jest-util/src/__tests__/fakeTimers.test.ts → packages/jest-fake-timers/src/__tests__/index.test.ts

@@ -7,9 +7,7 @@
 
 import vm from 'vm';
 import mock from 'jest-mock';
-import FakeTimers from '../FakeTimers';
-// TODO: import this type directly from jest-mock once TS migration is done
-type ModuleMocker = typeof mock;
+import FakeTimers from '../';
 
 const timerConfig = {
   idToRef: (id: number) => id,
@@ -22,7 +20,7 @@ const config = {
 };
 
 describe('FakeTimers', () => {
-  let moduleMocker: ModuleMocker;
+  let moduleMocker: mock.ModuleMocker;
 
   beforeEach(() => {
     const global = vm.runInNewContext('this');

packages/jest-util/src/FakeTimers.ts → packages/jest-fake-timers/src/index.ts

@@ -5,18 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import mock from 'jest-mock';
+import {ModuleMocker} from 'jest-mock';
 import {formatStackTrace, StackTraceConfig} from 'jest-message-util';
-import setGlobal from './setGlobal';
 
-type ModuleMocker = typeof mock;
-
-/**
- * We don't know the type of arguments for a callback ahead of time which is why
- * we are disabling the flowtype/no-weak-types rule here.
- */
-
-type Callback = (...args: any) => void;
+type Callback = (...args: Array<unknown>) => void;
 
 type TimerID = string;
 
@@ -50,6 +42,16 @@ type TimerConfig<Ref> = {
 
 const MS_IN_A_YEAR = 31536000000;
 
+// TODO: Copied from `jest-util` to avoid cyclic dependency. Import from `jest-util` in the next major
+const setGlobal = (
+  globalToMutate: NodeJS.Global | Window,
+  key: string,
+  value: unknown,
+) => {
+  // @ts-ignore: no index
+  globalToMutate[key] = value;
+};
+
 export default class FakeTimers<TimerRef> {
   private _cancelledImmediates!: {[key: string]: boolean};
   private _cancelledTicks!: {[key: string]: boolean};

packages/jest-fake-timers/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build"
+  },
+  "references": [
+    {"path": "../jest-message-util"},
+    {"path": "../jest-mock"}
+  ]
+}

packages/jest-util/package.json

@@ -10,14 +10,13 @@
   "main": "build/index.js",
   "types": "build/index.d.ts",
   "dependencies": {
+    "@jest/fake-timers": "^24.1.0",
     "@jest/types": "^24.1.0",
     "@types/node": "*",
     "callsites": "^3.0.0",
     "chalk": "^2.0.1",
     "graceful-fs": "^4.1.15",
     "is-ci": "^2.0.0",
-    "jest-message-util": "^24.0.0",
-    "jest-mock": "^24.0.0",
     "mkdirp": "^0.5.1",
     "readable-stream": "^3.1.1",
     "slash": "^2.0.0",

packages/jest-util/src/index.ts

@@ -5,12 +5,13 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+// TODO: Remove this export in the next major
+import FakeTimers from '@jest/fake-timers';
 import BufferedConsole from './BufferedConsole';
 import clearLine from './clearLine';
 import CustomConsole from './CustomConsole';
 import createDirectory from './createDirectory';
 import ErrorWithStack from './ErrorWithStack';
-import FakeTimers from './FakeTimers';
 import formatTestResults from './formatTestResults';
 import getFailedSnapshotTests from './getFailedSnapshotTests';
 import getConsoleOutput from './getConsoleOutput';

packages/jest-util/tsconfig.json

@@ -5,8 +5,7 @@
     "outDir": "build"
   },
   "references": [
-    {"path": "../jest-types"},
-    {"path": "../jest-message-util"},
-    {"path": "../jest-mock"}
+    {"path": "../jest-fake-timers"},
+    {"path": "../jest-types"}
   ]
 }