add mock type utils to jest

packages/jest-globals/index.d.ts

@@ -0,0 +1,81 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import type {Jest} from '@jest/environment';
+import type {JestExpect} from '@jest/expect';
+import type {Global} from '@jest/types';
+
+export declare const jest: Jest;
+
+export declare const expect: JestExpect;
+
+export declare const test: Global.GlobalAdditions['test'];
+export declare const xtest: Global.GlobalAdditions['xtest'];
+
+export declare const it: Global.GlobalAdditions['it'];
+export declare const fit: Global.GlobalAdditions['fit'];
+export declare const xit: Global.GlobalAdditions['xit'];
+
+export declare const describe: Global.GlobalAdditions['describe'];
+export declare const fdescribe: Global.GlobalAdditions['fdescribe'];
+export declare const xdescribe: Global.GlobalAdditions['xdescribe'];
+
+export declare const beforeAll: Global.GlobalAdditions['beforeAll'];
+export declare const beforeEach: Global.GlobalAdditions['beforeEach'];
+
+export declare const afterEach: Global.GlobalAdditions['afterEach'];
+export declare const afterAll: Global.GlobalAdditions['afterAll'];
+
+declare namespace jest {
+  /**
+   * Wraps an object or a module with mock definitions.
+   *
+   * @example
+   *
+   *  jest.mock('../api');
+   *  import * as api from '../api';
+   *
+   *  const mockApi = api as jest.Mocked<typeof api>;
+   *
+   *  api.MyApi.prototype.myApiMethod.mockImplementation(() => 'test');
+   */
+  export type Mocked<T> = import('jest-mock').Mocked<T>;
+
+  /**
+   * Wraps a class with mock definitions.
+   *
+   * @example
+   *
+   *  import {MyClass} from './library';
+   *  jest.mock('./library');
+   *
+   *  const mockMyClass = MyClass as jest.MockedClass<typeof MyClass>;
+   *
+   *  expect(mockMyClass.mock.calls[0][0]).toBe(42); // Constructor calls
+   *  expect(mockMyClass.prototype.myMethod.mock.calls[0][0]).toBe(42); // Method calls
+   */
+  export type MockedClass<T> = import('jest-mock').MockedClass<T>;
+
+  /**
+   * Wraps a function with mock definitions.
+   *
+   * @example
+   *
+   *  import {myFunction} from './library';
+   *  jest.mock('./library');
+   *
+   *  const mockMyFunction = myFunction as jest.MockedFunction<typeof myFunction>;
+   *
+   *  expect(mockMyFunction.mock.calls[0][0]).toBe(42);
+   */
+  export type MockedFunction<T> = import('jest-mock').MockedFunction<T>;
+
+  /**
+   * Wraps a function with spy definitions.
+   */
+  export type SpiedFunction<T> = import('jest-mock').SpiedFunction<T>;
+}

packages/jest-globals/index.js

@@ -0,0 +1,11 @@
+'use strict';
+
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+throw new Error(
+  'Do not import `@jest/globals` outside of the Jest test environment'
+);

packages/jest-globals/package.json

@@ -10,19 +10,20 @@
     "node": "^12.13.0 || ^14.15.0 || ^16.13.0 || >=17.0.0"
   },
   "license": "MIT",
-  "main": "./build/index.js",
-  "types": "./build/index.d.ts",
+  "main": "./index.js",
+  "types": "./index.d.ts",
   "exports": {
     ".": {
-      "types": "./build/index.d.ts",
-      "default": "./build/index.js"
+      "types": "./index.d.ts",
+      "default": "./index.js"
     },
     "./package.json": "./package.json"
   },
   "dependencies": {
     "@jest/environment": "^28.0.0-alpha.3",
     "@jest/expect": "^28.0.0-alpha.3",
-    "@jest/types": "^28.0.0-alpha.3"
+    "@jest/types": "^28.0.0-alpha.3",
+    "jest-mock": "^28.0.0-alpha.3"
   },
   "publishConfig": {
     "access": "public"

packages/jest-globals/tsconfig.json

@@ -11,6 +11,7 @@
   "references": [
     {"path": "../jest-environment"},
     {"path": "../jest-expect"},
+    {"path": "../jest-mock"},
     {"path": "../jest-types"}
   ]
 }

packages/jest-mock/src/index.ts

@@ -78,23 +78,33 @@ export type MaybeMocked<T> = T extends MockableFunction
   ? MockedObject<T>
   : T;
 
-export type ArgsType<T> = T extends (...args: infer A) => any ? A : never;
+type ClassLike = {
+  new (...args: Array<unknown>): unknown;
+};
+
+type FunctionLike = {
+  (...args: Array<unknown>): unknown;
+};
+
 export type Mocked<T> = {
-  [P in keyof T]: T[P] extends (...args: Array<any>) => any
-    ? MockInstance<ReturnType<T[P]>, ArgsType<T[P]>>
-    : T[P] extends Constructable
+  [P in keyof T]: T[P] extends FunctionLike
+    ? MockInstance<ReturnType<T[P]>, Parameters<T[P]>>
+    : T[P] extends ClassLike
     ? MockedClass<T[P]>
     : T[P];
 } & T;
-export type MockedClass<T extends Constructable> = MockInstance<
+
+export type MockedClass<T extends ClassLike> = MockInstance<
   InstanceType<T>,
   T extends new (...args: infer P) => any ? P : never
 > & {
   prototype: T extends {prototype: any} ? Mocked<T['prototype']> : never;
 } & T;
-export interface Constructable {
-  new (...args: Array<any>): any;
-}
+
+export type SpiedFunction<T extends FunctionLike> = SpyInstance<
+  ReturnType<T>,
+  Parameters<T>
+>;
 
 export interface MockWithArgs<T extends MockableFunction>
   extends MockInstance<ReturnType<T>, ArgumentsOf<T>> {

packages/jest-types/__typetests__/mocks-and-spies.test.ts

@@ -0,0 +1,29 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {expectType} from 'tsd-lite';
+import {jest} from '@jest/globals';
+import type {Mock} from 'jest-mock';
+
+// Mock
+
+const mock1: Mock<number> = jest.fn();
+
+expectType<Mock<number>>(mock1);
+
+// MockedFunction
+
+function testFunction(num: number, str: string): boolean {
+  return true;
+}
+
+const mockedTestFunction = testFunction as jest.MockedFunction<
+  typeof testFunction
+>;
+
+expectType<number>(mockedTestFunction.mock.calls[0][0]);
+expectType<string>(mockedTestFunction.mock.calls[0][1]);

scripts/buildUtils.js

@@ -74,12 +74,12 @@ module.exports.getPackages = function getPackages() {
     if (pkg.types) {
       assert.strictEqual(
         pkg.main,
-        './build/index.js',
+        pkg.name === '@jest/globals' ? './index.js' : './build/index.js',
         `Package "${pkg.name}" should have "./build/index.js" as main`,
       );
       assert.strictEqual(
         pkg.types,
-        './build/index.d.ts',
+        pkg.name === '@jest/globals' ? './index.d.ts' : './build/index.d.ts',
         `Package "${pkg.name}" should have "./build/index.d.ts" as types`,
       );
     } else {

yarn.lock

@@ -2621,6 +2621,7 @@ __metadata:
     "@jest/environment": ^28.0.0-alpha.3
     "@jest/expect": ^28.0.0-alpha.3
     "@jest/types": ^28.0.0-alpha.3
+    jest-mock: ^28.0.0-alpha.3
   languageName: unknown
   linkType: soft