feat(@jest/globals): add jest.Mocked, jest.MockedClass, jest.MockedFunction and jest.MockedObject utility types (#12727)

Author: mrazauskas

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - `[jest-config]` [**BREAKING**] Make `snapshotFormat` default to `escapeString: false` and `printBasicPrototype: false` ([#13036](https://github.com/facebook/jest/pull/13036))
 - `[jest-environment-jsdom]` [**BREAKING**] Upgrade to `jsdom@20` ([#13037](https://github.com/facebook/jest/pull/13037), [#13058](https://github.com/facebook/jest/pull/13058))
+- `[@jest/globals]` Add `jest.Mocked`, `jest.MockedClass`, `jest.MockedFunction` and `jest.MockedObject` utility types ([#12727](https://github.com/facebook/jest/pull/12727))
 - `[jest-mock]` [**BREAKING**] Refactor `Mocked*` utility types. `MaybeMockedDeep` and `MaybeMocked` became `Mocked` and `MockedShallow` respectively; only deep mocked variants of `MockedClass`, `MockedFunction` and `MockedObject` are exported ([#13123](https://github.com/facebook/jest/pull/13123), [#13124](https://github.com/facebook/jest/pull/13124))
 - `[jest-worker]` Adds `workerIdleMemoryLimit` option which is used as a check for worker memory leaks >= Node 16.11.0 and recycles child workers as required. ([#13056](https://github.com/facebook/jest/pull/13056), [#13105](https://github.com/facebook/jest/pull/13105), [#13106](https://github.com/facebook/jest/pull/13106), [#13107](https://github.com/facebook/jest/pull/13107))
 - `[pretty-format]` [**BREAKING**] Remove `ConvertAnsi` plugin in favour of `jest-serializer-ansi-escapes` ([#13040](https://github.com/facebook/jest/pull/13040))

docs/MockFunctionAPI.md

@@ -520,3 +520,28 @@ test('calculate calls add', () => {
   expect(mockAdd).toBeCalledWith(1, 2);
 });
 ```
+
+### `jest.Mocked<Source>`
+
+The `jest.Mocked<Source>` utility type returns the `Source` type wrapped with type definitions of Jest mock function.
+
+```ts
+import fetch from 'node-fetch';
+import {expect, jest, test} from '@jest/globals';
+
+jest.mock('node-fetch');
+
+let mockedFetch: jest.Mocked<typeof fetch>;
+
+test('makes correct call', () => {
+  mockedFetch = getMockedFetch();
+  // ...
+});
+
+test('returns correct data', () => {
+  mockedFetch = getMockedFetch();
+  // ...
+});
+```
+
+Types of classes, functions or objects can be passed as type argument to `jest.Mocked<Source>`. If you prefer to constrain the input type, use: `jest.MockedClass<Source>`, `jest.MockedFunction<Source>` or `jest.MockedObject<Source>`.

packages/jest-globals/package.json

@@ -22,7 +22,8 @@
   "dependencies": {
     "@jest/environment": "workspace:^",
     "@jest/expect": "workspace:^",
-    "@jest/types": "workspace:^"
+    "@jest/types": "workspace:^",
+    "jest-mock": "workspace:^"
   },
   "publishConfig": {
     "access": "public"

packages/jest-globals/src/index.ts

@@ -8,8 +8,14 @@
 import type {Jest} from '@jest/environment';
 import type {JestExpect} from '@jest/expect';
 import type {Global} from '@jest/types';
-
-export declare const jest: Jest;
+import type {
+  ClassLike,
+  FunctionLike,
+  Mocked as JestMocked,
+  MockedClass as JestMockedClass,
+  MockedFunction as JestMockedFunction,
+  MockedObject as JestMockedObject,
+} from 'jest-mock';
 
 export declare const expect: JestExpect;
 
@@ -26,6 +32,30 @@ export declare const beforeEach: Global.GlobalAdditions['beforeEach'];
 export declare const afterEach: Global.GlobalAdditions['afterEach'];
 export declare const afterAll: Global.GlobalAdditions['afterAll'];
 
+declare const jest: Jest;
+
+// eslint-disable-next-line @typescript-eslint/no-namespace
+declare namespace jest {
+  /**
+   * Wraps a class, function or object type with Jest mock type definitions.
+   */
+  export type Mocked<T extends object> = JestMocked<T>;
+  /**
+   * Wraps a class type with Jest mock type definitions.
+   */
+  export type MockedClass<T extends ClassLike> = JestMockedClass<T>;
+  /**
+   * Wraps a function type with Jest mock type definitions.
+   */
+  export type MockedFunction<T extends FunctionLike> = JestMockedFunction<T>;
+  /**
+   * Wraps an object type with Jest mock type definitions.
+   */
+  export type MockedObject<T extends object> = JestMockedObject<T>;
+}
+
+export {jest};
+
 throw new Error(
   'Do not import `@jest/globals` outside of the Jest test environment',
 );

packages/jest-globals/tsconfig.json

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

packages/jest-types/__typetests__/jest.test.ts

@@ -7,7 +7,15 @@
 
 import {expectAssignable, expectError, expectType} from 'tsd-lite';
 import {jest} from '@jest/globals';
-import type {Mock, ModuleMocker, SpyInstance} from 'jest-mock';
+import type {
+  Mock,
+  Mocked,
+  MockedClass,
+  MockedFunction,
+  MockedObject,
+  ModuleMocker,
+  SpyInstance,
+} from 'jest-mock';
 
 expectType<typeof jest>(
   jest
@@ -210,7 +218,7 @@ expectType<ModuleMocker['fn']>(jest.fn);
 
 expectType<ModuleMocker['spyOn']>(jest.spyOn);
 
-// deep mocked()
+// Mocked*<T>
 
 class SomeClass {
   constructor(one: string, two?: boolean) {}
@@ -223,6 +231,10 @@ class SomeClass {
   }
 }
 
+function someFunction(a: string, b?: number): boolean {
+  return true;
+}
+
 const someObject = {
   SomeClass,
 
@@ -248,6 +260,24 @@ const someObject = {
   someClassInstance: new SomeClass('value'),
 };
 
+expectType<Mocked<typeof someObject>>(
+  someObject as jest.Mocked<typeof someObject>,
+);
+
+expectType<MockedClass<typeof SomeClass>>(
+  SomeClass as jest.MockedClass<typeof SomeClass>,
+);
+
+expectType<MockedFunction<typeof someFunction>>(
+  someFunction as jest.MockedFunction<typeof someFunction>,
+);
+
+expectType<MockedObject<typeof someObject>>(
+  someObject as jest.MockedObject<typeof someObject>,
+);
+
+// deep mocked()
+
 const mockObjectA = jest.mocked(someObject, true);
 
 expectError(jest.mocked('abc', true));

yarn.lock

@@ -2717,6 +2717,7 @@ __metadata:
     "@jest/environment": "workspace:^"
     "@jest/expect": "workspace:^"
     "@jest/types": "workspace:^"
+    jest-mock: "workspace:^"
   languageName: unknown
   linkType: soft