feat(runtime): add jest.mockModule

Author: SimenB

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

@@ -41,7 +41,7 @@ FAIL __tests__/index.js
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:558:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:557:17)
       at Object.require (index.js:10:1)
 `;
 
@@ -70,6 +70,6 @@ FAIL __tests__/index.js
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:558:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:557:17)
       at Object.require (index.js:10:1)
 `;

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

@@ -10,7 +10,7 @@ Ran all test suites matching /native-esm.tla.test.js/i.
 
 exports[`on node ^12.16.0 || >=13.7.0 runs test with native ESM 1`] = `
 Test Suites: 1 passed, 1 total
-Tests:       18 passed, 18 total
+Tests:       19 passed, 19 total
 Snapshots:   0 total
 Time:        <<REPLACED>>
 Ran all test suites matching /native-esm.test.js/i.

e2e/native-esm/__tests__/native-esm.test.js

@@ -166,3 +166,14 @@ test('handle circular dependency', async () => {
   expect(moduleA.moduleB.id).toBe('circularDependentB');
   expect(moduleA.moduleB.moduleA).toBe(moduleA);
 });
+
+test('can mock module', async () => {
+  jestObject.mockModule('../mockedModule.mjs', () => ({foo: 'bar'}), {
+    virtual: true,
+  });
+
+  const importedMock = await import('../mockedModule.mjs');
+
+  expect(Object.keys(importedMock)).toEqual(['foo']);
+  expect(importedMock.foo).toEqual('bar');
+});

packages/jest-environment/src/index.ts

@@ -137,6 +137,14 @@ export interface Jest {
     moduleFactory?: () => unknown,
     options?: {virtual?: boolean},
   ): Jest;
+  /**
+   * Mocks a module with an auto-mocked version when it is being required.
+   */
+  mockModule(
+    moduleName: string,
+    moduleFactory?: () => Promise<unknown> | unknown,
+    options?: {virtual?: boolean},
+  ): Jest;
   /**
    * Returns the actual module instead of a mock, bypassing all checks on
    * whether the module should receive a mock implementation or not.

packages/jest-resolve/src/index.ts

@@ -313,10 +313,8 @@ export default class Resolver {
   getModuleID(
     virtualMocks: Map<string, boolean>,
     from: Config.Path,
-    _moduleName?: string,
+    moduleName = '',
   ): string {
-    const moduleName = _moduleName || '';
-
     const key = from + path.delimiter + moduleName;
     const cachedModuleID = this._moduleIDCache.get(key);
     if (cachedModuleID) {