fix(jest-resolve-dependencies): resolve mocks as dependencies (#10713)

Co-authored-by: grey275 <pjvanderpol@gmail.com>

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 - `[jest-config]` Fix bug introduced in watch mode by PR[#10678](https://github.com/facebook/jest/pull/10678/files#r511037803) ([#10692](https://github.com/facebook/jest/pull/10692))
 - `[expect]` Stop modifying the sample in `expect.objectContaining()` ([#10711](https://github.com/facebook/jest/pull/10711))
+- `[jest-resolve-dependencies]` Resolve mocks as dependencies ([#10713](https://github.com/facebook/jest/pull/10713))
 
 ### Chore & Maintenance
 

packages/jest-resolve-dependencies/__mocks__/fake-node-module.js

@@ -0,0 +1,9 @@
+/**
+ * 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.
+ *
+ */
+
+module.exports = str => str;

packages/jest-resolve-dependencies/src/__tests__/__fixtures__/hasMocked/__mocks__/file.js

@@ -0,0 +1,9 @@
+/**
+ * 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.
+ *
+ */
+
+module.exports = jest.fn();

packages/jest-resolve-dependencies/src/__tests__/__fixtures__/hasMocked/file.js

@@ -0,0 +1,9 @@
+/**
+ * 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.
+ *
+ */
+
+module.exports = str => str;

packages/jest-resolve-dependencies/src/__tests__/__fixtures__/hasMocked/file.test.js

@@ -0,0 +1,10 @@
+/**
+ * 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.
+ *
+ */
+
+require('./file');
+require('fake-node-module');

packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.ts

@@ -61,6 +61,18 @@ test('resolves dependencies for existing path', () => {
   ]);
 });
 
+test('includes the mocks of dependencies as dependencies', () => {
+  const resolved = dependencyResolver.resolve(
+    path.resolve(__dirname, '__fixtures__/hasMocked/file.test.js'),
+  );
+
+  expect(resolved).toEqual([
+    expect.stringContaining(path.join('hasMocked', 'file.js')),
+    expect.stringContaining(path.join('hasMocked', '__mocks__', 'file.js')),
+    expect.stringContaining(path.join('__mocks__', 'fake-node-module.js')),
+  ]);
+});
+
 test('resolves dependencies for scoped packages', () => {
   const resolved = dependencyResolver.resolve(
     path.resolve(__dirname, '__fixtures__', 'scoped.js'),
@@ -92,6 +104,19 @@ test('resolves inverse dependencies for existing path', () => {
   ]);
 });
 
+test('resolves inverse dependencies of mock', () => {
+  const paths = new Set([
+    path.resolve(__dirname, '__fixtures__/hasMocked/__mocks__/file.js'),
+  ]);
+  const resolved = dependencyResolver.resolveInverse(paths, filter);
+
+  expect(resolved).toEqual([
+    expect.stringContaining(
+      path.join('__tests__/__fixtures__/hasMocked/file.test.js'),
+    ),
+  ]);
+});
+
 test('resolves inverse dependencies from available snapshot', () => {
   const paths = new Set([
     path.resolve(__dirname, '__fixtures__/file.js'),

packages/jest-resolve-dependencies/src/index.ts

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import * as path from 'path';
 import type {Config} from '@jest/types';
 import type {FS as HasteFS} from 'jest-haste-map';
 import type {ResolveModuleConfig, ResolverType} from 'jest-resolve';
@@ -49,7 +50,9 @@ class DependencyResolver {
       if (this._resolver.isCoreModule(dependency)) {
         return acc;
       }
+
       let resolvedDependency;
+      let resolvedMockDependency;
       try {
         resolvedDependency = this._resolver.resolveModule(
           file,
@@ -64,8 +67,31 @@ class DependencyResolver {
         }
       }
 
-      if (resolvedDependency) {
-        acc.push(resolvedDependency);
+      if (!resolvedDependency) {
+        return acc;
+      }
+
+      acc.push(resolvedDependency);
+
+      // If we resolve a dependency, then look for a mock dependency
+      // of the same name in that dependency's directory.
+      resolvedMockDependency = this._resolver.getMockModule(
+        resolvedDependency,
+        path.basename(dependency),
+      );
+
+      if (resolvedMockDependency) {
+        const dependencyMockDir = path.resolve(
+          path.dirname(resolvedDependency),
+          '__mocks__',
+        );
+
+        resolvedMockDependency = path.resolve(resolvedMockDependency);
+
+        // make sure mock is in the correct directory
+        if (dependencyMockDir === path.dirname(resolvedMockDependency)) {
+          acc.push(resolvedMockDependency);
+        }
       }
 
       return acc;