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

CHANGELOG.md

@@ -30,6 +30,7 @@
 - `[jest-leak-detector]` [**BREAKING**] Use `weak-napi` instead of `weak` package ([#8686](https://github.com/facebook/jest/pull/8686))
 - `[jest-mock]` Fix for mockReturnValue overriding mockImplementationOnce ([#8398](https://github.com/facebook/jest/pull/8398))
 - `[jest-reporters]` Make node-notifer an optional dependency ([#8918](https://github.com/facebook/jest/pull/8918))
+- `[jest-resolve-dependencies]` Resolve mocks as dependencies ([#8952](https://github.com/facebook/jest/pull/8952))
 - `[jest-snapshot]` Remove only the added newlines in multiline snapshots ([#8859](https://github.com/facebook/jest/pull/8859))
 - `[jest-snapshot]` Distinguish empty string from external snapshot not written ([#8880](https://github.com/facebook/jest/pull/8880))
 - `[jest-snapshot]` [**BREAKING**] Distinguish empty string from internal snapshot not written ([#8898](https://github.com/facebook/jest/pull/8898))

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 +1,9 @@
+/**
+ * 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.
+ *
+ */
+
+require('./file');

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

@@ -58,6 +58,17 @@ 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')),
+  ]);
+});
+
 test('resolves dependencies for scoped packages', () => {
   const resolved = dependencyResolver.resolve(
     path.resolve(__dirname, '__fixtures__', 'scoped.js'),
@@ -89,6 +100,19 @@ 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 {Config} from '@jest/types';
 // eslint-disable-next-line import/no-extraneous-dependencies
 import {FS as HasteFS} from 'jest-haste-map';
@@ -51,19 +52,47 @@ class DependencyResolver {
       if (this._resolver.isCoreModule(dependency)) {
         return acc;
       }
+
       let resolvedDependency;
+      let resolvedMockDependency;
       try {
         resolvedDependency = this._resolver.resolveModule(
           file,
           dependency,
           options,
         );
       } catch (e) {
-        resolvedDependency = this._resolver.getMockModule(file, dependency);
+        // TODO: This snippet might not be necessary, should be investigated later.
+        const mockDependency = this._resolver.getMockModule(file, dependency);
+        mockDependency && acc.push(mockDependency);
+        return acc;
+      }
+
+      if (!resolvedDependency) {
+        return acc;
       }
 
-      if (resolvedDependency) {
-        acc.push(resolvedDependency);
+      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(
+        path.dirname(resolvedDependency),
+        path.basename(dependency),
+      );
+
+      if (resolvedMockDependency) {
+        const dependencyMockDir = path.join(
+          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;
@@ -127,8 +156,9 @@ class DependencyResolver {
     }
     const modules: Array<DependencyResolver.ResolvedModule> = [];
     for (const file of this._hasteFS.getAbsoluteFileIterator()) {
+      const res = this.resolve(file, options);
       modules.push({
-        dependencies: this.resolve(file, options),
+        dependencies: res,
         file,
       });
     }