Ensure mocks get resolved too (#7687)

CHANGELOG.md

@@ -124,6 +124,7 @@
 - `[babel-plugin-jest-hoist]` Ignore TS type annotations when looking for out-of-scope references ([#7641](https://github.com/facebook/jest/pull/7641))
 - `[jest-config]` Add name to project if one does not exist to pick correct resolver ([#5862](https://github.com/facebook/jest/pull/5862))
 - `[jest-runtime]` Pass `watchPathIgnorePatterns` to Haste instance ([#7585](https://github.com/facebook/jest/pull/7585))
+- `[jest-runtime]` Resolve mock files via Haste when using `require.resolve` ([#7687](https://github.com/facebook/jest/pull/7585))
 
 ### Chore & Maintenance
 

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

@@ -30,6 +30,6 @@ FAIL __tests__/index.js
       12 | module.exports = () => 'test';
       13 | 
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:433:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/index.js:435:17)
       at Object.require (index.js:10:1)
 `;

e2e/__tests__/__snapshots__/resolveNoFileExtensions.test.js.snap

@@ -33,6 +33,6 @@ FAIL __tests__/test.js
         |                  ^
       4 | 
 
-      at Resolver.resolveModule (../../packages/jest-resolve/build/index.js:200:17)
+      at Resolver.resolveModule (../../packages/jest-resolve/build/index.js:202:17)
       at Object.require (index.js:3:18)
 `;

e2e/resolve/Test5.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.
+ *
+ * @providesModule Test5
+ */
+
+module.exports = {key: 'real'};

e2e/resolve/__mocks__/Test5.js

@@ -0,0 +1,8 @@
+/**
+ * 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 = {key: 'mock'};

e2e/resolve/__mocks__/Test6.js

@@ -0,0 +1,8 @@
+/**
+ * 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 = {key: 'mock'};

e2e/resolve/__tests__/resolve.test.js

@@ -67,3 +67,34 @@ test('should preserve identity for symlinks', () => {
     require('jest-resolve')
   );
 });
+
+test('should require resolve haste files correctly', () => {
+  // We unmock Test5 (they should already be, but to be sure).
+  jest.unmock('Test5');
+
+  // Test5 is a standard module, that has a mock (but it is unmocked here).
+  expect(require.resolve('Test5')).toBe(require.resolve('../Test5'));
+
+  expect(require('Test5').key).toBe('real');
+
+  // Test6 only exits as a mock; so even when unmocked, we resolve to the mock.
+  expect(require.resolve('Test6')).toBe(require.resolve('../__mocks__/Test6'));
+
+  expect(require('Test6').key).toBe('mock');
+});
+
+test('should require resolve haste mocks correctly', () => {
+  // Now we mock Test5 and Test6.
+  jest.mock('Test5');
+  jest.mock('Test6');
+
+  // The resolution still points to the real one, but requires the mock.
+  expect(require.resolve('Test5')).toBe(require.resolve('../Test5'));
+
+  expect(require('Test5').key).toBe('mock');
+
+  // And Test6 points to the mock, because Test6 does not exist as a module.
+  expect(require.resolve('Test6')).toBe(require.resolve('../__mocks__/Test6'));
+
+  expect(require('Test6').key).toBe('mock');
+});

e2e/resolve/hasteImpl.js

@@ -0,0 +1,20 @@
+/**
+ * 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.
+ *
+ * @noflow
+ */
+
+const path = require('path');
+
+module.exports = {
+  getHasteName(filePath) {
+    const name = path.parse(filePath).name;
+    const isMock = filePath.indexOf('__mocks__') !== -1;
+
+    // Mocks are automatically parsed by Jest already.
+    return name.startsWith('Test') && !isMock ? name : null;
+  },
+};

e2e/resolve/package.json

@@ -5,7 +5,8 @@
       "platforms": [
         "native"
       ],
-      "defaultPlatform": "android"
+      "defaultPlatform": "android",
+      "hasteImplModulePath": "<rootDir>/hasteImpl.js"
     },
     "testEnvironment": "node",
     "moduleNameMapper": {

packages/jest-resolve/src/index.js

@@ -122,6 +122,8 @@ class Resolver {
     const key = dirname + path.delimiter + moduleName;
     const defaultPlatform = this._options.defaultPlatform;
     const extensions = this._options.extensions.slice();
+    let module;
+
     if (this._supportsNativePlatform) {
       extensions.unshift(
         ...this._options.extensions.map(ext => '.' + NATIVE_PLATFORM + ext),
@@ -133,24 +135,24 @@ class Resolver {
       );
     }
 
-    // 0. If we have already resolved this module for this directory name,
+    // 1. If we have already resolved this module for this directory name,
     // return a value from the cache.
     if (this._moduleNameCache[key]) {
       return this._moduleNameCache[key];
     }
 
-    // 1. Check if the module is a haste module.
+    // 2. Check if the module is a haste module.
-    let module = this.getModule(moduleName);
+    module = this.getModule(moduleName);
     if (module) {
       return (this._moduleNameCache[key] = module);
     }
 
-    // 2. Check if the module is a node module and resolve it based on
+    // 3. Check if the module is a node module and resolve it based on
-    //    the node module resolution algorithm.
+    // the node module resolution algorithm. If skipNodeResolution is given we
-    // If skipNodeResolution is given we ignore all modules that look like
+    // ignore all modules that look like node modules (ie. are not relative
-    // node modules (ie. are not relative requires). This enables us to speed
+    // requires). This enables us to speed up resolution when we build a
-    // up resolution when we build a dependency graph because we don't have
+    // dependency graph because we don't have to look at modules that may not
-    // to look at modules that may not exist and aren't mocked.
+    // exist and aren't mocked.
     const skipResolution =
       options && options.skipNodeResolution && !moduleName.includes(path.sep);
 
@@ -173,7 +175,7 @@ class Resolver {
       }
     }
 
-    // 3. Resolve "haste packages" which are `package.json` files outside of
+    // 4. Resolve "haste packages" which are `package.json` files outside of
     // `node_modules` folders anywhere in the file system.
     const parts = moduleName.split('/');
     const hastePackage = this.getPackage(parts.shift());
@@ -206,9 +208,9 @@ class Resolver {
     );
     if (module) return module;
 
-    // (4.) Throw an error if the module could not be found. `resolve.sync`
+    // 5. Throw an error if the module could not be found. `resolve.sync` only
-    //      only produces an error based on the dirname but we have the actual
+    // produces an error based on the dirname but we have the actual current
-    //      current module name available.
+    // module name available.
     const relativePath = path.relative(dirname, from);
     const err = new Error(
       `Cannot find module '${moduleName}' from '${relativePath || '.'}'`,

packages/jest-runtime/src/index.js

@@ -589,8 +589,17 @@ class Runtime {
         )}'] from ${from}`,
       );
     }
-
+    try {
       return this._resolveModule(from, moduleName);
+    } catch (err) {
+      const module = this._resolver.getMockModule(from, moduleName);
+
+      if (module) {
+        return module;
+      } else {
+        throw err;
+      }
+    }
   }
 
   _requireResolvePaths(from: Path, moduleName?: string) {