Add auto-mock support for generators (#5983)

Author: steven10172

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Features
 
+* `[jest-mock]` Add support for auto-mocking generator functions
+  ([#5983](https://github.com/facebook/jest/pull/5983))
 * `[expect]` Add support for async matchers
   ([#5836](https://github.com/facebook/jest/pull/5919))
 * `[expect]` Suggest toContainEqual

integration-tests/__tests__/generator_mock.test.js

@@ -0,0 +1,17 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. 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.
+ *
+ * @flow
+ */
+'use strict';
+
+const runJest = require('../runJest');
+
+test('mock works with generator', () => {
+  const {status} = runJest('generator-mock');
+
+  expect(status).toBe(0);
+});

integration-tests/generator-mock/__tests__/generator_mock.test.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. 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.
+ */
+
+jest.mock('../index');
+
+const methods = require('../index');
+
+test('mock works with generator', () => {
+  expect(methods.generatorMethod).toBeDefined();
+});

integration-tests/generator-mock/index.js

@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. 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.
+ */
+
+function* generatorMethod() {
+  yield 42;
+}
+
+module.exports.generatorMethod = generatorMethod;

integration-tests/generator-mock/package.json

@@ -0,0 +1,5 @@
+{
+  "jest": {
+    "testEnvironment": "node"
+  }
+}

packages/jest-mock/src/index.js

@@ -161,7 +161,11 @@ function isA(typeName: string, value: any): boolean {
 }
 
 function getType(ref?: any): string | null {
-  if (isA('Function', ref) || isA('AsyncFunction', ref)) {
+  if (
+    isA('Function', ref) ||
+    isA('AsyncFunction', ref) ||
+    isA('GeneratorFunction', ref)
+  ) {
     return 'function';
   } else if (Array.isArray(ref)) {
     return 'array';
@@ -194,7 +198,9 @@ function isReadonlyProp(object: any, prop: string): boolean {
       prop === 'callee' ||
       prop === 'name' ||
       prop === 'length') &&
-      (isA('Function', object) || isA('AsyncFunction', object))) ||
+      (isA('Function', object) ||
+        isA('AsyncFunction', object) ||
+        isA('GeneratorFunction', object))) ||
     ((prop === 'source' ||
       prop === 'global' ||
       prop === 'ignoreCase' ||