Add restoreMocks config to fix #3580 (#5327)

* Added restoreMocks config option

* Changed tests to use jest.spyOn, since that's what restore impacts

* Changed tests to use correct toHaveBeenCalled() syntax

* Added changelog entry

Author: gricard

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 * `[jest-cli]` Fix `EISDIR` when a directory is passed as an argument to `jest`.
   ([#5317](https://github.com/facebook/jest/pull/5317))
+* `[jest-config]` Added restoreMocks config option.
+  ([#5327](https://github.com/facebook/jest/pull/5327))
 
 ## jest 22.1.0
 

docs/Configuration.md

@@ -605,6 +605,15 @@ argument:
 The function should either return a path to the module that should be resolved
 or throw an error if the module can't be found.
 
+### `restoreMocks` [boolean]
+
+Default: `false`
+
+Automatically restore mock state between every test. Equivalent to calling
+`jest.restoreAllMocks()` between each test. This will lead to any mocks having
+their fake implementations removed and restores their initial
+implementation.
+
 ### `rootDir` [string]
 
 Default: The root of the directory containing your jest's [config file](#) _or_

docs/MockFunctionAPI.md

@@ -96,6 +96,9 @@ Beware that `mockFn.mockRestore` only works when mock was created with
 `jest.spyOn`. Thus you have to take care of restoration yourself when manually
 assigning `jest.fn()`.
 
+The [`restoreMocks`](configuration.html#restoremocks-boolean) configuration
+option is available to restore mocks automatically between tests.
+
 ### `mockFn.mockImplementation(fn)`
 
 Accepts a function that should be used as the implementation of the mock. The

integration-tests/__tests__/__snapshots__/show_config.test.js.snap

@@ -32,6 +32,7 @@ exports[`--showConfig outputs config info and exits 1`] = `
       \\"name\\": \\"[md5 hash]\\",
       \\"resetMocks\\": false,
       \\"resetModules\\": false,
+      \\"restoreMocks\\": false,
       \\"rootDir\\": \\"<<REPLACED_ROOT_DIR>>\\",
       \\"roots\\": [
         \\"<<REPLACED_ROOT_DIR>>\\"

integration-tests/__tests__/auto_restore_mocks.test.js

@@ -0,0 +1,21 @@
+/**
+ * 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('suite with auto-restore', () => {
+  const result = runJest('auto-restore-mocks/with-auto-restore');
+  expect(result.status).toBe(0);
+});
+
+test('suite without auto-restore', () => {
+  const result = runJest('auto-restore-mocks/without-auto-restore');
+  expect(result.status).toBe(0);
+});

integration-tests/auto-restore-mocks/with-auto-restore/__tests__/index.js

@@ -0,0 +1,22 @@
+/**
+ * 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.
+ */
+
+'use strict';
+
+const TestClass = require('../');
+const localClass = new TestClass();
+
+test('first test', () => {
+  jest.spyOn(localClass, 'test').mockImplementation(() => 'ABCD');
+  expect(localClass.test()).toEqual('ABCD');
+  expect(localClass.test).toHaveBeenCalledTimes(1);
+});
+
+test('second test', () => {
+  expect(localClass.test()).toEqual('12345');
+  expect(localClass.test.mock).toBe(undefined);
+});

integration-tests/auto-restore-mocks/with-auto-restore/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.
+ */
+
+module.exports = class Test {
+  test() {
+    return '12345';
+  }
+};

integration-tests/auto-restore-mocks/with-auto-restore/package.json

@@ -0,0 +1,6 @@
+{
+  "jest": {
+    "testEnvironment": "node",
+    "restoreMocks": true
+  }
+}

integration-tests/auto-restore-mocks/without-auto-restore/__tests__/index.js

@@ -0,0 +1,42 @@
+/**
+ * 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.
+ */
+
+'use strict';
+
+const TestClass = require('../');
+const localClass = new TestClass();
+
+describe('without an explicit restore', () => {
+  jest.spyOn(localClass, 'test').mockImplementation(() => 'ABCD');
+
+  test('first test', () => {
+    expect(localClass.test()).toEqual('ABCD');
+    expect(localClass.test).toHaveBeenCalledTimes(1);
+  });
+
+  test('second test', () => {
+    expect(localClass.test()).toEqual('ABCD');
+    expect(localClass.test).toHaveBeenCalledTimes(2);
+  });
+});
+
+describe('with an explicit restore', () => {
+  beforeEach(() => {
+    jest.restoreAllMocks();
+  });
+
+  test('first test', () => {
+    jest.spyOn(localClass, 'test').mockImplementation(() => 'ABCD');
+    expect(localClass.test()).toEqual('ABCD');
+    expect(localClass.test).toHaveBeenCalledTimes(1);
+  });
+
+  test('second test', () => {
+    expect(localClass.test()).toEqual('12345');
+    expect(localClass.test.mock).toBe(undefined);
+  });
+});

integration-tests/auto-restore-mocks/without-auto-restore/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.
+ */
+
+module.exports = class Test {
+  test() {
+    return '12345';
+  }
+};