index.js

/**
 * 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.mock.calls.length).toBe(1);
  });

  test('second test', () => {
    expect(localClass.test()).toEqual('ABCD');
    expect(localClass.test.mock.calls.length).toBe(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.mock.calls.length).toBe(1);
  });

  test('second test', () => {
    expect(localClass.test()).toEqual('12345');
    expect(localClass.test.mock).toBe(undefined);
  });
});