jest.js — react Source File

Source Code

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * 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';

/* eslint-disable no-unused-vars */

type JestMockFn<TArguments: $ReadOnlyArray<any>, TReturn> = {
  (...args: TArguments): TReturn,
  /**
   * An object for introspecting mock calls
   */
  mock: {
    /**
     * An array that represents all calls that have been made into this mock
     * function. Each call is represented by an array of arguments that were
     * passed during the call.
     */
    calls: Array<TArguments>,
    /**
     * An array that contains all the object instances that have been
     * instantiated from this mock function.
     */
    instances: Array<TReturn>,
    /**
     * An array that contains all the object results that have been
     * returned by this mock function call
     */
    results: Array<{isThrow: boolean, value: TReturn}>,
  },
  /**
   * Resets all information stored in the mockFn.mock.calls and
   * mockFn.mock.instances arrays. Often this is useful when you want to clean
   * up a mock's usage data between two assertions.
   */
  mockClear(): void,
  /**
   * Resets all information stored in the mock. This is useful when you want to
   * completely restore a mock back to its initial state.
   */
  mockReset(): void,
  /**
   * Removes the mock and restores the initial implementation. This is useful
   * when you want to mock functions in certain test cases and restore the
   * original implementation in others. 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().
   */
  mockRestore(): void,
  /**
   * Accepts a function that should be used as the implementation of the mock.
   * The mock itself will still record all calls that go into and instances
   * that come from itself -- the only difference is that the implementation
   * will also be executed when the mock is called.
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