runtime_create_mock_from_module.test.js

/**
 * 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.
 *
 */

'use strict';

let createRuntime;

const moduleNameMapper = {
  'module/name/(.*)': '<rootDir>/mapped_module_$1.js',
};

describe('Runtime', () => {
  beforeEach(() => {
    createRuntime = require('createRuntime');
  });

  describe('createMockFromModule', () => {
    it('does not cause side effects in the rest of the module system when generating a mock', () =>
      createRuntime(__filename).then(runtime => {
        const testRequire = runtime.requireModule.bind(
          runtime,
          runtime.__mockRootPath,
        );

        const module = testRequire('RegularModule');
        const origModuleStateValue = module.getModuleStateValue();

        expect(origModuleStateValue).toBe('default');

        // Generate a mock for a module with side effects
        const mock = module.jest.createMockFromModule('ModuleWithSideEffects');

        // Make sure we get a mock.
        expect(mock.fn()).toBe(undefined);
        expect(module.getModuleStateValue()).toBe(origModuleStateValue);
      }));

    it('resolves mapped modules correctly', () =>
      createRuntime(__filename, {moduleNameMapper}).then(runtime => {
        const root = runtime.requireModule(runtime.__mockRootPath);
        const mockModule = root.jest.createMockFromModule(
          'module/name/createMockFromModule',
        );

        expect(mockModule.test.mock).toBeTruthy();
      }));
  });

  it('creates mock objects in the right environment', () =>
    createRuntime(__filename).then(runtime => {
      const testRequire = runtime.requireModule.bind(
        runtime,
        runtime.__mockRootPath,
      );

      const module = testRequire('RegularModule');
      const mockModule = module.jest.createMockFromModule('RegularModule');
      const testObjectPrototype = Object.getPrototypeOf(module.object);
      const mockObjectPrototype = Object.getPrototypeOf(mockModule.object);
      expect(mockObjectPrototype).toBe(testObjectPrototype);
    }));
});