Jest：如何使用 jest.genMockFromModule 的结果

Question

我正在尝试模拟 firebase 模块

在我的__mocks__/firebase.js文件中我只是简单地输入

const mockFirebase = jest.genMockFromModule('firebase');
export default mockFirebase;

在我的代码中如果我这样做

import * as firebase from 'firebase';
console.log(firebase);

我明白了

{ default:
  {
    __esModule: true,
    initializeApp:
    { [Function: initializeApp]
      _isMockFunction: true,
      getMockImplementation: [Function],
      mock: [Getter/Setter],
      mockClear: [Function],
      mockReset: [Function],
      mockReturnValueOnce: [Function],
      mockReturnValue: [Function],
      mockImplementationOnce: [Function],
      mockImplementation: [Function],
      mockReturnThis: [Function],
      mockRestore: [Function] },
    app:
    { [Function: app]
      _isMockFunction: true,
      getMockImplementation: [Function],
      mock: [Getter/Setter],
      mockClear: [Function],
      mockReset: [Function],
      mockReturnValueOnce: [Function],
      mockReturnValue: [Function],
      mockImplementationOnce: [Function],
      mockImplementation: [Function],
      mockReturnThis: [Function],
      mockRestore: [Function],
      App: [Object] },
    apps: [],
    Promise:
    { [Function: Promise]
      _isMockFunction: true,
      getMockImplementation: [Function],
      mock: [Getter/Setter],
      mockClear: [Function],
      mockReset: [Function],
      mockReturnValueOnce: [Function],
      mockReturnValue: [Function],
      mockImplementationOnce: [Function],
      mockImplementation: [Function],
      mockReturnThis: [Function],
      mockRestore: [Function],
      _37: null,
      _87: null,
      _61: [Object],
      resolve: [Object],
      all: [Object],
      reject: [Object],
      race: [Object],
      denodeify: [Object],
      nodeify: [Object],
      enableSynchronous: [Object],
      disableSynchronous: [Object] },
    SDK_VERSION: '4.2.0',
    INTERNAL:
    { registerService: [Object],
      createFirebaseNamespace: [Object],
      extendNamespace: [Object],
      createSubscribe: [Object],
      ErrorFactory: [Object],
      removeApp: [Object],
      factories: [Object],
      useAsService: [Object],
      deepExtend: [Object],
      node: [Object],
      Promise: [Object] },
    auth:
    { [Function: serviceNamespace]
      _isMockFunction: true,
      getMockImplementation: [Function],
      mock: [Getter/Setter],
      mockClear: [Function],
      mockReset: [Function],
      mockReturnValueOnce: [Function],
      mockReturnValue: [Function],
      mockImplementationOnce: [Function],
      mockImplementation: [Function],
      mockReturnThis: [Function],
      mockRestore: [Function],
      Auth: [Object],
      Error: [Object],
      EmailAuthProvider: [Object],
      FacebookAuthProvider: [Object],
      GithubAuthProvider: [Object],
      GoogleAuthProvider: [Object],
      TwitterAuthProvider: [Object],
      OAuthProvider: [Object],
      PhoneAuthProvider: [Object],
      RecaptchaVerifier: [Object] },
    User:
    { [Function: S]
      _isMockFunction: true,
      getMockImplementation: [Function],
      mock: [Getter/Setter],
      mockClear: [Function],
      mockReset: [Function],
      mockReturnValueOnce: [Function],
      mockReturnValue: [Function],
      mockImplementationOnce: [Function],
      mockImplementation: [Function],
      mockReturnThis: [Function],
      mockRestore: [Function],
      Cg: [Object],
      Sc: [Object] },
    database:
    { [Function: serviceNamespace]
      _isMockFunction: true,
      getMockImplementation: [Function],
      mock: [Getter/Setter],
      mockClear: [Function],
      mockReset: [Function],
      mockReturnValueOnce: [Function],
      mockReturnValue: [Function],
      mockImplementationOnce: [Function],
      mockImplementation: [Function],
      mockReturnThis: [Function],
      mockRestore: [Function],
      Reference: [Object],
      Query: [Object],
      Database: [Object],
      enableLogging: [Object],
      INTERNAL: [Object],
      ServerValue: [Object],
      TEST_ACCESS: [Object] },
    default: [Circular]
  } 
}

由此我了解到我正在按预期嘲笑该模块。

我有类似的代码
contactKey = firebase.database().ref().child(path).push().key;

我的测试失败并出现以下错误：

TypeError: firebase.database is not a function

如果我这样做console.log(firebase.default.database)我得到

function serviceNamespace() {return mockConstructor.apply(this,arguments);}

如果我这样做console.log(firebase.default.database())我得到

undefined

我应该如何消费这个模拟？console.log 的输出使得生成的模拟看起来像是我所期望的（或多或少），但没有任何东西是可调用的。

Answer 1

mock在你的-中尝试这样的事情

const push = jest.fn(() => ({ key: 'mockContactKey' }));

const child = jest.fn(() => ({ push }));

const ref = jest.fn(() => ({ child }));

mockFirebase.database = jest.fn(() => ({ ref }));

这就是你所需要contactKey的mockContactKey