差異處
這裏顯示兩個版本的差異處。
web:reactjs:test:teststaticmethod [2019/03/10 17:16] tony |
web:reactjs:test:teststaticmethod [2023/06/25 09:48] |
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- | {{tag>reactjs}} | ||
- | ====== React - How to test component with static method? ====== | ||
- | ===== Problem ===== | ||
- | 在撰寫程式時,我會習慣將同性質的utility method放在同一個class中。以實作Login、Logout的功能來說,我就會建立一個class叫Auth,會包含以下methods: | ||
- | <code javascript> | ||
- | import React, { Component } from 'react'; | ||
- | const session_token_key = 'session_token'; | ||
- | |||
- | export default class Auth extends Component { | ||
- | | ||
- | static signIn(username, password){ | ||
- | // check credential | ||
- | sessionStorage.setItem(session_token_key, 'session_info'); | ||
- | } | ||
- | |||
- | static signOut(){ | ||
- | sessionStorage.clear(); | ||
- | } | ||
- | |||
- | static checkLogin(){ | ||
- | if( !sessionStorage.getItem(session_token_key) ) { | ||
- | throw new Error("no session info"); | ||
- | } | ||
- | } | ||
- | }; | ||
- | </code> | ||
- | 而Logout的元件中,則會透過Auth.signOut去執行登出的動作: | ||
- | <code javascript> | ||
- | import React, { useContext } from 'react'; | ||
- | import Auth from './Auth' | ||
- | import { NavItem, NavLink} from 'reactstrap'; | ||
- | import { AuthContext } from './AuthContext'; | ||
- | |||
- | |||
- | function Logout(){ | ||
- | const [ authState, setAuthState ] = useContext(AuthContext); | ||
- | |||
- | const signOut = ()=>{ | ||
- | Auth.signOut(); | ||
- | setAuthState(false); | ||
- | window.location.href = '/'; | ||
- | }; | ||
- | |||
- | return ( | ||
- | <NavItem aria-label="logout-nav-item" className="d-md-down-none" onClick={signOut}> | ||
- | <NavLink href="#" ><i className="icon-logout"></i></NavLink> | ||
- | </NavItem> | ||
- | ); | ||
- | } | ||
- | |||
- | export default Logout; | ||
- | </code> | ||
- | 在先前針對[[web:reactjs:react_hook:usecontext|useContext]]的使用文章中,參考過別人使用jest mock static的寫法如下: | ||
- | <code javascript> | ||
- | const auth_do_nothing = jest.fn(); | ||
- | auth_do_nothing.mockImplementation(()=>{}); | ||
- | Auth.signOut = auth_do_nothing.bind(Auth); | ||
- | </code> | ||
- | 但這寫法存在會將狀態延續至下一個testcase中(testsuite似乎沒影響);因此本篇文章將分享透過[[https://sinonjs.org/releases/latest/|Sinon]]去mock static method並且清除mock狀態的做法。 | ||
- | ===== How to? ===== | ||
- | 以Logout為例,我想要模擬使用者點擊Logout並透過Auth.signOut執行登出動作,完整的測試程式碼如下: | ||
- | <code javascript> | ||
- | import Logout from '../Logout' | ||
- | import React, { useState, useEffect } from 'react'; | ||
- | import { AuthContext } from '../AuthContext'; | ||
- | import { render, fireEvent } from 'react-testing-library'; | ||
- | import Auth from '../Auth'; | ||
- | import sinon from 'sinon'; | ||
- | |||
- | let authState = true; | ||
- | function LogoutComp(){ | ||
- | const [ state, setState ] = useState(true); | ||
- | useEffect(()=>{ | ||
- | authState = state; | ||
- | }); | ||
- | return <AuthContext.Provider value={[state, setState]}><Logout/></AuthContext.Provider>; | ||
- | } | ||
- | |||
- | describe('<Logout/>',()=>{ | ||
- | let stubSignOut; | ||
- | beforeEach(()=>{ | ||
- | stubSignOut = sinon.stub(Auth, 'signOut'); | ||
- | }); | ||
- | |||
- | afterEach(()=>{ | ||
- | stubSignOut.restore(); | ||
- | }); | ||
- | |||
- | it('Test logout', () => { | ||
- | // given | ||
- | const utils = render(<LogoutComp/>); | ||
- | const logout_nav_item = utils.getByLabelText('logout-nav-item'); | ||
- | |||
- | // when | ||
- | fireEvent.click(logout_nav_item); | ||
- | |||
- | // then | ||
- | expect(authState).toBe(false); | ||
- | expect(stubSignOut.called).toBe(true); | ||
- | }); | ||
- | }); | ||
- | </code> | ||
- | 在test beforeEach中,我透過sinon.stub去模擬Auth.signOut doNothing的動作,即不給予任何的動作;而在afterEach中,我可以透過stub產生的instance去做restore的動作,讓Auth.signOut回復到模擬之前: | ||
- | <code javascript> | ||
- | let stubSignOut; | ||
- | beforeEach(()=>{ | ||
- | stubSignOut = sinon.stub(Auth, 'signOut'); | ||
- | }); | ||
- | |||
- | afterEach(()=>{ | ||
- | stubSignOut.restore(); | ||
- | }); | ||
- | </code> | ||
- | 如果要驗證stub method是否有被呼叫,可以使用下面的做法: | ||
- | <code javascript> | ||
- | expect(stubSignOut.called).toBe(true); | ||
- | </code> | ||
- | 假如我是在Login form中想要模擬登入失敗的情形呢? 假如我一樣用signOut當範例,我可以在stubSignOut instance上指定要拋出怎樣的例外: | ||
- | <code javascript> | ||
- | it('Test stub with throw', ()=> { | ||
- | stubSignOut.throws("name", "message"); | ||
- | try { | ||
- | Auth.signOut(); | ||
- | fail("should be failed"); | ||
- | } catch(e) { | ||
- | expect(e.name).toBe("name"); | ||
- | expect(e.message).toBe("message"); | ||
- | } | ||
- | expect(stubSignOut.called).toBe(true); | ||
- | }); | ||
- | </code> | ||
- | 假如我要模擬的是回傳值,可以透過以下方式: | ||
- | <code javascript> | ||
- | it('Test stub with return value', ()=> { | ||
- | stubSignOut.returns(true); | ||
- | expect(Auth.signOut()).toBe(true); | ||
- | expect(stubSignOut.called).toBe(true); | ||
- | }); | ||
- | </code> | ||
- | 假如我要模擬有帶參數的情況呢? 以login失敗為例,可以使用withArgs來達到這個需求: | ||
- | <code javascript> | ||
- | it('Test stub with arguments', ()=> { | ||
- | stubSignIn.withArgs('root', '123456').throws("login failed", "wrong password"); | ||
- | try { | ||
- | Auth.signIn('root', '123456'); | ||
- | fail("should be failed"); | ||
- | } catch(e) { | ||
- | expect(e.name).toBe("login failed"); | ||
- | expect(e.message).toBe("wrong password"); | ||
- | } | ||
- | expect(stubSignIn.called).toBe(true); | ||
- | }); | ||
- | </code> | ||
- | 可以看到sinon stub可以滿足我們基本的需求,而且使用也相當容易。我唯一在意的是它stub方式,需要將method name傳遞進去;假如以後有rename的需求,這會不容易馬上察覺。針對這個問題,如果之後有看到其它方法,會再分享給各位。 | ||
- | ===== Reference ===== | ||
- | * [[https://sinonjs.org/releases/v7.2.7/stubs/|Stubs - Sinon.JS]] | ||
- | * [[https://www.robinwieruch.de/react-fetching-data/|How to fetch data in React?]] | ||
- | |||
- | ===== ===== | ||
- | ---- | ||
- | \\ | ||
- | ~~DISQUS~~ |