请求取消模块单元测试

请求取消模块是 ts-axios 库核心流程其中一个分支，也是非常重要的模块，我们将从基础库和业务流程模块 2 个方面去编写单元测试。

Cancel 类单元测试

cancel/Cancel.spec.ts：

import Cancel, { isCancel } from '../../src/cancel/Cancel'
describe('cancel:Cancel', () => {
  test('should returns correct result when message is specified', () => {
    const cancel = new Cancel('Operation has been canceled.')
    expect(cancel.message).toBe('Operation has been canceled.')
  })
  test('should returns true if value is a Cancel', () => {
    expect(isCancel(new Cancel())).toBeTruthy()
  })
  test('should returns false if value is not a Cancel', () => {
    expect(isCancel({ foo: 'bar' })).toBeFalsy()
  })
})

CancelToken 类单元测试

cancel/CancelToken.spec.ts：

import CancelToken from '../../src/cancel/CancelToken'
import Cancel from '../../src/cancel/Cancel'
import { Canceler } from '../../src/types'
describe('CancelToken', () => {
  describe('reason', () => {
    test('should returns a Cancel if cancellation has been requested', () => {
      let cancel: Canceler
      let token = new CancelToken(c => {
        cancel = c
      })
      cancel!('Operation has been canceled.')
      expect(token.reason).toEqual(expect.any(Cancel))
      expect(token.reason!.message).toBe('Operation has been canceled.')
    })
    test('should has no side effect if call cancellation for multi times', () => {
      let cancel: Canceler
      let token = new CancelToken(c => {
        cancel = c
      })
      cancel!('Operation has been canceled.')
      cancel!('Operation has been canceled.')
      expect(token.reason).toEqual(expect.any(Cancel))
      expect(token.reason!.message).toBe('Operation has been canceled.')
    })
    test('should returns undefined if cancellation has not been requested', () => {
      const token = new CancelToken(() => {
        // do nothing
      })
      expect(token.reason).toBeUndefined()
    })
  })
  describe('promise', () => {
    test('should returns a Promise that resolves when cancellation is requested', done => {
      let cancel: Canceler
      const token = new CancelToken(c => {
        cancel = c
      })
      token.promise.then(value => {
        expect(value).toEqual(expect.any(Cancel))
        expect(value.message).toBe('Operation has been canceled.')
        done()
      })
      cancel!('Operation has been canceled.')
    })
  })
  describe('throwIfRequested', () => {
    test('should throws if cancellation has been requested', () => {
      let cancel: Canceler
      const token = new CancelToken(c => {
        cancel = c
      })
      cancel!('Operation has been canceled.')
      try {
        token.throwIfRequested()
        fail('Expected throwIfRequested to throw.')
      } catch (thrown) {
        if (!(thrown instanceof Cancel)) {
          fail('Expected throwIfRequested to throw a Cancel, but test threw ' + thrown + '.')
        }
        expect(thrown.message).toBe('Operation has been canceled.')
      }
    })
    test('should does not throw if cancellation has not been requested', () => {
      const token = new CancelToken(() => {
        // do nothing
      })
      token.throwIfRequested()
    })
  })
  describe('source', () => {
    test('should returns an object containing token and cancel function', () => {
      const source = CancelToken.source()
      expect(source.token).toEqual(expect.any(CancelToken))
      expect(source.cancel).toEqual(expect.any(Function))
      expect(source.token.reason).toBeUndefined()
      source.cancel('Operation has been canceled.')
      expect(source.token.reason).toEqual(expect.any(Cancel))
      expect(source.token.reason!.message).toBe('Operation has been canceled.')
    })
  })
})

注意，这里我们使用了 fail 函数表示一个测试的失败，这个并未在 Jest 文档中体现，但它是一个可以用的 API。

Cancel 业务逻辑单元测试

cancel.spec.ts：

import axios from '../src/index'
import { getAjaxRequest } from './helper'
describe('cancel', () => {
  const CancelToken = axios.CancelToken
  const Cancel = axios.Cancel
  beforeEach(() => {
    jasmine.Ajax.install()
  })
  afterEach(() => {
    jasmine.Ajax.uninstall()
  })
  describe('when called before sending request', () => {
    test('should rejects Promise with a Cancel object', () => {
      const source = CancelToken.source()
      source.cancel('Operation has been canceled.')
      return axios
        .get('/foo', {
          cancelToken: source.token
        })
        .catch(reason => {
          expect(reason).toEqual(expect.any(Cancel))
          expect(reason.message).toBe('Operation has been canceled.')
        })
    })
  })
  describe('when called after request has been sent', () => {
    test('should rejects Promise with a Cancel object', done => {
      const source = CancelToken.source()
      axios
        .get('/foo/bar', {
          cancelToken: source.token
        })
        .catch(reason => {
          expect(reason).toEqual(expect.any(Cancel))
          expect(reason.message).toBe('Operation has been canceled.')
          done()
        })
      getAjaxRequest().then(request => {
        source.cancel('Operation has been canceled.')
        setTimeout(() => {
          request.respondWith({
            status: 200,
            responseText: 'OK'
          })
        }, 100)
      })
    })
    test('calls abort on request object', done => {
      const source = CancelToken.source()
      let request: any
      axios
        .get('/foo/bar', {
          cancelToken: source.token
        })
        .catch(() => {
          expect(request.statusText).toBe('abort')
          done()
        })
      getAjaxRequest().then(req => {
        source.cancel()
        request = req
      })
    })
  })
  describe('when called after response has been received', () => {
    test('should not cause unhandled rejection', done => {
      const source = CancelToken.source()
      axios
        .get('/foo', {
          cancelToken: source.token
        })
        .then(() => {
          window.addEventListener('unhandledrejection', () => {
            done.fail('Unhandled rejection.')
          })
          source.cancel()
          setTimeout(done, 100)
        })
      getAjaxRequest().then(request => {
        request.respondWith({
          status: 200,
          responseText: 'OK'
        })
      })
    })
  })
})

注意这里我们使用了 done.fail 表示了一个异常的结束，这个并未在 Jest 文档中体现，但它是一个可以用的 API。
至此，我们完成了取消模块相关业务逻辑的单元测试，我们测试覆盖率达到了阈值，测试已经通过了。但是扔未达到我们的目标，还有很多 feature 是没有覆盖到的。接下来我们就完成剩余 feature 的编写单元测试。