unit-testing - 单元测试 redux-saga 任务取消

Question

我想知道是否有人对如何对以下 redux-saga 登录/注销流程进行单元测试有任何提示:

let pollingTask = null

function * handleLogin () {
  try {
    const token = yield call(loginHandler)
    pollingTask = yield fork(handlePolls, token)
    yield put('LOGIN_SUCCSES')
  } catch (e) {
    yield put('LOGIN_FAILURE')
  }
}

function * handlePolls (token) {
  while (true) {
    try {
      yield call(pollHandler, token)
      yield put('POLL_SUCCESS')
    } catch (e) {
      yield put('POLL_FAILURE')
    } finally {
      if (yield cancelled()) {
        yield call(pollCancelled)
      }
    }
  }
}

function * handleLogout () {
  try {
    yield call(logoutHandler)
    yield cancel(pollingTask) 
    yield put('LOGOUT_SUCCESS')
  } catch (e) {
    yield put('LOGOUT_FAILURE')
  }
}

由于我需要取消 pollingTask注销时，我尝试使用 createMockTask()在我的测试中，但我总是得到它的值 undefined当我调用 handleLogout()传奇，虽然我知道我的 handleLogin()将始终首先启动并初始化 pollingTask .

任何帮助将非常感激!

Answer 1

为了让函数去 yield cancelled() 你在迭代器上调用 .return() 。

一个例子 -

//assuming this saga 
function* saga() {
  try {
    const resp = yield call(someApi)
    yield put(action(resp))
  } finally {
    if(yield cancelled()) {
       // handle logic specific to cancellation. For example
       yield <some effect>
    }
  }
}

// test
const gen = saga()
expect(gen.next().value).toEqual(call(someApi))
// simulates cancellation
// gen asking for cancel status
expect(gen.return().value).toEqual( cancelled() ) 
// answer yes, we've been cancelled
expect(gen.next(true).value).toEqual(<some effect>)

示例取自 https://github.com/redux-saga/redux-saga/issues/266#issuecomment-216087030