javascript - 在 if 语句中测试 redux-saga 并使用真实值

Question

如何在 if 语句或 try/catch 中测试函数？例如，

export function* onFetchMessages(channel) {
    yield put(requestMessages())
    const channel_name = channel.payload
    try {
        const response = yield call(fetch,'/api/messages/'+channel_name)

        if(response.ok){
            const res = yield response.json();

            const date = moment().format('lll');
            yield put(receiveMessages(res,channel.payload,date))
        }


    } catch (error){
        yield put(rejectMessages(error))
    }
}

我需要输入数据库中实际存在的真实 channel 名称，以便它为后续执行的 yield 返回有效响应，否则会抛出错误。另外，我会收到一条错误消息，无法读取未定义的属性json，因此由于此错误消息，之后的yield无法达到。 所以我的第一个问题是“if(response.ok)”，但即使我删除它，yield response.json()也会返回错误，此外之后的yield也不会被执行。 如果有人能告诉我如何测试这些，我将不胜感激。

Answer 1

将响应对象传递给先前的执行并测试条件，我会这样做，希望这有帮助:

 export function* onFetchMessages(channel) {
try {
    yield put(requestMessages())
    const channel_name = channel.payload
    const response = yield call(fetch,'/api/messages/'+channel_name)

    if(response.ok){
        const res = yield response.json();

        const date = moment().format('lll');
        yield put(receiveMessages(res,channel.payload,date))
    }

   } catch (error){
      yield put(rejectMessages(error))
  }
}

describe('onFetchMessages Saga', () => {
 let output = null;
 const saga = onFetchMessages(channel); //mock channel somewhere...

 it('should put request messages', () => {
  output = saga.next().value;
  let expected = put(requestMessages()); //make sure you import this dependency
  expect(output).toEqual(expected);
 });

 it('should call fetch...blabla', ()=> {
  output = saga.next(channel_name).value; //include channel_name so it is avaiable on the next iteration
  let expected = call(fetch,'/api/messages/'+channel_name); //do all the mock you ned for this
  expect(output).toEqual(expected);
 });

 /*here comes you answer*/
 it('should take response.ok into the if statemenet', ()=> {
  //your json yield is out the redux-saga context so I dont assert it
   saga.next(response).value; //same as before, mock it with a ok property, so it is available
   output = saga.next(res).value; //assert the put effect
   let expected = put(receiveMessages(res,channel.payload,date)); //channel should be mock from previous test
   expect(output).toEqual(expected);
 });

});

请注意，您的代码可能做了更多我不知道的事情，但这至少应该让您在某些行中解决您的问题。