javascript - ES6 [Symbol.iterator] 不是带数组的函数

Question

我正在尝试测试这个按预期执行的 redux saga 生成器:

export function* mygen(id) {
  let selectedItems = yield select(myselector) //return an array of integer
  for(let item of selectedItems) {
    const {response, error} = yield call(asynFunc, id, item)
    if (response) {
      yield put({type: ACTION_SUCCESS, data: response.data})
    }
    else {
      yield put({type: ACTION_FAILURE, error: error.response.data.error})
    }
  }
}

这是我的测试:

it("myTest", () => {
    const gen = mygen()
    expect(gen.next().value).to.deep.equal(select(myselector))

    expect(gen.next({selectedItems: [1], item:1, id:1})).to.deep.equal(call(asynFunc, 1, 1))

})

我遇到了这个错误:

 TypeError: selectedItems[Symbol.iterator] is not a function

这很奇怪，因为 selectedItems 是一个数组

你知道如何测试它吗？
提前致谢

Answer 1

稍作调整即可通过测试:

import Promise from 'bluebird';
import { delay } from 'redux-saga';
import { call, select } from 'redux-saga/effects';

import { logger } from '../utils';

const name = '21/Test async function';
const log = logger(name);

const delayTime = 10;

const reducer = () => ({ selectedItems: [ 1 ], item: 1, id: 1 });

const myselector = item => item.selectedItems;

const asynFunc = (id, item) => delay(delayTime,  {response: { selectedItems: [ 1 ], item: item, id: id }});

export function* mygen(id) {
  let selectedItems = yield select(myselector); //return an array of integer
  // log('selectedItems', selectedItems);
  for(let item of selectedItems) {
    // log('item', item);
    const {response, } = yield call(asynFunc, id, item);
    // log('response', response);
  }
}


export default  {
  name,
  saga: () => mygen(1),
  reducer: reducer,
  useThunk: !true,
  execute(store) {
    const gen = mygen();

    const value = gen.next().value;
    log('gen.next().value', value);
    log('select(myselector)', select(myselector));
    log('gen.next().value === select(myselector)', JSON.stringify(value) === JSON.stringify(select(myselector)));

    const selectedItems = [1];
    const response = gen.next(selectedItems).value;
    const asyncCallResult = call(asynFunc, 1, 1);
    log(`gen.next([1]).value`, response);
    log(`call(asynFunc, 1, 1)`, asyncCallResult);
    log(`gen.next([1]).value === call(asynFunc, 1, 1)`, JSON.stringify(asyncCallResult) === JSON.stringify(asyncCallResult));

    return delay(2 * delayTime, this);
  }
};

日志看起来像:

   00000000: [Runner] ---------- running example 21/Test async function
   00000003: [Runner] store initial state Object {selectedItems: Array[1], item: 1, id: 1}
   00000010: [21/Test async function] gen.next().value Object {@@redux-saga/IO: true, SELECT: Object}
   00000011: [21/Test async function] select(myselector) Object {@@redux-saga/IO: true, SELECT: Object}
   00000011: [21/Test async function] gen.next().value === select(myselector) true
   00000012: [21/Test async function] gen.next([1]).value Object {@@redux-saga/IO: true, CALL: Object}
   00000012: [21/Test async function] call(asynFunc, 1, 1) Object {@@redux-saga/IO: true, CALL: Object}
   00000013: [21/Test async function] gen.next([1]).value === call(asynFunc, 1, 1) true
 * 00000088: [Runner] store final state Object {selectedItems: Array[1], item: 1, id: 1}
   00000089: [Runner] ---------- example 21/Test async function is done

对于选择器myselector = item => item，selected items 是一个对象并且TypeError: selectedItems[Symbol.iterator] is not a function被抛出:

case 2:
  selectedItems = _context.sent;
  //return an array of integer
  // log('selectedItems', selectedItems);
  _iteratorNormalCompletion = true;
  _didIteratorError = false;
  _iteratorError = undefined;
  _context.prev = 6;
  _iterator = selectedItems[Symbol.iterator](); // selectedItems is not an array