测试耗时且来自运算符的史诗

Question

我有这个史诗，需要测试的帮助，对异步方法的史诗调用（来自运算符），它使用了延迟运算符

export const getAll$ = (
  action$: any,
  state: { value: TStore },
  { stock, Error }: TDependencies
) => {
  return action$.pipe(
    ofType(getAll.toString()),
    map(({ meta: { failures} }) => ({
      failures,
    })),
    switchMap(({ failures }) => {
      return merge(
        of(getAllStart()),
        // call api service stock.getAll, this is async
        from(stock.getAll()).pipe(
          // wait a 1 second, not matter if stock.getAll finish early
          delay(OPERATION_DELAY),
          switchMap((response: TGetAllResponse) => {
            if(response instanceof Error) {
              return throwError(response);
            }
            return of(
              getAllSuccess()
            );
          }),
          catchError((error) => {
            return failures === 0 ?
              of(getAllFailure({ error }))
              :
              of(getAll({
                failures: failures + 1,
              })).pipe(
                delay(FAILURE_RETRY_TIME),
              );
          }),
          // "cancel" this epic if getAllAbort action is emitted
          takeUntil(
            action$.ofType(
              getAllAbort.toString()
            )
          )
        )
      )
    })
  )
};

这是我的考试

import { ActionsObservable } from 'redux-observable';

// some mocking

const state = { value: {} };

const dependencies = {
  api: {},
  stock: {
    getAll() {
      return [];
    }
  },
  Error: class Error {},
};

describe('stock epic', () => {
  it('should return all products', (done) => {
    // start epic getAll$
    getAll$(ActionsObservable.of(getAll()), state, dependencies).subscribe((action) => {
      console.log(action); //  { type: 'STOCK/GET_ALL_START' }
      done();
    });
  });
});

如果看到console.log(action);仅返回{ type: 'STOCK/GET_ALL_START' }如果我使用.toArray()，则测试永无止境

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Answer 1

[几个小时后，我找到了解决方案，如果您的史诗使用from运算符，则无法对其进行测试，则需要模拟该运算符，就我而言，我只是将此运算符映射为of运算符很容易，在您的根项目文件夹中创建一个名为__mocks__的文件夹，并在其中创建一个名为rxjs.js的js文件，然后将此代码放入其中]

const rxjs = jest.requireActual('rxjs');
rxjs.from = rxjs.of;
module.exports = rxjs;
然后用于测试您是否需要使用类TestScheduler，它在rxjs/testing中可以作为导出常量使用

代码会这样

import { ActionsObservable } from 'redux-observable';
import { TestScheduler } from 'rxjs/testing';

// your epics to be tested
import epics from './stock';

// actions that you epic will emit
import {
  getAll,
  getAllStart,
  getAllSuccess,
} from '../actions/stock';

// mock the state param (if your epic use it)
import { initialState } from '../reducers/stock';

const state = {
  value: {
    stock: initialState,
  },
};

// mock your dependencies param
const dependencies = {
  api: {},
  stock: {
    getAll() { // in my real code, this is a promise, here is just a normal function, perfect to be use with the of operator
      return [];
    },
  },
  Error: class Error {},
};

describe('stock epic', () => {

  it('should return all products', (done) => {

    // this is just copy-paste
    const testScheduler = new TestScheduler((actual, expected) => {
      expect(actual).toStrictEqual(expected);
    });

    testScheduler.run(({ cold, hot, expectObservable, expectSubscriptions, flush }) => {
      expectObservable(
        epics.getAll$(
          ActionsObservable.of(getAll()), // transform action to action$
          state, // pass mocked state
          dependencies // pass mocked dependencies
        )
      ).toBe(
        // my epic has a delay(1000) call
        'a 999ms (b|)', {
          a: getAllStart(),
          b: getAllSuccess()
        }
      );
      done();
    });
  });

});