如何测试redux-saga延迟

Question

问题

在redux-saga,我正在使用yield delay(1000);.在我的单元测试中,我做到了expect(generator.next().value).toEqual(delay(1000));.

我希望测试通过.

这是我的sagas.js:

import { delay } from 'redux-saga';

export function* incrementAsync() {
  yield delay(1000);
}

这是我的 sagas.test.js

import { delay } from 'redux-saga';
import { incrementAsync } from '../sagas';

describe('incrementAsync Saga test', () => {
  it('should incrementAsync', () => {
    const generator = incrementAsync();
    expect(generator.next().value).toEqual(delay(1000));
  });
});

●incrementAsync Saga test>应该incrementAsync

expect(received).toEqual(expected)

Expected value to equal:
  {"@@redux-saga/CANCEL_PROMISE": [Function anonymous]}
Received:
  {"@@redux-saga/CANCEL_PROMISE": [Function anonymous]}

Difference:

Compared values have no visual difference.

题

我怎样才能测试redux-saga 延迟？

Answer 1

如果你检查delaysaga效果代码,你会发现它是一个绑定函数:

export const delay = call.bind(null, delayUtil)

因此,如果您导入delay两个不同的模块,它将是两个不同的功能,没有视觉差异.

您可以在codesandbox示例中查看此内容(请参阅测试选项卡):

const testFunction = () => {};

describe("example bound functions equality test", () => {
  it("Two bound functions are not equal", () => {
    expect(testFunction.bind(this))
      .not.toEqual(testFunction.bind(this));
  });
});

结果是:

要测试你的传奇,你应该模仿你的delay效果(如果你使用的是Jest);

import { delay } from "redux-saga";
import { incrementAsync } from "../sagas";

jest.mock("redux-saga");

describe("incrementAsync Saga test", () => {
  it("should incrementAsync", () => {
    const generator = incrementAsync();
    expect(generator.next().value).toEqual(delay(1000));
  });
});

Answer 2

测试Redux Saga调用的一个好方法是使用call效果.在这种情况下,您可以按如下方式稍微重构您的传奇:

import { delay } from 'redux-saga';
import { call } from 'redux-saga/effects';

export function* incrementAsync() {
  yield call(delay, 1000);
}

然后你会这样测试:

import { delay } from 'redux-saga';
import { call } from 'redux-saga/effects';

describe('incrementAsync', () => {
  it('should incrementAsync()', () => {
    const generator = incrementAsync();

    expect(generator.next().value).toEqual(call(delay, 1000));
  });
});

这是有效的,因为yield to的结果call是一个简单的对象,描述了对delay函数的调用.不需要任何嘲笑:)

当然还有伟大的redux-saga-test-plan帮助库.使用它,您的测试将变为以下:

import { testSaga } from 'redux-saga-test-plan';
import { delay } from 'redux-saga';
import { call } from 'redux-saga/effects';

describe('incrementAsync', () => {
  it('should incrementAsync()', () => {
    testSaga(incrementAsync)
      .next()
      .call(delay, 1000)
      .next()
      .isDone();
  });
});