如何在自定义钩子中测试 useEffect？

Question

所以我对使用 react 进行测试还是很陌生。我有一个在组件内部调用的自定义钩子。我正在使用来自react-hook-testing-library 的renderHook 方法。

我需要测试是否调用了自定义钩子内useEffect 内的方法。我似乎无法弄清楚这一点。

在另一种情况下，我需要弄清楚是否没有调用trackPdpGtm。

注意：钩子不返回任何数据。这主要用于发送分析信息。

目前的方法：

使用PdpGtm.js

import { useEffect } from 'react';
import { trackPdpGtm } from 'utils/gtm/pdpGtmUtils';
import _ from 'utils/lodashImports';

export default function useGtmPdp(data = {}) {
  console.log('are you getting called?');
  const { relatedProducts, results, priceInfo, breadcrumbs } = data;
  const relatedProductsLoaded = _.get(relatedProducts, 'relatedProductsLoaded');
  useEffect(() => {
     if (relatedProductsLoaded) {
         trackPdpGtm(data);
     }
  }, [relatedProductsLoaded, results, priceInfo, breadcrumbs]);
}

我需要测试是否调用了trackPdpGtm。还需要检查它是否没有在另一个测试用例中调用。

gtm.test.js

import { renderHook, cleanup, act } from 'react-hooks-testing-library';
import usePdpGtm from 'utils/hooks/gtmHooks/usePdpGtm';
import useListPageGtm from 'utils/hooks/gtmHooks/useListPageGtm';
import { trackPdpGtm } from 'utils/gtm/pdpGtmUtils';
import { trackListPageGtm } from 'utils/gtm/plpGtmUtils';
import { mount, shallow } from 'enzyme';
import { ProductDescriptionComponent } from 'components/business/ProductDescription/ProductDescriptionComponent';

jest.mock('utils/hooks/gtmHooks/usePdpGtm');
jest.mock('utils/hooks/gtmHooks/useListPageGtm');
jest.mock('utils/gtm/pdpGtmUtils');
jest.mock('utils/gtm/plpGtmUtils');

trackPdpGtm.mockImplementation = jest.fn();
// ALSO TRIED trackPdpGtm.mockImplementation(() => jest.fn());
trackListPageGtm.mockImplementation(() => console.log('adadada'));

describe('analytics helper', () => {
  afterEach(cleanup);

  it('should fire usePdpGtm Hook', async (done) => {
    const pdpData = {
      relatedProducts: {
        collectionProducts: [],
        relatedProductsLoaded: true
      },
      productInfo: {
        variants: [{}],
        breadcrumbs: [{}],
        serviceWarrantyDetails: {
          services: [],
          warranties: [{}]
        }
      },
      priceInfo: [{}],
      breadcrumbs: [{}]
    };
    const { result } = renderHook(() => usePdpGtm(pdpData));
    //THIS IS FAILING
    expect(trackPdpGtm).toHaveBeenCalledTimes(1);
    expect(result.current).toBeUndefined();
  });

   it('should fire usePdpGtm Hook without data', () => {
     const { result } = renderHook(() => usePdpGtm(undefined));
    
     // NEED TO TEST IF trackPdpGtm is NOT called. (also failing)

     expect(trackPdpGtm).toNotBeCalled();
     expect(result.current).toBeUndefined();
   });

});

还尝试使用trackGtmPdp.mock.calls.length.toBe(1)。

usePdpGtm 挂钩在 ProductDescriptionComponent 内部调用，并接收一个对象作为其参数。

注意：自定义挂钩在测试期间未运行。我不确定，但在测试运行时不会打印里面的 console.log 语句。

非常感谢任何帮助。

Answer 1

您忘记清除 trackPdpGtm 模拟函数的 mock.calls 和 mock.instances 属性。这就是您的第二个测试用例失败的原因。可以在afterEach钩子中使用jest.clearAllMocks()清除。

例如

usePdpGtm.ts:

// @ts-nocheck
import { useEffect } from 'react';
import { trackPdpGtm } from './pdpGtmUtils';
import _ from 'lodash';

export default function useGtmPdp(data = {}) {
  console.log('are you getting called?');
  const { relatedProducts, results, priceInfo, breadcrumbs } = data;
  const relatedProductsLoaded = _.get(relatedProducts, 'relatedProductsLoaded');
  useEffect(() => {
    if (relatedProductsLoaded) {
      trackPdpGtm(data);
    }
  }, [relatedProductsLoaded, results, priceInfo, breadcrumbs]);
}

pdpGtmUtils.ts:

export function trackPdpGtm(data) {
  console.log('real track pdp gtm implementation');
}

usePdpGtm.test.ts:

import { renderHook, cleanup } from '@testing-library/react-hooks';
import usePdpGtm from './usePdpGtm';
import { trackPdpGtm } from './pdpGtmUtils';

jest.mock('./pdpGtmUtils');

describe('analytics helper', () => {
  afterEach(() => {
    jest.clearAllMocks();
    cleanup();
  });

  it('should fire usePdpGtm Hook', () => {
    const pdpData = {
      relatedProducts: {
        collectionProducts: [],
        relatedProductsLoaded: true,
      },
      productInfo: {
        variants: [{}],
        breadcrumbs: [{}],
        serviceWarrantyDetails: {
          services: [],
          warranties: [{}],
        },
      },
      priceInfo: [{}],
      breadcrumbs: [{}],
    };
    const { result } = renderHook(() => usePdpGtm(pdpData));
    expect(trackPdpGtm).toHaveBeenCalledTimes(1);
    expect(result.current).toBeUndefined();
  });

  it('should fire usePdpGtm Hook without data', () => {
    const { result } = renderHook(() => usePdpGtm(undefined));
    expect(trackPdpGtm).not.toBeCalled();
    expect(result.current).toBeUndefined();
  });
});

单元测试结果：

 PASS  examples/65703648/usePdpGtm.test.ts
  analytics helper
    ✓ should fire usePdpGtm Hook (28 ms)
    ✓ should fire usePdpGtm Hook without data (4 ms)

  console.log
    are you getting called?

      at Object.useGtmPdp [as default] (examples/65703648/usePdpGtm.ts:7:11)

  console.log
    are you getting called?

      at Object.useGtmPdp [as default] (examples/65703648/usePdpGtm.ts:7:11)

----------------|---------|----------|---------|---------|-------------------
File            | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------------|---------|----------|---------|---------|-------------------
All files       |   91.67 |      100 |   66.67 |   91.67 |                   
 pdpGtmUtils.ts |      50 |      100 |       0 |      50 | 2                 
 usePdpGtm.ts   |     100 |      100 |     100 |     100 |                   
----------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        5.167 s