Jest 预期模拟函数已被调用,但未被调用

IT技术 javascript reactjs babeljs jestjs enzyme
2021-04-25 17:29:59

我查看了解决测试类属性但没有成功的各种建议,并想知道是否有人可以更清楚地了解我可能出错的地方,这里是我尝试过的所有测试,错误为 Expected mock函数已被调用,但未调用。

搜索.jsx

import React, { Component } from 'react'
import { func } from 'prop-types'
import Input from './Input'
import Button from './Button'

class SearchForm extends Component {
  static propTypes = {
    toggleAlert: func.isRequired
  }

  constructor() {
    super()

    this.state = {
      searchTerm: ''
    }

    this.handleSubmit = this.handleSubmit.bind(this)
  }

  handleSubmit = () => {
    const { searchTerm } = this.state
    const { toggleAlert } = this.props

    if (searchTerm === 'mocky') {
      toggleAlert({
        alertType: 'success',
        alertMessage: 'Success!!!'
      })

      this.setState({
        searchTerm: ''
      })
    } else {
      toggleAlert({
        alertType: 'error',
        alertMessage: 'Error!!!'
      })
    }
  }

  handleChange = ({ target: { value } }) => {
    this.setState({
      searchTerm: value
    })
  }

  render() {
    const { searchTerm } = this.state
    const btnDisabled = (searchTerm.length === 0) === true

    return (
      <div className="well search-form soft push--bottom">
        <ul className="form-fields list-inline">
          <li className="flush">
            <Input
              id="search"
              name="search"
              type="text"
              placeholder="Enter a search term..."
              className="text-input"
              value={searchTerm}
              onChange={this.handleChange}
            />
            <div className="feedback push-half--right" />
          </li>
          <li className="push-half--left">
            <Button className="btn btn--positive" disabled={btnDisabled} onClick={this.handleSubmit}>
              Search
            </Button>
          </li>
        </ul>
      </div>
    )
  }
}

export default SearchForm

第一个选项:

it('should call handleSubmit function on submit', () => {
    const wrapper = shallow(<Search toggleAlert={jest.fn()} />)
    const spy = jest.spyOn(wrapper.instance(), 'handleSubmit')
    wrapper.instance().forceUpdate()
    wrapper.find('.btn').simulate('click')
    expect(spy).toHaveBeenCalled()
    spy.mockClear()
  })

第二种选择:

it('should call handleSubmit function on submit', () => {
    const wrapper = shallow(<Search toggleAlert={jest.fn()} />)
    wrapper.instance().handleSubmit = jest.fn()
    wrapper.update()
    wrapper.find('.btn').simulate('click')
    expect(wrapper.instance().handleSubmit).toHaveBeenCalled()
  })

我得到一个类属性,该函数是类的一个实例,需要更新组件以注册该函数,但是看起来像组件 handleSubmit 函数被调用而不是模拟?

将 handleSubmit 交换为类函数作为方法使我可以访问类原型,该类原型在监视 Search.prototype 时通过了测试,但我真的很想获得类属性方法的解决方案。

所有建议和建议将不胜感激!

4个回答

我认为单元测试应该足够健壮以捕获error任何不受欢迎的代码更改的情况。

请在您的测试中包含严格的断言。

对于条件语句,也请覆盖分支。例如,在ifandelse语句的情况下,您将不得不编写two测试。

对于用户操作,您应该尝试模拟操作而不是手动调用函数。

请看下面的例子,

import React from 'react';
import { shallow } from 'enzyme';
import { SearchForm } from 'components/Search';


describe('Search Component', () => {
  let wrapper;
  const toggleAlert = jest.fn();
  const handleChange = jest.fn();
  const successAlert = {
    alertType: 'success',
    alertMessage: 'Success!!!'
  }
  const errorAlert = {
    alertType: 'error',
    alertMessage: 'Error!!!'
  }
  beforeEach(() => {
    wrapper = shallow(<SearchForm toggleAlert={toggleAlert} />);
  });
  it('"handleSubmit" to have been called with "mocky"', () => {
    expect(toggleAlert).not.toHaveBeenCalled();
    expect(handleChange).not.toHaveBeenCalled();
    wrapper.find('Input').simulate('change', { target: { value: 'mocky' } });
    expect(handleChange).toHaveBeenCalledTimes(1);
    expect(wrapper.state().searchTerm).toBe('mocky');
    wrapper.find('Button').simulate('click');
    expect(toggleAlert).toHaveBeenCalledTimes(1);
    expect(toggleAlert).toHaveBeenCalledWith(successAlert);
    expect(wrapper.state().searchTerm).toBe('');
  });

  it('"handleSubmit" to have been called with "other than mocky"', () => {
    expect(toggleAlert).not.toHaveBeenCalled();
    expect(handleChange).not.toHaveBeenCalled();
    wrapper.find('Input').simulate('change', { target: { value: 'Hello' } });
    expect(handleChange).toHaveBeenCalledTimes(1);
    expect(wrapper.state().searchTerm).toBe('Hello');
    wrapper.find('Button').simulate('click');
    expect(toggleAlert).toHaveBeenCalledTimes(1);
    expect(toggleAlert).toHaveBeenCalledWith(errorAlert);
    expect(wrapper.state().searchTerm).toBe('Hello');
  });
});

因此,我首先更新包装器实例,然后更新包装器,从而设法创建了一个有效的解决方案。测试现在有效。

工作测试看起来像:

it('should call handleSubmit function on submit', () => {
    const wrapper = shallow(<Search toggleAlert={jest.fn()} />)
    wrapper.instance().handleSubmit = jest.fn()
    wrapper.instance().forceUpdate()
    wrapper.update()
    wrapper.find('.btn').simulate('click')
    expect(wrapper.instance().handleSubmit).toHaveBeenCalled()
  })

尝试这样的事情

it('should call handleSubmit function on submit', () => {
        const toggleAlert = jest.fn();
        const wrapper = shallow(<Search toggleAlert={toggleAlert} />)
        wrapper.setState({ searchText: 'mocky' });
        wrapper.find('Button').at(0).simulate('click');
        expect(toggleAlert).toHaveBeenLastCalledWith({
                   alertType: 'success',
                   alertMessage: 'Success!!!'
              });
      })

****更新

 constructor(props) {
    super(props) //you have to add props to access it this.props

    this.state = {
      searchTerm: ''
    }

    this.handleSubmit = this.handleSubmit.bind(this)
  }

您不需要为此场景编写单元测试。您应该能够相信框架会触发您提供的正确处理程序。一个更有用的测试是模拟toggleAlertprop 并测试实例方法handleSubmit这是大多数自定义逻辑所在的位置,因此我们最有可能发现错误的位置。快照测试应该适用于渲染函数输出的任何部分。

该组件的合理测试套件类似于以下内容:

describe('handleSubmit', () => {
  let wrapper;
  let spy;

  describe('when searchTerm is "mocky"', () => {
    beforeEach(() => {
      spy = jest.fn();
      wrapper = shallow(<SearchForm toggleAlert={spy} />);
      wrapper.setState({ searchTerm: 'mocky' });
    });

    it('will fire spy with expected arguments', () => {
      // verify that spy has not been fired prior to test
      expect(spy).not.toBeCalled();

      wrapper.instance().handleSubmit();

      expect(spy).toBeCalled();
      expect(spy).toBeCalledWith({
        alertType: 'success',
        alertMessage: 'Success!!!'
      });
    });

    it('will set searchTerm to ""', () => {
      expect(wrapper.state('searchTerm')).toBe('mocky');
      wrapper.instance().handleSubmit();
      expect(wrapper.state('searchTerm')).toBe('');
    });
  });

  describe('when searchTerm is "something else"', () => {
    beforeEach(() => {
      spy = jest.fn();
      wrapper = shallow(<SearchForm toggleAlert={spy} />);
      wrapper.setState({ searchTerm: 'something else' });
    });

    it('will fire spy with expected arguments', () => {
      // verify that spy has not been fired prior to test
      expect(spy).not.toBeCalled();

      wrapper.instance().handleSubmit();

      expect(spy).toBeCalled();
      expect(spy).toBeCalledWith({
        alertType: 'error',
        alertMessage: 'Error!!!'
      });
    });
  });
});