Question

Jest 错误“TypeError：无法读取未定义的属性‘preventDefault’”

2018-12-26

3173

javascript reactjs jestjs

我有一个如下所示的函数，当我要测试该函数时，出现了上述错误。

函数

toggleRecovery = e => {
    e.preventDefault()
    this.setState(
      {
        recovery: !this.state.recovery
      },
      () => {
        this.props.reset()
      }
    )
  }

测试

test('if the recovery state is true should set the state to the false', () => {
      wrapper.setState({ recovery: true })
      //Check if the state is true initially
      expect(wrapper.state().recovery).toBeTruthy()
      //Calling the toggleRecovery()
      wrapper.instance().toggleRecovery()
      expect(wrapper.state().recovery).toBeFalsy()
      expect(props.reset).toHaveBeenCalled()
    })

错误

TypeError: Cannot read property 'preventDefault' of undefined

我该如何克服这个错误以及导致上述错误的原因是什么

Answer 1

在实例上调用 toggleRecovery 时，您可以传递 preventDefault 模拟，例如

test('if the recovery state is true should set the state to the false', () => {
      wrapper.setState({ recovery: true })
      //Check if the state is true initially
      expect(wrapper.state().recovery).toBeTruthy()
      //Calling the toggleRecovery()
      wrapper.instance().toggleRecovery({ 
          preventDefault: () => {
      })
      expect(wrapper.state().recovery).toBeFalsy()
      expect(props.reset).toHaveBeenCalled()
    })