反應，如何模擬單元測試的用戶輸入？

Question

我一直在嘗試單元測試一個反應組件，它接受用戶輸入。更具體地說，我試圖在反應組件中測試onChange函數。然而，我似乎無法設置輸入值，我嘗試了在互聯網上建議的幾種不同的方式，但似乎沒有任何工作。下面是我試圖測試的組件。

class Input extends Component { 
    constructor(props) { 
    super(props); 
    this.state = {value: ''}; 
    this.handleChange = this.handleChange.bind(this); 
    } 

    handleChange(event) { 
    /* Check if max length has been set. If max length has been 
    set make sure the user input is less than max Length, otherwise 
    return before updating the text string. */ 
    if(this.props.maxLength) { 
     if(event.target.value.length > this.props.maxLength) { 
     return; 
     } 
    } 
    this.setState({ value: event.target.value }); 
    } 

    render() { 
    const { disabled, label, maxLength, multiline, type, value, ...others} = this.props; 
    const theme = themeable(others.theme); 

    let inputClassName = classNames({ 
     "input": type !== 'checkbox', 
     "checkbox": type == 'checkbox', 
     disabled, 
     multiline, 
     value, 
     [`${this.props.className}`]: !!this.props.className 
    }); 

    return (
     <div {...theme(1, 'container')}> 
     {this.props.label ? <label htmlFor={this.props.htmlFor} {...theme(2, 'label')}>{label}</label> : null} 
      <input value={this.state.value} {...theme(3, ...inputClassName)} onChange={this.handleChange} type={type} /> 
     </div> 
    ); 
    } 
} 

我發現這個問題：https://github.com/airbnb/enzyme/issues/76，並試圖向底部的建議，我不斷收到未定義或空字符串。我嘗試了levibuzolic使用酶的模擬變化的建議，這可以在下面看到。然而，這只是返回AssertionError: expected '' to equal 'abcdefghij'

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    result.find('input').simulate('change', {target: {value: 'abcdefghijk'}}); 
    expect(result.state().value).to.equal("abcdefghij"); 
}); 

然後我試圖takkyuuplayer的建議，這也是下面。這也將失敗，並AssertionError: expected '' to equal 'abcdefghij'

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    result.find('input').node.value = 'abcdefghijk'; 
    expect(result.state().value).to.equal("abcdefghij"); 
    }); 

我發現這篇文章：https://medium.com/javascript-inside/testing-in-react-getting-off-the-ground-5f569f3088a#.f4gcjbaak和嘗試他們的方式也失敗了。

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    let input = result.find('input'); 
    input.get(0).value = 'abcdefghijk'; 
    input.simulate('change'); 
    expect(result.state().value).to.equal("abcdefghij"); 
    }); 

最後我試圖使用由Simulating text entry with reactJs TestUtils所建議的反應測試utils的，下面是我嘗試的代碼，但是這並沒有與錯誤消息：TypeError: Cannot read property '__reactInternalInstance$z78dboxwwtrznrmuut6wjc3di' of undefined

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    let input = result.find('input'); 
    TestUtils.Simulate.change(input, { target: { value: 'abcdefghijk' } }); 
    expect(result.state().value).to.equal("abcdefghij"); 
    }); 

那麼如何一個模擬用戶輸入所以他們可以測試onChange函數？

Answer 1

您的輸入組件中似乎有一個錯誤。當event.target.value.length > this.props.maxLength您從未設置實際狀態，將state.value作爲''。你似乎認爲它已被設置爲該值，但被截斷爲maxLength。你需要補充的是自己：

handleChange(event) { 
    /* Check if max length has been set. If max length has been 
    set make sure the user input is less than max Length, otherwise 
    return before updating the text string. */ 
    if (this.props.maxLength) { 
    if (event.target.value.length > this.props.maxLength) { 
     // ** Truncate value to maxLength 
     this.setState({ value: event.target.value.substr(0, this.props.maxLength) }); 
     return; 
    } 
    } 
    this.setState({ value: event.target.value }); 
} 

...那麼，下面的測試工作，並通過：

it('Make sure inputted text is shorter than max length',() => { 
    const result = mount(<Input maxLength={10}></Input>); 
    result.find('input').simulate('change', { target: { value: '1234567890!!!' } }); 
    expect(result.state().value).to.equal("1234567890"); 
});