jest.fn() 被多次调用

Question

我正在用jest和酶测试我的反应原生应用程序组件。为了监视作为道具传递的函数，我正在使用jest.fn().当我运行测试时，我收到错误说Expected mock function to have been called one time, but it was called two times。测试onPress方法时出现此错误。

我尝试删除在我的组件中调用 prop 方法的匿名函数; 直接引用组件内部<TouchableOpacity/> onPress方法，而无需从组件的 prop 调用它;在测试用例之前重新渲染测试组件。但没有成功。

/*BackButton.js*/
import React from 'react';
import { TouchableOpacity } from 'react-native';
import { Icon } from 'expo';
import { iconStyle, Colors } from '../constants';
const styles = {
    icon: {
        marginLeft: 5,
        color: Colors.white,
        fontSize: 40
    }
};
function BackButton(props) {
    return (
        <TouchableOpacity
         onPress={()=>props.navigate()}
         style={{width: 50}}
        >
            <Icon.Ionicons
             name={`${iconStyle}-refresh`}
             style={styles.icon}
            />
        </TouchableOpacity>
    );
 }
 export default BackButton;
=======================================
/*BackButton-test.js*/
import 'react-native';
import React from 'react';
import {mount} from 'enzyme';
import BackButton from '../BackButton';
describe('navigate action', () => {
    const spy = jest.fn();
    const wrapper = mount(<BackButton navigate={spy}/>);
    it('renders correctly', () => {
        expect(wrapper).toMatchSnapshot();
    });
    beforeEach(() => {
       wrapper.prop('navigate')();
    });
    it('calls once', () => {
       expect(spy).toHaveBeenCalledTimes(1);
    });
 });

而且，当我直接在beforeEach里面打电话spy()时，它也被叫了2次。

Answer 1

从beforeEach()函数中取出wrapper.prop('navigate')

您的beforeEach()正在运行的次数是it()