使用 typescript 模拟 forwardRef 组件 jest mockImplementation

Posted 2023-03-13

【中文标题】使用 typescript 模拟 forwardRef 组件 jest mockImplementation

【英文标题】：Mock forwardRef components jest mockImplementation with typescript

【发布时间】：2021-01-03 12:54:25

【问题描述】：

当组件被包裹在 forwardRef 中时，您打算如何处理测试文件中的模拟组件？ mockImplementation 不在方法上，而是在属性渲染上。

import React from 'react';
import Component from './Component';
import mocked from 'ts-jest/utils'

jest.mock('./Component');

const mockComponent(Component);

mockComponent.mockImplementation(() => <></>) /* this returns type error that mockImplementation is not a function */

mockComponent.render.mockImplementation(() => <></>) /* this works but get a typescript error */

我看到的打字稿错误是

TS2339: Property 'render' does not exist on type 'MockedFunction   "li", >, "button" | "slot" | "style" | "title" | "className" | "classes" | "innerRef" | "selected" | "dense" | "key" | "value" | "defaultChecked" | ... 261 more ... | "focusVisibleClassName"> & RefAttributes...>>>'.

我明白为什么会收到类型错误，因为 mockComponent.mockImplementation 是未定义的，但是如何正确推断出类型？

模拟显示为

      '$$typeof': Symbol(react.forward_ref),
      render: [Function: mockConstructor] 
        _isMockFunction: true,
        getMockImplementation: [Function],
        mock: [Getter/Setter],
        mockClear: [Function],
        mockReset: [Function],
        mockRestore: [Function],
        mockReturnValueOnce: [Function],
        mockResolvedValueOnce: [Function],
        mockRejectedValueOnce: [Function],
        mockReturnValue: [Function],
        mockResolvedValue: [Function],
        mockRejectedValue: [Function],
        mockImplementationOnce: [Function],
        mockImplementation: [Function],
        mockReturnThis: [Function],
        mockName: [Function],
        getMockName: [Function]
      
    

【参考方案1】：

import React from 'react';
// Asuming Component is a default exported component
import * as Component from './Component';

jest.mock('./Component');
const MockComponent = jest.fn(() => <div />);

jest.spyOn(Component.default.type, 'render').mockImplementation(MockLaneMarkup);

//now you can test if the MockComponent has beenCalled