模拟带有TypeScript的forwardRef组件嘲笑mockImplementation

问题描述

当组件包装在forwardRef中时，您应该如何处理测试文件中的模拟组件？ mockImplementation不在方法上，而是在属性渲染器上。

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...>>>'.

我理解为什么我得到类型错误的原因，因为ocker.mockImplementation是未定义的，但是如何正确推断类型呢？

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]
      }
    }

解决方法

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