如何在describe或it块中使用jest.mock？

Question

我正在使用打字稿和玩笑。我有两个文件，users.service.ts，它导入 Producer.ts。我想模拟 Producer.ts 中的一个函数。这个效果很好

import { sendUserData } from './users.service';

const processDataSpy = jest.fn().mockImplementation(() => {
    throw new Error('failed');
  });

  jest.mock('../users/manager', () => ({
    sendEvent: async (arg1: string, arg2: string, arg3: any) =>
      processDataSpy(arg1, arg2, arg3),
  }));


describe('users.service', () => {

  it('invokes endpoint and returns proper data if unsuccessful', async () => {

    const result = await sendUserData(
      data
    );

    expect(result).toBe(false);

  });

但是，我想在 processDataSpy 中模拟不同的结果。我正在测试上面的情况并引发错误，但我想测试不引发错误的情况。如何测试多个案例？将“jest.mock”移动到“it”块内会破坏测试......

  it('invokes endpoint and returns proper data if unsuccessful', async () => {
    
    jest.mock('../users/manager', () => ({
      sendEvent: async (arg1: string, arg2: string, arg3: any) =>
        processDataSpy(arg1, arg2, arg3),
    }));
    ...
    const result = await sendUserData(
      data
    );

    expect(result).toBe(false);

  });

我收到一条错误消息，表明该模拟不再被使用或启动。如何在“describe”或“it”块中使用“jest.mock”？

Answer 1

您可以使用processDataSpy.mockImplementationinsideit或testblock。

// Optionally reset the mock before each test
beforeEach(() => {
  processDataSpy.mockReset(); 
});

it('Another use case', async () => {
    
    processDataSpy.mockImplementation(() => {
      throw new Error('Another error');
    })
   
    const result = await sendUserData(
      data
    );

    expect(result).toBe(false);
});