使用jest模拟在typescript测试中从另一个文件调用的函数

/project
  /src
    - main.ts
    - utils.ts
  /tests
    - main.test.ts
  - tsconfig.json
  - jest.config.js
  - package.json

// src/utils.ts
export const fetchData = async (): Promise<string> => {
  // Simulate an API call
  return "real data";
};

// src/main.ts
import { fetchData } from './utils';

export const getData = async (): Promise<string> => {
  const data = await fetchData();
  return `Processed ${data}`;
};

npm install --save-dev jest ts-jest @types/jest

module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
  moduleNameMapper: {
    '^src/(.*)$': '<rootDir>/src/$1',
  },
};

// tests/main.test.ts
import { getData } from '../src/main';
import * as utils from '../src/utils';

jest.mock('../src/utils');

describe('getData', () => {
  it('should return processed data', async () => {
    // Mock the fetchData function
    const mockFetchData = jest.spyOn(utils, 'fetchData').mockResolvedValue('mock data');

    const result = await getData();

    expect(result).toBe('Processed mock data');

    // Restore the original implementation
    mockFetchData.mockRestore();
  });
});

npm test