使用promise的Sinonjs测试方法

function fetchData() {
  return new Promise((resolve, reject) => {
    // 异步操作，比如从服务器获取数据
    setTimeout(() => {
      const data = 'Some data';
      resolve(data);
    }, 1000);
  });
}

function processData() {
  return fetchData().then(data => {
    // 处理数据
    return data.toUpperCase();
  });
}

const sinon = require('sinon');

describe('processData', () => {
  it('should process data correctly', () => {
    const fetchDataStub = sinon.stub().resolves('Some data');
    sinon.replace(global, 'fetchData', fetchDataStub);

    return processData().then(result => {
      // 验证处理后的数据是否正确
      expect(result).to.equal('SOME DATA');
    });
  });
});