如何在Angular/Jasmine中测试Filereader.onload回调函数？

function mockFileReaderOnLoad(event) {
  // 在这里编写模拟的回调函数逻辑
}

spyOn(window, 'mockFileReaderOnLoad');

const mockFileReader = jasmine.createSpyObj('FileReader', ['readAsDataURL']);
mockFileReader.onload = mockFileReaderOnLoad;

const mockFile = new File(['file content'], 'filename.txt', { type: 'text/plain' });

const component = new YourComponent(mockFileReader);

component.readFile(mockFile);

expect(mockFileReaderOnLoad).toHaveBeenCalled();

describe('YourComponent', () => {
  let mockFileReader;
  let component;

  beforeEach(() => {
    mockFileReader = jasmine.createSpyObj('FileReader', ['readAsDataURL']);
    mockFileReader.onload = mockFileReaderOnLoad; // 定义模拟的回调函数
    component = new YourComponent(mockFileReader); // 创建Component实例，并注入模拟的FileReader对象
  });

  it('should call the FileReader onload callback', () => {
    const mockFile = new File(['file content'], 'filename.txt', { type: 'text/plain' });
    component.readFile(mockFile); // 调用Component中的方法，传入模拟的File对象
    expect(mockFileReaderOnLoad).toHaveBeenCalled(); // 断言模拟的回调函数被调用
  });
});