如何在Angular中正确测试setInterval()内的语句？

业务代码 #

public async authenticate(username: string, password: string) {
    const authenticationResponse = await this.dataProvider.authenticate(username, password);

    if (authenticationResponse.result.code == 0) {
        //start interval for periodically checking authentication info
        this._authInfoIntervalId = setInterval(() => {
             this.getAuthInfo();
        }, 2000);
}

问题说明 #

单元测试中，唯独this.getAuthInfo()这一行未被覆盖，尝试用jasmine.createSpy相关方法但没效果，求正确的测试实现方式。

失败的测试尝试 #

it('should test interval somehow', () => {
  const intervalCallback = jasmine.createSpy("getAuthInfo");
  jasmine.clock().install();
  service.authenticate('username', 'password');
  jasmine.clock().tick(2001);
  expect(intervalCallback).toHaveBeenCalled();
})

测试失败提示：AuthenticationService should test interval somehow FAILED Expected spy getAuthInfo to have been called.

正确解决方案 #

需要先对dataProvider.authenticate进行Spy，让它返回符合条件的响应（使代码能进入interval逻辑分支），同时Spy目标服务的getAuthInfo方法，再配合异步处理和Jasmine时钟推进：

it('should test interval somehow', async () => {
    const intervalCallback = spyOn(service, 'getAuthInfo');
    spyOn(dataProvider, 'authenticate').and.returnValue(Promise.resolve(authenticateMockResponse));
    jasmine.clock().install();
    await service.authenticate('username', 'password');
    jasmine.clock().tick(2001);
    expect(intervalCallback).toHaveBeenCalled();
});

内容的提问来源于stack exchange，提问作者Raadush