https://www.npmjs.com/package/certnames包启发了我，然后我发现我可以直接用捆绑的tls模块来做，因为证书是通过tls层传输的，所以我们不需要发出http请求来获得它。

import * as tls from 'tls';

test('test', function (done) {
  let host = 'httpbin.org';
  let socket = tls.connect({
    port:443, 
    host,
    servername: host, // this is required in case the server enabled SNI
  }, () => {
    let x509Certificate = socket.getPeerX509Certificate();

    expect(x509Certificate.subject).toBe('CN=httpbin.org');

    done();
  });
});