How can I test HTTPS endpoints in go?

So I'm trying to mock out a response to an https request using httptest.TLSServer but the http.Client making the request keeps telling me that the server is giving an invalid http response. I bet this is because there's no actual SSL cert. Is there any way I can get the client to ignore tls while still mocking out an https request?

The test code in question

func TestFacebookLogin(t *testing.T) {
	db := glob.db
	server := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		resp := `
		{
		  "id": "123",
		  "email": "blah",
		  "first_name": "Ben",
		  "last_name": "Botwin"
		}
		`

		w.Write([]byte(resp))
	}))
	defer server.Close()

	transport := &http.Transport{
		Proxy: func(r *http.Request) (*url.URL, error) {
			return url.Parse(server.URL)
		},
	}

	svc := userService{db: db, client: &http.Client{Transport: transport}}

	_, err := svc.FacebookLogin("asdf")

	if err != nil {
		t.Errorf("Error found: %s", err)
	}

}

And the request that I'm trying to make:

url := "https://<Some facebook api endpoint>"
req, err := http.NewRequest("GET", url, nil)
resp, err := client.Do(req)
if err != nil {
	return nil, err
}
defer resp.Body.Close()

The test server uses a self signed certificate. There are two ways to avoid errors. The first is to use an HTTP client configured with the test server's certificates:

certs := x509.NewCertPool()
for _, c := range server.TLS.Certificates {
	roots, err := x509.ParseCertificates(c.Certificate[len(c.Certificate)-1])
	if err != nil {
		log.Fatalf("error parsing server's root cert: %v", err)
	}
	for _, root := range roots {
		certs.AddCert(root)
	}
}
client := http.Client{
	Transport: &http.Transport{
		TLSClientConfig: &tls.Config{
			RootCAs: certs,
		},
	},
}

playground example

An easier option is to skip cert verification:

client := http.Client{
	Transport: &http.Transport{
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true,
		},
	},
}

playground example

There's an additional issue. The client expects to connect to a proxy server, but the it's actually connecting to the test server directly. Try hooking the dial function instead of the proxy:

client := http.Client{
	Transport: &http.Transport{
        Dial: func(network, addr string) (net.Conn, error) {
            return net.Dial("tcp", server.URL[strings.LastIndex(server.URL, "/")+1:])
        },
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true,
		},
	},
}

playground example

You just need to use the http client provided by the test server:

httpClient := server.Client()