System.Net.Http.Headers.AuthenticationHeaderValue.ToString C# (CSharp) Method

        public override string ToString()
        {
            if (string.IsNullOrEmpty(_parameter))
            {
                return _scheme;
            }
            return _scheme + " " + _parameter;
        }

        public void ToString_UseBothNoParameterAndSetParameter_AllSerializedCorrectly()
        {
            using (HttpResponseMessage response = new HttpResponseMessage())
            {
                string input = string.Empty;

                AuthenticationHeaderValue auth = new AuthenticationHeaderValue("Digest",
                    "qop=\"auth\",algorithm=MD5-sess,nonce=\"+Upgraded+v109e309640b\",charset=utf-8,realm=\"Digest\"");

                Assert.Equal(
                    "Digest qop=\"auth\",algorithm=MD5-sess,nonce=\"+Upgraded+v109e309640b\",charset=utf-8,realm=\"Digest\"",
                    auth.ToString());
                response.Headers.ProxyAuthenticate.Add(auth);
                input += auth.ToString();

                auth = new AuthenticationHeaderValue("Negotiate");
                Assert.Equal("Negotiate", auth.ToString());
                response.Headers.ProxyAuthenticate.Add(auth);
                input += ", " + auth.ToString();

                auth = new AuthenticationHeaderValue("Custom", ""); // empty string should be treated like 'null'.
                Assert.Equal("Custom", auth.ToString());
                response.Headers.ProxyAuthenticate.Add(auth);
                input += ", " + auth.ToString();

                string result = response.Headers.ProxyAuthenticate.ToString();
                Assert.Equal(input, result);
            }
        }