private static void CheckInvalidGetAuthenticationLength(string input, int startIndex)
        {
            object result = null;

            Assert.Equal(0, AuthenticationHeaderValue.GetAuthenticationLength(input, startIndex, out result));
            Assert.Null(result);
        }
        private static void CallGetAuthenticationLength(string input, int startIndex, int expectedLength,
                                                        AuthenticationHeaderValue expectedResult)
        {
            object result = null;

            Assert.Equal(expectedLength, AuthenticationHeaderValue.GetAuthenticationLength(input, startIndex, out result));
            Assert.Equal(expectedResult, result);
        }