twilio.sugar.Model.PhoneAutomation.IncomingPhoneNumbers C# (CSharp) Method

        public IList<PhoneNumber> IncomingPhoneNumbers(String phoneNumber = "", String friendlyName = "")
        {
            _parameters.Clear();
            if (!String.IsNullOrEmpty(phoneNumber))
            {
                _parameters.Add("PhoneNumber", phoneNumber);
            }
            if (!String.IsNullOrEmpty(friendlyName))
            {
                _parameters.Add("FriendlyName", friendlyName);
            }

            _twilioResponse = _account.request(String.Format("Accounts/{0}/IncomingPhoneNumbers.json", _account.id), "GET", _parameters);
            dynamic data = ParseResponseData(_twilioResponse);

            IList<PhoneNumber> incomingPhoneNumbers = new List<PhoneNumber>();

            foreach (dynamic item in data.incoming_phone_numbers)
            {
                incomingPhoneNumbers.Add(new PhoneNumber
                {
                    sid = item.sid,
                    account_sid = item.account_sid,
                    friendly_name = item.friendly_name,
                    phone_number = item.phone_number,
                    voice_url = item.voice_url,
                    voice_method = item.voice_method,
                    voice_fallback_url = item.voice_fallback_url,
                    voice_fallback_method = item.voice_fallback_method,
                    voice_caller_id_lookup = Convert.ToBoolean(item.voice_caller_id_lookup),
                    date_created = !String.IsNullOrEmpty(item.date_created) ? Convert.ToDateTime(item.date_created) : null,
                    date_updated = !String.IsNullOrEmpty(item.date_updated) ? Convert.ToDateTime(item.date_updated) : null,
                    sms_url = item.sms_url,
                    sms_method = item.sms_method,
                    sms_fallback_url = item.sms_fallback_url,
                    sms_fallback_method = item.sms_fallback_method,
                    capabilities = new Capabilities
                    {
                        sms = item.capabilities.sms,
                        voice = item.capabilities.voice
                    },
                    status_callback = item.status_callback,
                    status_callback_method = item.status_callback_method,
                    api_version = item.api_version,
                    uri = item.uri
                });
            }

            return incomingPhoneNumbers;
        }

 public void IncomingPhoneNumbersWithNowParametersShouldThrowNullReferenceError()
 {
     try
     {
         var account = new TwilioAccountMock();
         var phoneAutomation = new PhoneAutomation(account);
         phoneAutomation.IncomingPhoneNumbers();
         Assert.Fail("Cannot call this method without params");
     }
     catch (System.Exception ex)
     {
         Assert.IsInstanceOfType(ex, typeof(System.ArgumentNullException));
         Assert.IsTrue(ex.Message.Contains("missing phoneNumber"));
     }
 }