Update topenAIChat.m

Add test for openAIChat/generate with default NVP values

Author: vpapanasta

tests/topenAIChat.m

@@ -38,6 +38,11 @@ function generateAcceptsMessagesAsInput(testCase)
             testCase.verifyWarningFree(@()generate(chat,messages));
         end
 
+        function generateOpenAIChatWithDefaultNVPValues(testCase)
+            chat = openAIChat();
+            testCase.verifyWarningFree(@()generate(chat,"This is okay"));
+        end
+
         function keyNotFound(testCase)
             testCase.verifyError(@()openAIChat, "llms:keyMustBeSpecified");
         end