[OpenAI] Fix tool_choice=required streaming when output has trailing extra data (#31610)

Signed-off-by: maylikenoother <ogedengbemary19@gmail.com>
Co-authored-by: Chauncey <chaunceyjiang@gmail.com>

tests/tool_use/test_tool_choice_required.py

@@ -311,6 +311,7 @@ def test_streaming_output_valid(output, empty_params, delta_len):
         previous_text = current_text
 
     assert len(messages) > 0
+
     combined_messages = "["
     for message in messages:
         if message.tool_calls[0].function.name:
@@ -328,3 +329,35 @@ def test_streaming_output_valid(output, empty_params, delta_len):
     combined_messages += "}]"
     assert json.loads(combined_messages) == output
     assert json.dumps(json.loads(combined_messages)) == output_json
+
+
+def test_streaming_output_valid_with_trailing_extra_data():
+    self = MagicMock()
+
+    output = [{"name": "get_current_weather", "parameters": {"city": "Vienna"}}]
+    output_json = json.dumps(output) + "\nDONE"
+
+    previous_text = ""
+    function_name_returned = False
+    messages = []
+    delta_len = 3
+    for i in range(0, len(output_json), delta_len):
+        delta_text = output_json[i : i + delta_len]
+        current_text = previous_text + delta_text
+
+        delta_message, function_name_returned = (
+            OpenAIServingChat.extract_tool_call_required_streaming(
+                self,
+                previous_text=previous_text,
+                current_text=current_text,
+                delta_text=delta_text,
+                function_name_returned=function_name_returned,
+            )
+        )
+
+        if delta_message:
+            messages.append(delta_message)
+
+        previous_text = current_text
+
+    assert len(messages) > 0