Update test to match new parallel_tool_calls behavior

Changed test_prepare_options_removes_parallel_tool_calls_when_no_tools to
test_prepare_options_preserves_parallel_tool_calls_when_no_tools to reflect
that parallel_tool_calls is now preserved even when no tools are present,
consistent with the tool_choice behavior.

Author: eavanvalkenburg

python/packages/core/tests/openai/test_openai_chat_client.py

@@ -890,17 +890,17 @@ def test_multiple_function_calls_in_single_message(openai_unit_test_env: dict[st
     assert prepared[0]["tool_calls"][1]["id"] == "call_2"
 
 
-def test_prepare_options_removes_parallel_tool_calls_when_no_tools(openai_unit_test_env: dict[str, str]) -> None:
-    """Test that parallel_tool_calls is removed when no tools are present."""
+def test_prepare_options_preserves_parallel_tool_calls_when_no_tools(openai_unit_test_env: dict[str, str]) -> None:
+    """Test that parallel_tool_calls is preserved even when no tools are present."""
     client = OpenAIChatClient()
 
     messages = [ChatMessage(role="user", text="test")]
     options = {"allow_multiple_tool_calls": True}
 
     prepared_options = client._prepare_options(messages, options)
 
-    # Should not have parallel_tool_calls when no tools
-    assert "parallel_tool_calls" not in prepared_options
+    # parallel_tool_calls is preserved even when no tools (consistent with tool_choice behavior)
+    assert prepared_options.get("parallel_tool_calls") is True
 
 
 async def test_streaming_exception_handling(openai_unit_test_env: dict[str, str]) -> None: