fix: #2951 warn for tool name character replacement (#2953)

Author: seratch

src/agents/util/_transforms.py

@@ -4,18 +4,16 @@
 
 
 def transform_string_function_style(name: str) -> str:
-    # Replace spaces with underscores
-    name = name.replace(" ", "_")
+    transformed_name = name.replace(" ", "_")
 
-    # Replace non-alphanumeric characters with underscores
-    transformed_name = re.sub(r"[^a-zA-Z0-9_]", "_", name)
+    transformed_name = re.sub(r"[^a-zA-Z0-9_]", "_", transformed_name)
+    final_name = transformed_name.lower()
 
     if transformed_name != name:
-        final_name = transformed_name.lower()
         logger.warning(
             f"Tool name {name!r} contains invalid characters for function calling and has been "
             f"transformed to {final_name!r}. Please use only letters, digits, and underscores "
             "to avoid potential naming conflicts."
         )
 
-    return transformed_name.lower()
+    return final_name

tests/test_transforms.py

@@ -0,0 +1,43 @@
+import logging
+
+import pytest
+
+from agents.util._transforms import transform_string_function_style
+
+
+@pytest.mark.parametrize(
+    ("name", "transformed"),
+    [
+        ("My Tool", "my_tool"),
+        ("My-Tool", "my_tool"),
+    ],
+)
+def test_transform_string_function_style_warns_for_replaced_characters(
+    caplog: pytest.LogCaptureFixture,
+    name: str,
+    transformed: str,
+) -> None:
+    with caplog.at_level(logging.WARNING, logger="openai.agents"):
+        assert transform_string_function_style(name) == transformed
+
+    assert f"Tool name {name!r} contains invalid characters" in caplog.text
+    assert f"transformed to {transformed!r}" in caplog.text
+
+
+@pytest.mark.parametrize(
+    ("name", "transformed"),
+    [
+        ("MyTool", "mytool"),
+        ("transfer_to_Agent", "transfer_to_agent"),
+        ("snake_case", "snake_case"),
+    ],
+)
+def test_transform_string_function_style_does_not_warn_for_case_only_changes(
+    caplog: pytest.LogCaptureFixture,
+    name: str,
+    transformed: str,
+) -> None:
+    with caplog.at_level(logging.WARNING, logger="openai.agents"):
+        assert transform_string_function_style(name) == transformed
+
+    assert caplog.records == []