fix: handle the case when agent loading error doesn't have msg attribute in agent loader

PiperOrigin-RevId: 767447874

Author: seanzhougoogle

src/google/adk/cli/utils/agent_loader.py

@@ -76,7 +76,12 @@ def _load_from_module_or_package(
         e.msg = f"Fail to load '{agent_name}' module. " + e.msg
         raise e
     except Exception as e:
-      e.msg = f"Fail to load '{agent_name}' module. " + e.msg
+      if hasattr(e, "msg"):
+        e.msg = f"Fail to load '{agent_name}' module. " + e.msg
+        raise e
+      e.args = (
+          f"Fail to load '{agent_name}' module. {e.args[0] if e.args else ''}",
+      ) + e.args[1:]
       raise e
 
     return None
@@ -110,7 +115,15 @@ def _load_from_submodule(self, agent_name: str) -> Optional[BaseAgent]:
         e.msg = f"Fail to load '{agent_name}.agent' module. " + e.msg
         raise e
     except Exception as e:
-      e.msg = f"Fail to load '{agent_name}.agent' module. " + e.msg
+      if hasattr(e, "msg"):
+        e.msg = f"Fail to load '{agent_name}.agent' module. " + e.msg
+        raise e
+      e.args = (
+          (
+              f"Fail to load '{agent_name}.agent' module."
+              f" {e.args[0] if e.args else ''}"
+          ),
+      ) + e.args[1:]
       raise e
 
     return None

tests/unittests/cli/utils/test_agent_loader.py

@@ -351,7 +351,7 @@ def __init__(self):
       assert f"Fail to load '{agent_name}' module." in str(exc_info.value)
       assert "No module named 'non_existent_module'" in str(exc_info.value)
 
-  def test_agent_internal_import_error(self):
+  def test_agent_internal_syntax_error(self):
     """Test other import errors within an agent's code (e.g., SyntaxError)."""
     with tempfile.TemporaryDirectory() as temp_dir:
       temp_path = Path(temp_dir)
@@ -380,10 +380,47 @@ def __init__(self):
       ) as exc_info:  # Or potentially ImportError depending on Python version specifics with importlib
         loader.load_agent(agent_name)
 
-      assert f"Fail to load '{agent_name}' module." in str(exc_info.value)
+      assert str(exc_info.value).startswith(
+          f"Fail to load '{agent_name}' module."
+      )
       # Check for part of the original SyntaxError message
       assert "invalid syntax" in str(exc_info.value).lower()
 
+  def test_agent_internal_name_error(self):
+    """Test other import errors within an agent's code (e.g., SyntaxError)."""
+    with tempfile.TemporaryDirectory() as temp_dir:
+      temp_path = Path(temp_dir)
+      agent_name = "name_error_agent"
+
+      # Create agent with a syntax error (which leads to ImportError)
+      agent_file = temp_path / f"{agent_name}.py"
+      agent_file.write_text(dedent(f"""
+                from google.adk.agents.base_agent import BaseAgent
+
+                # name is not defined
+                print(non_existing_name)
+
+                class {agent_name.title()}Agent(BaseAgent):
+                    def __init__(self):
+                        super().__init__(name="{agent_name}")
+
+                root_agent = {agent_name.title()}Agent()
+            """))
+
+      loader = AgentLoader(str(temp_path))
+      # SyntaxError is a subclass of Exception, and importlib might wrap it
+      # The loader is expected to prepend its message and re-raise.
+      with pytest.raises(
+          NameError
+      ) as exc_info:  # Or potentially ImportError depending on Python version specifics with importlib
+        loader.load_agent(agent_name)
+
+      assert str(exc_info.value).startswith(
+          f"Fail to load '{agent_name}' module."
+      )
+      # Check for part of the original SyntaxError message
+      assert "is not defined" in str(exc_info.value).lower()
+
   def test_sys_path_modification(self):
     """Test that agents_dir is added to sys.path correctly."""
     with tempfile.TemporaryDirectory() as temp_dir: