test(proto-plus): add regression tests and guard descriptor check in marshal

Author: guptaarima

packages/proto-plus/proto/marshal/marshal.py

@@ -224,7 +224,8 @@ def to_proto(self, proto_type, value, *, strict: bool = False):
         # annotation. We need to do the conversion based on the `value`
         # field's type.
         if isinstance(value, dict) and (
-            proto_type.DESCRIPTOR.has_options
+            hasattr(proto_type, "DESCRIPTOR")
+            and proto_type.DESCRIPTOR.has_options
             and proto_type.DESCRIPTOR.GetOptions().map_entry
         ):
             recursive_type = type(proto_type().value)

packages/proto-plus/tests/test_message.py

@@ -500,3 +500,36 @@ class Arm(proto.Message):
 
 def test_dir_message_base():
     assert set(dir(proto.Message)) == set(dir(type))
+
+
+def test_invalid_initialization_type_error():
+    """Verify that bad types passed to __init__ raise a descriptive TypeError."""
+    class UserProfile(proto.Message):
+        username = proto.Field(proto.STRING, number=1)
+        age = proto.Field(proto.INT32, number=2)
+
+    with pytest.raises(TypeError) as excinfo:
+        # Passing a list where a string is expected
+        UserProfile(username=["not", "a", "string"])
+
+    error_msg = str(excinfo.value)
+    assert "Failed to initialize UserProfile" in error_msg
+    assert "Underlying error" in error_msg
+    assert isinstance(excinfo.value.__cause__, TypeError)
+
+
+def test_invalid_assignment_type_error():
+    """Verify that bad types assigned via __setattr__ raise a descriptive TypeError."""
+    class UserProfile(proto.Message):
+        username = proto.Field(proto.STRING, number=1)
+        age = proto.Field(proto.INT32, number=2)
+    profile = UserProfile()
+
+    with pytest.raises(TypeError) as excinfo:
+        # Assigning a dictionary where an integer is expected
+        profile.age = {"invalid": "type"}
+
+    error_msg = str(excinfo.value)
+    assert "Failed to set field 'age' on UserProfile" in error_msg
+    assert "{'invalid': 'type'}" in error_msg
+    assert isinstance(excinfo.value.__cause__, TypeError)