reformat message

bindings/python/pymongoarrow/types.py

@@ -288,8 +288,8 @@ def _normalize_typeid(typeid, field_name):
             fields.append((sub_field_name, _normalize_typeid(sub_typeid, sub_field_name)))
         return struct(fields)
     if isinstance(typeid, list):
-        if len(typeid) == 0 or len(typeid) > 1:
-            msg = "Please provide a one datatype or struct in case of multiple datatypes in a list"
+        if len(typeid) != 1:
+            msg = f"list field in schema must contain exactly one element, not {len(typeid)}"
             raise ValueError(msg)
         return list_(_normalize_typeid(typeid[0], "0"))
     if _is_typeid_supported(typeid):

bindings/python/test/test_schema.py

@@ -108,7 +108,7 @@ def test_py_list_projection(self):
 
     def test_py_list_with_multiple_fields_raises(self):
 
-        with pytest.raises(ValueError, match="Please provide a one datatype or struct in case of multiple datatypes in a list"):
+        with pytest.raises(ValueError, match="list field in schema must contain exactly one element, not 2"):
             _ = Schema(
                 {
                     "_id": ObjectId, 
@@ -118,7 +118,7 @@ def test_py_list_with_multiple_fields_raises(self):
 
     def test_py_empty_list_raises(self):
 
-        with pytest.raises(ValueError, match="Please provide a one datatype or struct in case of multiple datatypes in a list"):
+        with pytest.raises(ValueError, match="list field in schema must contain exactly one element, not 0"):
             _ = Schema(
                 {
                     "_id": ObjectId,