fix(sqlalchemy-spanner): instantiate types from _type_map and fix black formatting

_designate_type() was returning type classes instead of instances,
causing isinstance() checks to fail. Handles the mixed _type_map
where most entries are classes but NUMERIC is already an instance
(with precision=38, scale=9). Also adds stacklevel=2 to the
unknown-type warning and reformats test_types.py to pass black.

Author: waiho-gumloop

packages/sqlalchemy-spanner/google/cloud/sqlalchemy_spanner/sqlalchemy_spanner.py

@@ -1248,11 +1248,13 @@ def _designate_type(self, str_repr):
             return _type_map["ARRAY"](inner_type)
         else:
             try:
-                return _type_map[str_repr]
+                col_type = _type_map[str_repr]
+                return col_type() if isinstance(col_type, type) else col_type
             except KeyError:
                 warnings.warn(
                     "Did not recognize Spanner type '%s', "
-                    "mapping it to NullType" % str_repr
+                    "mapping it to NullType" % str_repr,
+                    stacklevel=2,
                 )
                 return types.NullType()
 

packages/sqlalchemy-spanner/tests/unit/test_types.py

@@ -70,7 +70,10 @@ def test_in_type_map(self):
 
     def test_in_inverse_type_map(self):
         assert sqlalchemy_spanner.TOKENLIST in sqlalchemy_spanner._type_map_inv
-        assert sqlalchemy_spanner._type_map_inv[sqlalchemy_spanner.TOKENLIST] == "TOKENLIST"
+        assert (
+            sqlalchemy_spanner._type_map_inv[sqlalchemy_spanner.TOKENLIST]
+            == "TOKENLIST"
+        )
 
     def test_type_compiler_roundtrip(self):
         compiler = sqlalchemy_spanner.SpannerTypeCompiler(