fix: Django and SQLAlchemy APIs are failing to use rowcount (#654)

* fix: Django and SQLAlchemy APIs are failing to use rowcount

* lint fix

Co-authored-by: Vikash Singh <[email protected]>

Author: Ilya Gurov

google/cloud/spanner_dbapi/cursor.py

@@ -14,7 +14,6 @@
 
 """Database cursor for Google Cloud Spanner DB API."""
 
-import warnings
 from collections import namedtuple
 
 import sqlparse
@@ -137,15 +136,11 @@ def description(self):
     def rowcount(self):
         """The number of rows produced by the last `execute()` call.
 
-        :raises: :class:`NotImplemented`.
+        The property is non-operational and always returns -1. Request
+        resulting rows are streamed by the `fetch*()` methods and
+        can't be counted before they are all streamed.
         """
-        warnings.warn(
-            "The `rowcount` property is non-operational. Request "
-            "resulting rows are streamed by the `fetch*()` methods "
-            "and can't be counted before they are all streamed.",
-            UserWarning,
-            stacklevel=2,
-        )
+        return -1
 
     @check_not_closed
     def callproc(self, procname, args=None):

tests/unit/spanner_dbapi/test_cursor.py

@@ -61,19 +61,11 @@ def test_property_description(self):
         self.assertIsNotNone(cursor.description)
         self.assertIsInstance(cursor.description[0], ColumnInfo)
 
-    @mock.patch("warnings.warn")
-    def test_property_rowcount(self, warn_mock):
+    def test_property_rowcount(self):
         connection = self._make_connection(self.INSTANCE, self.DATABASE)
         cursor = self._make_one(connection)
 
-        cursor.rowcount
-        warn_mock.assert_called_once_with(
-            "The `rowcount` property is non-operational. Request "
-            "resulting rows are streamed by the `fetch*()` methods "
-            "and can't be counted before they are all streamed.",
-            UserWarning,
-            stacklevel=2,
-        )
+        assert cursor.rowcount == -1
 
     def test_callproc(self):
         from google.cloud.spanner_dbapi.exceptions import InterfaceError