fix(dbapi): autocommit enabling fails if no transactions begun

google/cloud/spanner_dbapi/connection.py

@@ -82,7 +82,13 @@ def autocommit(self, value):
         :type value: bool
         :param value: New autocommit mode state.
         """
-        if value and not self._autocommit:
+        if (
+            value
+            and not self._autocommit
+            and self._transaction
+            and not self._transaction.committed
+            and not self._transaction.rolled_back
+        ):
             self.commit()
 
         self._autocommit = value

tests/unit/spanner_dbapi/test_connection.py

@@ -15,7 +15,6 @@
 """Cloud Spanner DB-API Connection class unit tests."""
 
 import mock
-import sys
 import unittest
 import warnings
 
@@ -51,25 +50,57 @@ def _make_connection(self):
         database = instance.database(self.DATABASE)
         return Connection(instance, database)
 
-    @unittest.skipIf(sys.version_info[0] < 3, "Python 2 patching is outdated")
-    def test_property_autocommit_setter(self):
-        from google.cloud.spanner_dbapi import Connection
-
-        connection = Connection(self.INSTANCE, self.DATABASE)
+    def test_autocommit_setter_transaction_not_started(self):
+        connection = self._make_connection()
 
         with mock.patch(
             "google.cloud.spanner_dbapi.connection.Connection.commit"
         ) as mock_commit:
             connection.autocommit = True
-            mock_commit.assert_called_once_with()
-            self.assertEqual(connection._autocommit, True)
+            mock_commit.assert_not_called()
+            self.assertTrue(connection._autocommit)
 
         with mock.patch(
             "google.cloud.spanner_dbapi.connection.Connection.commit"
         ) as mock_commit:
             connection.autocommit = False
             mock_commit.assert_not_called()
-            self.assertEqual(connection._autocommit, False)
+            self.assertFalse(connection._autocommit)
+
+    def test_autocommit_setter_transaction_started(self):
+        connection = self._make_connection()
+
+        with mock.patch(
+            "google.cloud.spanner_dbapi.connection.Connection.commit"
+        ) as mock_commit:
+            connection._transaction = mock.Mock(committed=False, rolled_back=False)
+
+            connection.autocommit = True
+            mock_commit.assert_called_once()
+            self.assertTrue(connection._autocommit)
+
+    def test_autocommit_setter_transaction_started_commited_rolled_back(self):
+        connection = self._make_connection()
+
+        with mock.patch(
+            "google.cloud.spanner_dbapi.connection.Connection.commit"
+        ) as mock_commit:
+            connection._transaction = mock.Mock(committed=True, rolled_back=False)
+
+            connection.autocommit = True
+            mock_commit.assert_not_called()
+            self.assertTrue(connection._autocommit)
+
+        connection.autocommit = False
+
+        with mock.patch(
+            "google.cloud.spanner_dbapi.connection.Connection.commit"
+        ) as mock_commit:
+            connection._transaction = mock.Mock(committed=False, rolled_back=True)
+
+            connection.autocommit = True
+            mock_commit.assert_not_called()
+            self.assertTrue(connection._autocommit)
 
     def test_property_database(self):
         from google.cloud.spanner_v1.database import Database