Replace use of Engine.scalar()

Resolve the following RemovedIn20Warning warning:

  The Engine.scalar() method is considered legacy as of the 1.x series
  of SQLAlchemy and will be removed in 2.0. All statement execution in
  SQLAlchemy 2.0 is performed by the Connection.execute() method of
  Connection, or in the ORM by the Session.execute() method of Session;
  the Result.scalar() method can then be used to return a scalar result.

Change-Id: Ic3c9c5bb008b6299f2ed9a59bda0329fab9d554d
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

2 files changed, 12 insertions, 7 deletions

diff --git a/oslo_db/tests/sqlalchemy/test_exc_filters.py b/oslo_db/tests/sqlalchemy/test_exc_filters.py
index 9075f2a..a05c9a9 100644
--- a/oslo_db/tests/sqlalchemy/test_exc_filters.py
+++ b/oslo_db/tests/sqlalchemy/test_exc_filters.py
@@ -1162,11 +1162,14 @@ class TestDBDisconnected(TestsExceptionFilter):
                 yield
 
     def _test_ping_listener_disconnected(
-            self, dialect_name, exc_obj, is_disconnect=True):
+        self, dialect_name, exc_obj, is_disconnect=True,
+    ):
         with self._fixture(dialect_name, exc_obj, 1, is_disconnect):
             conn = self.engine.connect()
             with conn.begin():
-                self.assertEqual(1, conn.scalar(sqla.select(1)))
+                self.assertEqual(
+                    1, conn.execute(sqla.select(1)).scalars().first(),
+                )
                 self.assertFalse(conn.closed)
                 self.assertFalse(conn.invalidated)
                 self.assertTrue(conn.in_transaction())
@@ -1179,7 +1182,9 @@ class TestDBDisconnected(TestsExceptionFilter):
 
         # test implicit execution
         with self._fixture(dialect_name, exc_obj, 1):
-            self.assertEqual(1, self.engine.scalar(sqla.select(1)))
+            self.assertEqual(
+                1, self.engine.execute(sqla.select(1)).scalars().first(),
+            )
 
     def test_mariadb_error_1927(self):
         for code in [1927]:
diff --git a/oslo_db/tests/sqlalchemy/test_sqlalchemy.py b/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
index ede67c6..003a49a 100644
--- a/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
+++ b/oslo_db/tests/sqlalchemy/test_sqlalchemy.py
@@ -479,14 +479,14 @@ class SQLiteConnectTest(test_base.BaseTestCase):
         engine = self._fixture(sqlite_fk=True)
         self.assertEqual(
             1,
-            engine.scalar(sql.text('pragma foreign_keys'))
+            engine.execute(sql.text('pragma foreign_keys')).scalars().first(),
         )
 
         engine = self._fixture(sqlite_fk=False)
 
         self.assertEqual(
             0,
-            engine.scalar(sql.text("pragma foreign_keys"))
+            engine.execute(sql.text('pragma foreign_keys')).scalars().first(),
         )
 
     def test_sqlite_synchronous_listener(self):
@@ -496,14 +496,14 @@ class SQLiteConnectTest(test_base.BaseTestCase):
         # http://www.sqlite.org/pragma.html#pragma_synchronous
         self.assertEqual(
             2,
-            engine.scalar(sql.text('pragma synchronous'))
+            engine.execute(sql.text('pragma synchronous')).scalars().first(),
         )
 
         engine = self._fixture(sqlite_synchronous=False)
 
         self.assertEqual(
             0,
-            engine.scalar(sql.text('pragma synchronous'))
+            engine.execute(sql.text('pragma synchronous')).scalars().first(),
         )