tests: Enable SADeprecationWarning warnings

Highlight use of deprecated SQLAlchemy APIs to ensure we keep on top of
things. This requires resolving the following SADeprecationWarning
warnings:

  The from_engine() method on Inspector is deprecated and will be
  removed in a future release.  Please use the sqlalchemy.inspect()
  function on an Engine or Connection in order to acquire an Inspector.

  The Column.copy() method is deprecated and will be removed in a future
  release.

  The ColumnCollectionConstraint.copy() method is deprecated and will be
  removed in a future release.

There are more warnings to be resolved related to SQLAlchemy 2.0, but
those require a special environment option (SQLALCHEMY_WARN_20) to
trigger and a lot of work to resolve. We'll address those in a series of
follow-ups.

Change-Id: I34b395e6d50f4e4151178c327d94308e6f5d5b6e
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

3 files changed, 41 insertions, 2 deletions

diff --git a/oslo_db/tests/base.py b/oslo_db/tests/base.py
index 8d15666..a74ef82 100644
--- a/oslo_db/tests/base.py
+++ b/oslo_db/tests/base.py
@@ -12,6 +12,8 @@
 
 from oslotest import base
 
+from oslo_db.tests import fixtures
+
 
 class BaseTestCase(base.BaseTestCase):
     """Test case base class for all oslo.db unit tests."""
@@ -19,3 +21,5 @@ class BaseTestCase(base.BaseTestCase):
     def setUp(self):
         """Run before each test method to initialize test environment."""
         super().setUp()
+
+        self.warning_fixture = self.useFixture(fixtures.WarningsFixture())
diff --git a/oslo_db/tests/fixtures.py b/oslo_db/tests/fixtures.py
new file mode 100644
index 0000000..c08a34d
--- /dev/null
+++ b/oslo_db/tests/fixtures.py
@@ -0,0 +1,36 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import warnings
+
+import fixtures
+from sqlalchemy import exc as sqla_exc
+
+
+class WarningsFixture(fixtures.Fixture):
+    """Filters out warnings during test runs."""
+
+    def setUp(self):
+        super().setUp()
+        # Make deprecation warnings only happen once to avoid spamming
+        warnings.simplefilter('once', DeprecationWarning)
+
+        warnings.filterwarnings(
+            'error', message='Evaluating non-mapped column expression',
+            category=sqla_exc.SAWarning)
+
+        # Enable deprecation warnings to capture upcoming SQLAlchemy changes
+        warnings.filterwarnings(
+            'error',
+            category=sqla_exc.SADeprecationWarning)
+
+        self.addCleanup(warnings.resetwarnings)
diff --git a/oslo_db/tests/sqlalchemy/test_utils.py b/oslo_db/tests/sqlalchemy/test_utils.py
index b86faf0..47d587d 100644
--- a/oslo_db/tests/sqlalchemy/test_utils.py
+++ b/oslo_db/tests/sqlalchemy/test_utils.py
@@ -24,7 +24,6 @@ from sqlalchemy import CheckConstraint
 from sqlalchemy import MetaData, Table, Column
 from sqlalchemy import ForeignKey, ForeignKeyConstraint
 from sqlalchemy.dialects.postgresql import psycopg2
-from sqlalchemy.engine import reflection
 from sqlalchemy.engine import url as sa_url
 from sqlalchemy.exc import OperationalError
 from sqlalchemy.ext.declarative import declarative_base
@@ -796,7 +795,7 @@ class TestMigrationUtils(db_test_base._DbTestCase):
         utils.change_deleted_column_type_to_id_type(self.engine, table_name)
         utils.change_deleted_column_type_to_boolean(self.engine, table_name)
 
-        insp = reflection.Inspector.from_engine(self.engine)
+        insp = sqlalchemy.inspect(self.engine)
         real_indexes = insp.get_indexes(table_name)
         self.assertEqual(3, len(real_indexes))
         for index in real_indexes: