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>

oslo_db/sqlalchemy/utils.py

@@ -31,7 +31,6 @@ from sqlalchemy import Boolean
 from sqlalchemy import CheckConstraint
 from sqlalchemy import Column
 from sqlalchemy.engine import Connectable
-from sqlalchemy.engine import reflection
 from sqlalchemy.engine import url as sa_url
 from sqlalchemy import exc
 from sqlalchemy import func
@@ -578,12 +577,16 @@ def _change_deleted_column_type_to_boolean_sqlite(engine, table_name,
                 column_copy = _get_not_supported_column(col_name_col_instance,
                                                         column.name)
             else:
-                column_copy = column.copy()
+                # FIXME(stephenfin): We shouldn't be using this private API;
+                # figure out how else to copy an arbitrary column schema
+                column_copy = column._copy()
         else:
             column_copy = Column('deleted', Boolean, default=0)
         columns.append(column_copy)
 
-    constraints = [constraint.copy() for constraint in table.constraints]
+    # FIXME(stephenfin): We shouldn't be using this private API;
+    # figure out how else to copy an arbitrary column schema
+    constraints = [constraint._copy() for constraint in table.constraints]
 
     meta = table.metadata
     new_table = Table(table_name + "__tmp__", meta,
@@ -652,15 +655,15 @@ def _is_deleted_column_constraint(constraint):
 
 def _change_deleted_column_type_to_id_type_sqlite(engine, table_name,
                                                   **col_name_col_instance):
-    # NOTE(boris-42): sqlaclhemy-migrate can't drop column with check
-    #                 constraints in sqlite DB and our `deleted` column has
-    #                 2 check constraints. So there is only one way to remove
-    #                 these constraints:
-    #                 1) Create new table with the same columns, constraints
-    #                 and indexes. (except deleted column).
-    #                 2) Copy all data from old to new table.
-    #                 3) Drop old table.
-    #                 4) Rename new table to old table name.
+    # NOTE(boris-42): sqlalchemy-migrate can't drop column with check
+    # constraints in sqlite DB and our `deleted` column has two check
+    # constraints. There is only one way to remove these constraints:
+    #
+    # 1) Create new table with the same columns, constraints and indexes.
+    #    (except deleted column).
+    # 2) Copy all data from old to new table.
+    # 3) Drop old table.
+    # 4) Rename new table to old table name.
     meta = MetaData(bind=engine)
     table = Table(table_name, meta, autoload=True)
     default_deleted_value = _get_default_deleted_value(table)
@@ -673,7 +676,9 @@ def _change_deleted_column_type_to_id_type_sqlite(engine, table_name,
                 column_copy = _get_not_supported_column(col_name_col_instance,
                                                         column.name)
             else:
-                column_copy = column.copy()
+                # FIXME(stephenfin): We shouldn't be using this private API;
+                # figure out how else to copy an arbitrary column schema
+                column_copy = column._copy()
         else:
             column_copy = Column('deleted', table.c.id.type,
                                  default=default_deleted_value)
@@ -682,7 +687,9 @@ def _change_deleted_column_type_to_id_type_sqlite(engine, table_name,
     constraints = []
     for constraint in table.constraints:
         if not _is_deleted_column_constraint(constraint):
-            constraints.append(constraint.copy())
+            # FIXME(stephenfin): We shouldn't be using this private API;
+            # figure out how else to copy an arbitrary constraint schema
+            constraints.append(constraint._copy())
 
     new_table = Table(table_name + "__tmp__", meta,
                       *(columns + constraints))
@@ -734,7 +741,7 @@ def get_indexes(engine, table_name):
     :param table_name: name of the table
     """
 
-    inspector = reflection.Inspector.from_engine(engine)
+    inspector = sqlalchemy.inspect(engine)
     indexes = inspector.get_indexes(table_name)
     return indexes
 

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())

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)

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: