tests: Enable SQLAlchemy 2.0 deprecation warnings

Well, sort of. We enable them but immediately filter out the ones we're
actually seeing, the rationale being that we can address these in a
piecemeal fashion without the risk of introducing new issues.

There's a lot more to be done here. However, the work done in oslo.db
[1], nova [2], cinder [2] etc. should provide a guide for how to resolve
the outstanding issues.

[1] https://review.opendev.org/q/topic:sqlalchemy-20+project:openstack/oslo.db
[2] https://review.opendev.org/q/topic:sqlalchemy-20+project:openstack/nova
[3] https://review.opendev.org/q/topic:sqlalchemy-20+project:openstack/cinder

Change-Id: I5b11e63451b0e76969421fa8fe39ac2b920f90ab
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

taskflow/test.py

@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 #    Copyright (C) 2012 Yahoo! Inc. All Rights Reserved.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -26,6 +24,7 @@ from testtools import matchers
 from testtools import testcase
 
 from taskflow import exceptions
+from taskflow.tests import fixtures as taskflow_fixtures
 from taskflow.tests import utils
 from taskflow.utils import misc
 
@@ -92,6 +91,10 @@ class ItemsEqual(object):
 class TestCase(base.BaseTestCase):
     """Test case base class for all taskflow unit tests."""
 
+    def setUp(self):
+        super().setUp()
+        self.useFixture(taskflow_fixtures.WarningsFixture())
+
     def makeTmpDir(self):
         t_dir = self.useFixture(fixtures.TempDir())
         return t_dir.path

taskflow/tests/fixtures.py

@@ -0,0 +1,65 @@
+# 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()
+
+        self._original_warning_filters = warnings.filters[:]
+
+        warnings.simplefilter('once', DeprecationWarning)
+
+        # The UUIDFields emits a warning if the value is not a valid UUID.
+        # Let's escalate that to an exception in the test to prevent adding
+        # violations.
+
+        warnings.filterwarnings('error', message='.*invalid UUID.*')
+
+        # Enable deprecation warnings for taskflow itself to capture upcoming
+        # SQLAlchemy changes
+        warnings.filterwarnings(
+            'ignore',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'error',
+            module='taskflow',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            message='The current statement is being autocommitted',
+            module='taskflow',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        # Enable general SQLAlchemy warnings also to ensure we're not doing
+        # silly stuff. It's possible that we'll need to filter things out here
+        # with future SQLAlchemy versions, but that's a good thing
+        warnings.filterwarnings(
+            'error',
+            module='taskflow',
+            category=sqla_exc.SAWarning,
+        )
+        self.addCleanup(self._reset_warning_filters)
+
+    def _reset_warning_filters(self):
+        warnings.filters[:] = self._original_warning_filters

tox.ini

@@ -1,11 +1,11 @@
 [tox]
-minversion = 3.1.0
+minversion = 3.18.0
 envlist = cover,docs,pep8,py3,pylint,update-states
-ignore_basepython_conflict = True
 
 [testenv]
-basepython = python3
 setenv =
+# TODO(stephenfin): Remove once we bump our upper-constraint to SQLAlchemy 2.0
+  SQLALCHEMY_WARN_20=1
 # We need to install a bit more than just `test' because those drivers have
 # custom tests that we always run
 deps =