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

Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
Change-Id: I5877aa495486ba28519b51d800c0474fd72859a5

heat/tests/common.py

@@ -82,9 +82,11 @@ class HeatTestCase(testscenarios.WithScenarios,
 
     def setUp(self, mock_keystone=True, mock_resource_policy=True,
               quieten_logging=True, mock_find_file=True):
-        super(HeatTestCase, self).setUp()
+        super().setUp()
         self.setup_logging(quieten=quieten_logging)
-        self.warnings = self.useFixture(fixtures.WarningsCapture())
+
+        self.useFixture(utils.WarningsFixture())
+
         scheduler.ENABLE_SLEEP = False
         self.useFixture(fixtures.MonkeyPatch(
             'heat.common.exception._FATAL_EXCEPTION_FORMAT_ERRORS',

heat/tests/utils.py

@@ -14,12 +14,14 @@
 import random
 import string
 import uuid
+import warnings
 
 import fixtures
 from oslo_config import cfg
 from oslo_db import options
 from oslo_serialization import jsonutils
 import sqlalchemy
+from sqlalchemy import exc as sqla_exc
 
 from heat.common import context
 from heat.db.sqlalchemy import api as db_api
@@ -235,6 +237,112 @@ class ForeignKeyConstraintFixture(fixtures.Fixture):
             self.addCleanup(disable_fks)
 
 
+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)
+
+        # Enable deprecation warnings for heat itself to capture upcoming
+        # SQLAlchemy changes
+
+        warnings.filterwarnings(
+            'ignore',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'error',
+            module='heat',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        # ...but filter everything out until we get around to fixing them
+        # TODO(stephenfin): Fix all of these
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message=r'The Engine.execute\(\) method is considered legacy ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message='The current statement is being autocommitted using ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message='Using strings to indicate column or relationship paths ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message=r'The Query.get\(\) method is considered legacy ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message='The Session.transaction attribute is considered legacy ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message='The Session.begin.subtransactions flag is deprecated ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message='The autoload parameter is deprecated ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message='The ``bind`` argument for schema methods that invoke ',
+            category=sqla_exc.SADeprecationWarning,
+        )
+
+        warnings.filterwarnings(
+            'ignore',
+            module='heat',
+            message=r'The legacy calling style of select\(\) is deprecated ',
+            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='heat',
+            category=sqla_exc.SAWarning,
+        )
+
+        self.addCleanup(self._reset_warning_filters)
+
+    def _reset_warning_filters(self):
+        warnings.filters[:] = self._original_warning_filters
+
+
 class AnyInstance(object):
     """Comparator for validating allowed instance type."""
 

tox.ini

@@ -5,9 +5,11 @@ minversion = 3.18.0
 
 [testenv]
 basepython = python3
-setenv = VIRTUAL_ENV={envdir}
-         PYTHONWARNINGS=default::DeprecationWarning
-         OS_TEST_PATH=heat/tests
+setenv =
+  OS_TEST_PATH=heat/tests
+  PYTHONDONTWRITEBYTECODE=1
+# TODO(stephenfin): Remove once we bump our upper-constraint to SQLAlchemy 2.0
+  SQLALCHEMY_WARN_20=1
 usedevelop = True
 deps = -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
        -r{toxinidir}/requirements.txt