ci: Add output stream fixture to fix CI

Story: 2006642
Task: 36865

Change-Id: I1205f9fef26ec6aaa6858befddb27fb172b25318

magnum/tests/base.py

@@ -30,6 +30,7 @@ from magnum.common import keystone as magnum_keystone
 from magnum.objects import base as objects_base
 from magnum.tests import conf_fixture
 from magnum.tests import fake_notifier
+from magnum.tests import output_fixture
 from magnum.tests import policy_fixture
 
 
@@ -79,6 +80,8 @@ class TestCase(base.BaseTestCase):
 
         self.policy = self.useFixture(policy_fixture.PolicyFixture())
 
+        self.output = self.useFixture(output_fixture.OutputStreamCapture())
+
         self.useFixture(fixtures.MockPatchObject(
             oslo_messaging, 'Notifier',
             fake_notifier.FakeNotifier))

magnum/tests/output_fixture.py

@@ -0,0 +1,48 @@
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    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 fixtures
+import os
+
+_TRUE_VALUES = ('True', 'true', '1', 'yes')
+
+
+class OutputStreamCapture(fixtures.Fixture):
+    """Capture output streams during tests.
+
+    This fixture captures errant printing to stderr / stdout during
+    the tests and lets us see those streams at the end of the test
+    runs instead. Useful to see what was happening during failed
+    tests.
+    """
+    def setUp(self):
+        super(OutputStreamCapture, self).setUp()
+        if os.environ.get('OS_STDOUT_CAPTURE') in _TRUE_VALUES:
+            self.out = self.useFixture(fixtures.StringStream('stdout'))
+            self.useFixture(
+                fixtures.MonkeyPatch('sys.stdout', self.out.stream))
+        if os.environ.get('OS_STDERR_CAPTURE') in _TRUE_VALUES:
+            self.err = self.useFixture(fixtures.StringStream('stderr'))
+            self.useFixture(
+                fixtures.MonkeyPatch('sys.stderr', self.err.stream))
+
+    @property
+    def stderr(self):
+        return self.err._details["stderr"].as_text()
+
+    @property
+    def stdout(self):
+        return self.out._details["stdout"].as_text()

tox.ini

@@ -13,6 +13,8 @@ whitelist_externals = bash
 setenv =
    VIRTUAL_ENV={envdir}
    PYTHONWARNINGS=default::DeprecationWarning
+   OS_STDOUT_CAPTURE=1
+   OS_STDERR_CAPTURE=1
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 passenv = TEMPEST_* OS_TEST_*