Add a testing fixture to capture outputs during test runs

And use the new fixture for all Election tests

Change-Id: I3b431f33f5f47db0e755670e4a5ef971dfdc8d04

openstack_election/tests/fixtures.py

@@ -0,0 +1,48 @@
+# 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.
+
+from __future__ import absolute_import
+from __future__ import print_function
+from __future__ import unicode_literals
+
+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()

openstack_election/tests/test_utils.py

@@ -16,10 +16,19 @@ from __future__ import unicode_literals
 
 import testtools
 
+from openstack_election.tests import fixtures as election_fixtures
 import openstack_election.utils
 
 
-class TestGerritUtils(testtools.TestCase):
+class ElectionTestCase(testtools.TestCase):
+    def setUp(self):
+        """Run before each test method to initialize test environment."""
+        super(ElectionTestCase, self).setUp()
+        self.output = election_fixtures.OutputStreamCapture()
+        self.useFixture(self.output)
+
+
+class TestGerritUtils(ElectionTestCase):
     def test_candidate_files(self):
         review = {'revisions': {
                   'Ifake': {

test-requirements.txt

@@ -10,3 +10,4 @@ mock>=2.0.0 # BSD
 oslotest>=1.10.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testresources>=2.0.0 # Apache-2.0/BSD
+fixtures>=3.0.0 # Apache-2.0/BSD