test cleanup: Use oslotest's CaptureOutput fixture

Nova had its own copy of oslotest's CaptureOutput fixture called
OutputStreamCapture (probably predating the oslotest one, actually). DRY
it up.

A future change should be able to remove references to this fixture from
nova.test.TestCase by inheriting from oslotest.base.BaseTestCase instead
of testtools.TestCase. But we may or may not want to do the same for
TestOSAPIFixture since that would pull in fixtures we don't care about
(timeout and tempfile/tempdir).

Change-Id: I18a5d621c9e414452852d4aeb0379be0d30af5df

nova/test.py

@@ -47,6 +47,7 @@ from oslo_utils import timeutils
 from oslo_versionedobjects import fixture as ovo_fixture
 from oslotest import mock_fixture
 from oslotest import moxstubout
+from oslotest import output
 from oslotest import timeout
 import six
 from six.moves import builtins
@@ -188,8 +189,7 @@ class TestCase(testtools.TestCase):
         self.useFixture(fixtures.TempHomeDir())
         self.useFixture(log_fixture.get_logging_handle_error_fixture())
 
-        self.output = nova_fixtures.OutputStreamCapture()
-        self.useFixture(self.output)
+        self.output = self.useFixture(output.CaptureOutput())
 
         self.stdlog = nova_fixtures.StandardLogging()
         self.useFixture(self.stdlog)

nova/tests/fixtures.py

@@ -203,34 +203,6 @@ class StandardLogging(fixtures.Fixture):
         self.logger._output.truncate(0)
 
 
-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()
-
-
 class DatabasePoisonFixture(fixtures.Fixture):
     def setUp(self):
         super(DatabasePoisonFixture, self).setUp()

nova/tests/unit/test_fixtures.py

@@ -15,7 +15,6 @@
 # under the License.
 
 import copy
-import sys
 
 import fixtures as fx
 import futurist
@@ -26,6 +25,7 @@ from oslo_log import log as logging
 from oslo_utils.fixture import uuidsentinel as uuids
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
+from oslotest import output
 import sqlalchemy
 import testtools
 
@@ -88,25 +88,6 @@ class TestConfFixture(testtools.TestCase):
         self._test_override()
 
 
-class TestOutputStream(testtools.TestCase):
-    """Ensure Output Stream capture works as expected.
-
-    This has the added benefit of providing a code example of how you
-    can manipulate the output stream in your own tests.
-    """
-    def test_output(self):
-        self.useFixture(fx.EnvironmentVariable('OS_STDOUT_CAPTURE', '1'))
-        self.useFixture(fx.EnvironmentVariable('OS_STDERR_CAPTURE', '1'))
-
-        out = self.useFixture(fixtures.OutputStreamCapture())
-        sys.stdout.write("foo")
-        sys.stderr.write("bar")
-        self.assertEqual("foo", out.stdout)
-        self.assertEqual("bar", out.stderr)
-        # TODO(sdague): nuke the out and err buffers so it doesn't
-        # make it to testr
-
-
 class TestLogging(testtools.TestCase):
     def test_default_logging(self):
         stdlog = self.useFixture(fixtures.StandardLogging())
@@ -150,7 +131,7 @@ class TestOSAPIFixture(testtools.TestCase):
     @mock.patch('nova.objects.Service.create')
     def test_responds_to_version(self, mock_service_create, mock_get):
         """Ensure the OSAPI server responds to calls sensibly."""
-        self.useFixture(fixtures.OutputStreamCapture())
+        self.useFixture(output.CaptureOutput())
         self.useFixture(fixtures.StandardLogging())
         self.useFixture(conf_fixture.ConfFixture())
         self.useFixture(fixtures.RPCFixture('nova.test'))