Capture test output better

This change adds some new classes to test.unit.utils which wrap up the
collection and mocking of the std err and std out.  This will make the
testing code easier to write and maintain.

Change-Id: I50ad2a736b2bb550ab83f6a43fb5a0fb5393573e

1 files changed, 72 insertions, 0 deletions

diff --git a/tests/unit/utils.py b/tests/unit/utils.py
index c149abf..3cbb160 100644
--- a/tests/unit/utils.py
+++ b/tests/unit/utils.py
@@ -12,11 +12,16 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import functools
+import sys
 from requests import RequestException
 from time import sleep
 import testtools
+import mock
+import six
 from six.moves import reload_module
 from swiftclient import client as c
+from swiftclient import shell as s
 
 
 def fake_get_auth_keystone(os_options, exc=None, **kwargs):
@@ -213,3 +218,70 @@ class MockHttpTest(testtools.TestCase):
     def tearDown(self):
         super(MockHttpTest, self).tearDown()
         reload_module(c)
+
+
+class CaptureStream(object):
+
+    def __init__(self, stream):
+        self.stream = stream
+        self._capture = six.StringIO()
+        self.streams = [self.stream, self._capture]
+
+    def write(self, *args, **kwargs):
+        for stream in self.streams:
+            stream.write(*args, **kwargs)
+
+    def writelines(self, *args, **kwargs):
+        for stream in self.streams:
+            stream.writelines(*args, **kwargs)
+
+    def getvalue(self):
+        return self._capture.getvalue()
+
+
+class CaptureOutput(object):
+
+    def __init__(self):
+        self._out = CaptureStream(sys.stdout)
+        self._err = CaptureStream(sys.stderr)
+
+        WrappedOutputManager = functools.partial(s.OutputManager,
+                                                 print_stream=self._out,
+                                                 error_stream=self._err)
+        self.patchers = [
+            mock.patch('swiftclient.shell.OutputManager',
+                       WrappedOutputManager),
+            mock.patch('sys.stdout', self._out),
+            mock.patch('sys.stderr', self._err),
+        ]
+
+    def __enter__(self):
+        for patcher in self.patchers:
+            patcher.start()
+        return self
+
+    def __exit__(self, *args, **kwargs):
+        for patcher in self.patchers:
+            patcher.stop()
+
+    @property
+    def out(self):
+        return self._out.getvalue()
+
+    @property
+    def err(self):
+        return self._err.getvalue()
+
+    # act like the string captured by stdout
+
+    def __str__(self):
+        return self.out
+
+    def __len__(self):
+        return len(self.out)
+
+    def __eq__(self, other):
+        return self.out == other
+
+    def __getattr__(self, name):
+        return getattr(self.out, name)