Use nested tempfile fixture for cleanups

There are a couple places where we appear to leak tempfile and tempdirs
because we are creating dirs/files in the tests then not deleting them
when we are done. Address this by using the nested tempfile fixture
which will nest all tempfiles and tempdirs in a tempdir that the fixture
cleans up when the test is completed.

Change-Id: I2818ed48823c544bb1be6b4e1e58f78109197bc1

tests/unit/test_disk_accountant.py

@@ -10,6 +10,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import fixtures
 import os
 import tempfile
 import time
@@ -32,6 +33,10 @@ class FakeExecutor(object):
 
 
 class TestDiskAccountant(BaseTestCase):
+    def setUp(self):
+        super(TestDiskAccountant, self).setUp()
+        self.useFixture(fixtures.NestedTempfile())
+
     def test_disk_accountant(self):
         jobs_dir = tempfile.mkdtemp(
             dir=os.environ.get("ZUUL_TEST_ROOT", None))

tests/unit/test_encryption.py

@@ -12,6 +12,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import fixtures
 import os
 import subprocess
 import tempfile
@@ -26,6 +27,10 @@ class TestEncryption(BaseTestCase):
     def setUp(self):
         super(TestEncryption, self).setUp()
         self.private, self.public = encryption.generate_rsa_keypair()
+        # Because we set delete to False when using NamedTemporaryFile below
+        # we need to stick our usage of temporary files in the NestedTempfile
+        # fixture ensuring everything gets cleaned up when it is done.
+        self.useFixture(fixtures.NestedTempfile())
 
     def test_serialization(self):
         "Verify key serialization"