Shift EnvironmentVariable fixture setup to base

While investigating a different branch, I came across a test failure
due to the ROOT_DISK environment variable leaking into a test. The
CMDEnvironmentTest already had code to deal with that case, added to
deal with the same problem affecting it, so I moved the code into
the base module so all tests can benefit.

Change-Id: I7e82584f75a309c4cea6fb3f7c0c420358c778e1

os_cloud_config/cmd/utils/tests/test_environment.py

@@ -13,7 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import fixtures
 import mock
 import testtools
 
@@ -24,13 +23,6 @@ from os_cloud_config.tests import base
 
 class CMDEnviromentTest(base.TestCase):
 
-    def setUp(self):
-        super(CMDEnviromentTest, self).setUp()
-        for key in ('OS_AUTH_URL', 'OS_PASSWORD', 'OS_TENANT_NAME',
-                    'OS_USERNAME', 'OS_CACERT'):
-            fixture = fixtures.EnvironmentVariable(key)
-            self.useFixture(fixture)
-
     @mock.patch.dict('os.environ', {})
     def test_ensure_environment_missing_all(self):
         message = ("OS_AUTH_URL, OS_PASSWORD, OS_TENANT_NAME, OS_USERNAME "

os_cloud_config/tests/base.py

@@ -51,3 +51,8 @@ class TestCase(testtools.TestCase):
             self.useFixture(fixtures.MonkeyPatch('sys.stderr', stderr))
 
         self.log_fixture = self.useFixture(fixtures.FakeLogger())
+
+        for key in ('OS_AUTH_URL', 'OS_PASSWORD', 'OS_TENANT_NAME',
+                    'OS_USERNAME', 'OS_CACERT', 'ROOT_DISK'):
+            fixture = fixtures.EnvironmentVariable(key)
+            self.useFixture(fixture)