Mock filecache.CACHE in unit tests

This mocks the global filecache.CACHE in unit tests that modify the
value. This is to avoid errors when other unit tests are running
at the same time, that use that same variable.

For example, ..unit.test_client.ClientTest.test_loader_arguments_token
has failed with  ...
    File "ironicclient/common/filecache.py", line 103, in retrieve_data
     data = _get_cache().get(key, expiration_time=expiry)
  AttributeError: 'int' object has no attribute 'get'

Change-Id: I84b9c6699c98d1fa642247808b6ddea4fae1e8d0

ironicclient/tests/unit/common/test_filecache.py

@@ -29,6 +29,7 @@ class FileCacheTest(utils.BaseTestCase):
         result = filecache._build_key(None, None)
         self.assertEqual('None:None', result)
 
+    @mock.patch.object(filecache, 'CACHE', None)
     @mock.patch.object(os.environ, 'get', autospec=True)
     @mock.patch.object(os.path, 'exists', autospec=True)
     @mock.patch.object(os, 'makedirs', autospec=True)
@@ -38,12 +39,12 @@ class FileCacheTest(utils.BaseTestCase):
         cache_val = 6
         # If not present in the env, get will return the defaulted value
         mock_get.return_value = filecache.DEFAULT_EXPIRY
-        filecache.CACHE = None
         mock_exists.return_value = False
         cache_region = mock.Mock(spec=dogpile.cache.region.CacheRegion)
         cache_region.configure.return_value = cache_val
         mock_makeregion.return_value = cache_region
         self.assertEqual(cache_val, filecache._get_cache())
+        self.assertEqual(cache_val, filecache.CACHE)
         mock_exists.assert_called_once_with(filecache.CACHE_DIR)
         mock_makedirs.assert_called_once_with(filecache.CACHE_DIR)
         mock_get.assert_called_once_with(filecache.CACHE_EXPIRY_ENV_VAR,
@@ -53,6 +54,7 @@ class FileCacheTest(utils.BaseTestCase):
             arguments=mock.ANY,
             expiration_time=filecache.DEFAULT_EXPIRY)
 
+    @mock.patch.object(filecache, 'CACHE', None)
     @mock.patch.object(os.environ, 'get', autospec=True)
     @mock.patch.object(os.path, 'exists', autospec=True)
     @mock.patch.object(os, 'makedirs', autospec=True)
@@ -62,12 +64,12 @@ class FileCacheTest(utils.BaseTestCase):
         cache_val = 5643
         cache_expiry = '78'
         mock_get.return_value = cache_expiry
-        filecache.CACHE = None
         mock_exists.return_value = False
         cache_region = mock.Mock(spec=dogpile.cache.region.CacheRegion)
         cache_region.configure.return_value = cache_val
         mock_makeregion.return_value = cache_region
         self.assertEqual(cache_val, filecache._get_cache())
+        self.assertEqual(cache_val, filecache.CACHE)
         mock_get.assert_called_once_with(filecache.CACHE_EXPIRY_ENV_VAR,
                                          mock.ANY)
         cache_region.configure.assert_called_once_with(
@@ -75,6 +77,7 @@ class FileCacheTest(utils.BaseTestCase):
             arguments=mock.ANY,
             expiration_time=int(cache_expiry))
 
+    @mock.patch.object(filecache, 'CACHE', None)
     @mock.patch.object(filecache.LOG, 'warning', autospec=True)
     @mock.patch.object(os.environ, 'get', autospec=True)
     @mock.patch.object(os.path, 'exists', autospec=True)
@@ -86,12 +89,12 @@ class FileCacheTest(utils.BaseTestCase):
         cache_val = 5643
         cache_expiry = 'Rollenhagen'
         mock_get.return_value = cache_expiry
-        filecache.CACHE = None
         mock_exists.return_value = False
         cache_region = mock.Mock(spec=dogpile.cache.region.CacheRegion)
         cache_region.configure.return_value = cache_val
         mock_makeregion.return_value = cache_region
         self.assertEqual(cache_val, filecache._get_cache())
+        self.assertEqual(cache_val, filecache.CACHE)
         mock_get.assert_called_once_with(filecache.CACHE_EXPIRY_ENV_VAR,
                                          mock.ANY)
         cache_region.configure.assert_called_once_with(
@@ -103,13 +106,13 @@ class FileCacheTest(utils.BaseTestCase):
                     'env_var': filecache.CACHE_EXPIRY_ENV_VAR}
         mock_log.assert_called_once_with(mock.ANY, log_dict)
 
+    @mock.patch.object(filecache, 'CACHE', 5552368)
     @mock.patch.object(os.path, 'exists', autospec=True)
     @mock.patch.object(os, 'makedirs', autospec=True)
     def test__get_cache_dir_already_exists(self, mock_makedirs, mock_exists):
-        cache_val = 5552368
         mock_exists.return_value = True
-        filecache.CACHE = cache_val
+        self.assertEqual(5552368, filecache._get_cache())
-        self.assertEqual(cache_val, filecache._get_cache())
+        self.assertEqual(5552368, filecache.CACHE)
         self.assertEqual(0, mock_exists.call_count)
         self.assertEqual(0, mock_makedirs.call_count)