test_url_generation_with_proxy: do not use contextlib.nested()

This method does not exist in Python 3, use the "@mock.patch.object" decorator
instead.

Change-Id: Ic45fea1553320c61be284a9397b54fd32f7d30ef

ceilometerclient/tests/test_http.py

@@ -13,7 +13,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import contextlib
 import mock
 
 from ceilometerclient.common import http
@@ -47,21 +46,17 @@ class HttpClientTest(utils.BaseTestCase):
         client = http.HTTPClient(self.url)
         self.assertIsNotNone(client.get_connection())
 
-    def test_url_generation_with_proxy(self):
-        client = http.HTTPClient(self.url)
+    @mock.patch.object(http.HTTPClient, 'get_connection')
+    def test_url_generation_with_proxy(self, get_conn):
+        client = http.HTTPClient(self.url, token=lambda: 'token')
         client.proxy_url = "http://localhost:3128/"
         conn = mock.MagicMock()
-        with contextlib.nested(
-            mock.patch.object(client, 'get_connection'),
-            mock.patch.object(client, 'auth_token')
-        ) as (get_conn, auth_token):
-            conn.request.side_effect = Exception("stop")
-            get_conn.return_value = conn
-            auth_token.return_value = "token"
-            try:
-                client._http_request('/v1/resources', 'GET')
-            except Exception:
-                pass
+        conn.request.side_effect = Exception("stop")
+        get_conn.return_value = conn
+        try:
+            client._http_request('/v1/resources', 'GET')
+        except Exception:
+            pass
         conn.request.assert_called_once_with('GET', (self.url.rstrip('/') +
                                                      '/v1/resources'),
                                              headers=mock.ANY)