TO SQUASH: Make dict a global.

oauth2client/client.py

@@ -113,6 +113,7 @@
 _GCE_METADATA_URI = 'http://169.254.169.254'
 _METADATA_FLAVOR_HEADER = 'metadata-flavor'  # lowercase header
 _DESIRED_METADATA_FLAVOR = 'Google'
+_GCE_HEADERS = {_METADATA_FLAVOR_HEADER: _DESIRED_METADATA_FLAVOR}
 
 # Expose utcnow() at module level to allow for
 # easier testing (by replacing with a stub).
@@ -1000,10 +1001,9 @@ def _detect_gce_environment():
     #       the metadata resolution was particularly slow. The latter case is
     #       "unlikely".
     http = transport.get_http_object(timeout=GCE_METADATA_TIMEOUT)
-    headers = {_METADATA_FLAVOR_HEADER: _DESIRED_METADATA_FLAVOR}
     try:
         response, _ = transport.request(
-            http, _GCE_METADATA_URI, headers=headers)
+            http, _GCE_METADATA_URI, headers=_GCE_HEADERS)
         return (
             response.status == http_client.OK and
             response.get(_METADATA_FLAVOR_HEADER) == _DESIRED_METADATA_FLAVOR)

tests/test_client.py

@@ -40,9 +40,6 @@
 
 
 DATA_DIR = os.path.join(os.path.dirname(__file__), 'data')
-METADATA_HEADERS = {
-    client._METADATA_FLAVOR_HEADER: client._DESIRED_METADATA_FLAVOR,
-}
 
 
 def assertUrisEqual(testcase, expected, actual):
@@ -362,7 +359,7 @@ def _environment_check_gce_helper(self, status_ok=True,
                                       server_software=''):
         if status_ok:
             headers = {'status': http_client.OK}
-            headers.update(METADATA_HEADERS)
+            headers.update(client._GCE_HEADERS)
         else:
             headers = {'status': http_client.NOT_FOUND}
 
@@ -389,7 +386,7 @@ def _environment_check_gce_helper(self, status_ok=True,
                     self.assertEqual(http.uri, client._GCE_METADATA_URI)
                     self.assertEqual(http.method, 'GET')
                     self.assertIsNone(http.body)
-                    self.assertEqual(http.headers, METADATA_HEADERS)
+                    self.assertEqual(http.headers, client._GCE_HEADERS)
                 else:
                     new_http.assert_not_called()
                     self.assertEqual(http.requests, 0)
@@ -415,7 +412,7 @@ def test_environment_check_gce_timeout(self, mock_request, new_http):
         new_http.assert_called_once_with(timeout=client.GCE_METADATA_TIMEOUT)
         mock_request.assert_called_once_with(
             new_http.return_value, client._GCE_METADATA_URI,
-            headers=METADATA_HEADERS)
+            headers=client._GCE_HEADERS)
 
     def test_environ_check_gae_module_unknown(self):
         with mock_module_import('google.appengine'):