Refresh empty OAuth2 credentials in batch request

Batch request serialization requires the credentials in the http
object to be applied to every individual request *prior* to
actually invoking http.request(). This circumvents the self-refresh
logic in the request() function monkey-patched by the OAuth2
credentials, thus resulting in the use of an uninitialized credentials
object.

The fix here is to detect when OAuth2-like credentials are being
used and to force a refresh in case the access token is not
initialized yet.

Resolves: #211

Author: Garciat

googleapiclient/http.py

@@ -1394,6 +1394,14 @@ def execute(self, http=None):
     if http is None:
       raise ValueError("Missing a valid http object.")
 
+    # Special case for OAuth2Credentials-style objects which have not yet been
+    # refreshed with an initial access_token.
+    if getattr(http.request, 'credentials', None) is not None:
+      creds = http.request.credentials
+      if not getattr(creds, 'access_token', None):
+        LOGGER.info('Attempting refresh to obtain initial access_token')
+        creds.refresh(http)
+
     self._execute(http, self._order, self._requests)
 
     # Loop over all the requests and check for 401s. For each 401 request the

tests/test_http.py

@@ -1072,6 +1072,34 @@ def test_execute_request_body(self):
       header = parts[1].splitlines()[1]
       self.assertEqual('Content-Type: application/http', header)
 
+  def test_execute_initial_refresh_oauth2(self):
+    batch = BatchHttpRequest()
+    callbacks = Callbacks()
+    cred = MockCredentials('Foo')
+
+    # Pretend this is a OAuth2Credentials object
+    cred.access_token = None
+
+    http = HttpMockSequence([
+      ({'status': '200',
+        'content-type': 'multipart/mixed; boundary="batch_foobarbaz"'},
+       BATCH_SINGLE_RESPONSE),
+    ])
+
+    cred.authorize(http)
+
+    batch.add(self.request1, callback=callbacks.f)
+    batch.execute(http=http)
+
+    self.assertEqual({'foo': 42}, callbacks.responses['1'])
+    self.assertIsNone(callbacks.exceptions['1'])
+
+    self.assertEqual(1, cred._refreshed)
+
+    self.assertEqual(1, cred._authorized)
+
+    self.assertEqual(1, cred._applied)
+
   def test_execute_refresh_and_retry_on_401(self):
     batch = BatchHttpRequest()
     callbacks = Callbacks()