return if the batch is empty

Author: Mohamed Zenadi

googleapiclient/http.py

@@ -1288,6 +1288,9 @@ def execute(self, http=None):
       httplib2.HttpLib2Error if a transport error has occured.
       googleapiclient.errors.BatchError if the response is the wrong format.
     """
+    # If we have no requests return
+    if len(self._order) == 0:
+      return None
 
     # If http is not supplied use the first valid one given in the requests.
     if http is None:

tests/test_http.py

@@ -766,6 +766,11 @@ def test_add_fail_for_resumable(self):
     self.request1.resumable = upload
     self.assertRaises(BatchError, batch.add, self.request1, request_id='1')
 
+  def test_execute_empty_batch_no_http(self):
+    batch = BatchHttpRequest()
+    ret = batch.execute()
+    self.assertEqual(None, ret)
+
   def test_execute(self):
     batch = BatchHttpRequest()
     callbacks = Callbacks()