APIClient::item_iterator: reset query_parameters after returning all items

The item_iterator method uses a query parameter called `since` to get the next
results from the API resource when the previous response includes a hasMore=True
property.

The problem here is the last API call leaves the query parameter defined to a
value related to the previous resource retrieved, and if you use the same api
client to iterate over different resources (i.e. campaigns), the results will
always be affected by the previous call.

Author: ricardofontanelli

tests.py

@@ -1,4 +1,5 @@
 import logging
+from unittest.mock import call
 import requests
 import usabilla as ub
 
@@ -124,18 +125,41 @@ def test_item_iterator(self):
         items = ['one', 'two', 'three', 'four']
         has_more = {'hasMore': True, 'items': items[:2], 'lastTimestamp': 1400000000001}
         no_more = {'hasMore': False, 'items': items[2:], 'lastTimestamp': 1400000000002}
+
         self.client.set_query_parameters = Mock()
         self.client.send_signed_request = Mock(side_effect=[has_more, no_more])
+
         index = 0
         for item in self.client.item_iterator('/some/url'):
             self.assertEqual(item, items[index])
             index += 1
-        self.client.set_query_parameters.assert_called_with({'since': 1400000000002})
+
+        self.client.set_query_parameters.assert_any_call({'since': 1400000000001})
+        self.client.set_query_parameters.assert_any_call({'since': 1400000000002})
+        self.client.set_query_parameters.assert_any_call({})
         self.assertEqual(self.client.send_signed_request.call_count, 2)
+
         self.client.send_signed_request.side_effect = requests.exceptions.HTTPError('mocked error')
         with self.assertRaises(requests.exceptions.HTTPError):
             list(self.client.item_iterator('/some/url'))
 
+    def test_item_iterator_resets_query_parameters_after_returning_all_items(self):
+        first_response = {'hasMore': True, 'items': [1], 'lastTimestamp': 1400000000001}
+        second_response = {'hasMore': False, 'items': [2], 'lastTimestamp': 1400000000002}
+        third_response = {'hasMore': False, 'items': [3], 'lastTimestamp': 1400000000003}
+
+        self.client.send_signed_request = Mock(side_effect=[first_response, second_response, third_response])
+
+        expected_query_parameters = ['', 'since=1400000000001', '']
+
+        index = 0
+        for response in [self.client.item_iterator('/some/url'), self.client.item_iterator('/some/url')]:
+            for _ in response:
+                self.assertEqual(expected_query_parameters[index], self.client.get_query_parameters())
+                index+=1
+
+        self.assertEqual(self.client.send_signed_request.call_count, 3)
+
     def test_get_resource(self):
         self.client.item_iterator = Mock()
         self.client.send_signed_request = Mock()

usabilla.py

@@ -311,6 +311,8 @@ def item_iterator(self, url):
                 yield item
             self.set_query_parameters({'since': results['lastTimestamp']})
 
+        self.set_query_parameters({})
+
     def get_resource(self, scope, product, resource, resource_id=None, iterate=False):
         """Retrieves resources of the specified type