Merge "use function next() instead of next() method on iterator objects"

tests/hacking/README.rst

@@ -29,4 +29,5 @@ Rally Specific Commandments
  * [N334] - Ensure that ``itertools.imap`` is not used
  * [N335] - Ensure that ``xrange`` is not used
  * [N336] - Ensure that ``string.lowercase`` and ``string.uppercase`` are not used
+ * [N337] - Ensure that ``next()`` method on iterator objects is not used
 * [N340] - Ensure that we are importing always ``from rally import objects``

tests/hacking/checks.py

@@ -53,6 +53,7 @@ re_itertools_imap_method = re.compile(r"(^|[\s=])itertools\.imap\(")
 re_xrange_method = re.compile(r"(^|[\s=])xrange\(")
 re_string_lower_upper_case_method = re.compile(
     r"(^|[(,\s=])string\.(lower|upper)case([)\[,\s]|$)")
+re_next_on_iterator_method = re.compile(r"\.next\(\)")
 
 
 def _parse_assert_mock_str(line):
@@ -322,6 +323,21 @@ def check_string_lower_upper_case_method(logical_line):
                   "rather than string.lowercase or string.uppercase.")
 
 
+def check_next_on_iterator_method(logical_line):
+    """Check if next() method on iterator objects are properly called
+
+    Python 3 introduced a next() function to replace the next() method on
+    iterator objects. Rather than calling the method on the iterator,
+    the next() function is called with the iterable object as it's sole
+    parameter, which calls the underlying __next__() method.
+
+    N337
+    """
+    res = re_next_on_iterator_method.search(logical_line)
+    if res:
+        yield (0, "N337: Use next(iterator) rather than iterator.next().")
+
+
 def check_no_direct_rally_objects_import(logical_line, filename):
     """Check if rally.objects are properly imported.
 
@@ -356,4 +372,5 @@ def factory(register):
     register(check_itertools_imap_method)
     register(check_xrange_method)
     register(check_string_lower_upper_case_method)
+    register(check_next_on_iterator_method)
     register(check_no_direct_rally_objects_import)

tests/unit/test_hacking.py

@@ -176,6 +176,13 @@ class HackingTestCase(test.TestCase):
         self.assertEqual(len(list(checks.check_string_lower_upper_case_method(
             "string.ascii_uppercase[:16]"))), 0)
 
+    def test_check_next_on_iterator_method(self):
+        self.assertEqual(len(list(checks.check_next_on_iterator_method(
+            "iterator.next()"))), 1)
+
+        self.assertEqual(len(list(checks.check_next_on_iterator_method(
+            "next(iterator)"))), 0)
+
     def test_assert_equal_none(self):
         self.assertEqual(len(list(checks.assert_equal_none(
             "self.assertEqual(A, None)"))), 1)