Add hacking check to ensure not use xrange()

xrange() does not exist in python3.
Add hacking check rule so that codes with xragne() never pass test.

Change-Id: I40f6d9aab3ef334da46bd460eb6a4ed3948e951e

HACKING.rst

@@ -24,3 +24,4 @@ glance Specific Commandments
 - [G326] Validate that LOG.warning messages use _LW.
 - [G327] Prevent use of deprecated contextlib.nested
 - [G328] Must use a dict comprehension instead of a dict constructor with a sequence of key-value pairs
+- [G329] Python 3: Do not use xrange.

glance/hacking/checks.py

@@ -156,6 +156,12 @@ def dict_constructor_with_list_copy(logical_line):
         yield (0, msg)
 
 
+def check_python3_xrange(logical_line):
+    if re.search(r"\bxrange\s*\(", logical_line):
+        yield(0, "G329: Do not use xrange. Use range, or six.moves.range for "
+                 "large loops.")
+
+
 def factory(register):
     register(assert_true_instance)
     register(assert_equal_type)
@@ -165,3 +171,4 @@ def factory(register):
     register(validate_log_translations)
     register(check_no_contextlib_nested)
     register(dict_constructor_with_list_copy)
+    register(check_python3_xrange)

glance/tests/test_hacking.py

@@ -100,3 +100,11 @@ class HackingTestCase(utils.BaseTestCase):
 
         self.assertEqual(0, len(list(checks.dict_constructor_with_list_copy(
             "      self._render_dict(xml, data_el, data.__dict__)"))))
+
+    def test_check_python3_xrange(self):
+        func = checks.check_python3_xrange
+        self.assertEqual(1, len(list(func('for i in xrange(10)'))))
+        self.assertEqual(1, len(list(func('for i in xrange    (10)'))))
+        self.assertEqual(0, len(list(func('for i in range(10)'))))
+        self.assertEqual(0, len(list(func('for i in six.moves.range(10)'))))
+        self.assertEqual(0, len(list(func('testxrange(10)'))))