Add hacking check to ensure not use xrange()

Added hacking check to ensure not to use xrange.

Change-Id: I28731e16cf0636f004bf96795c85eecbdf2f8fbd
Closes-Bug: #1538118

HACKING.rst

@@ -22,3 +22,4 @@ Magnum Specific Commandments
 - [M336] Must use a dict comprehension instead of a dict constructor
   with a sequence of key-value pairs.
 - [M338] Use assertIn/NotIn(A, B) rather than assertEqual(A in B, True/False).
+- [M339] Don't use xrange()

magnum/hacking/checks.py

@@ -49,6 +49,8 @@ assert_true_isinstance_re = re.compile(
     r"(.)*assertTrue\(isinstance\((\w|\.|\'|\"|\[|\])+, "
     "(\w|\.|\'|\"|\[|\])+\)\)")
 dict_constructor_with_list_copy_re = re.compile(r".*\bdict\((\[)?(\(|\[)")
+assert_xrange_re = re.compile(
+    r"\s*xrange\s*\(")
 
 
 def assert_equal_none(logical_line):
@@ -112,6 +114,15 @@ def assert_equal_in(logical_line):
                   "contents.")
 
 
+def no_xrange(logical_line):
+    """Disallow 'xrange()'
+
+    M339
+    """
+    if assert_xrange_re.match(logical_line):
+        yield(0, "M339: Do not use xrange().")
+
+
 def use_timeutils_utcnow(logical_line, filename):
     # tools are OK to use the standard datetime module
     if "/tools/" in filename:
@@ -142,3 +153,4 @@ def factory(register):
     register(assert_equal_in)
     register(use_timeutils_utcnow)
     register(dict_constructor_with_list_copy)
+    register(no_xrange)

magnum/tests/unit/test_hacking.py

@@ -179,6 +179,16 @@ class HackingTestCase(base.TestCase):
         code = "self.assertTrue()"
         self._assert_has_no_errors(code, check)
 
+    def test_no_xrange(self):
+        errors = [(1, 0, "M339")]
+        check = checks.no_xrange
+
+        code = "xrange(45)"
+        self._assert_has_errors(code, check, errors)
+
+        code = "range(45)"
+        self._assert_has_no_errors(code, check)
+
     def test_use_timeunitls_utcow(self):
         errors = [(1, 0, "M310")]
         check = checks.use_timeutils_utcnow