Add hacking rule for using assertIsNone instead of assertEqual(None,***)

Change-Id: I03d3a45769a1a7a125d9bb1de94d22f9004d8d41
Partial-Bug: #1608173

HACKING.rst

@@ -6,6 +6,8 @@ Read the OpenStack Style Commandments http://docs.openstack.org/developer/hackin
 Murano Specific Commandments
 ---------------------------
 
+- [M318] Change assertEqual(A, None) or assertEqual(None, A) by optimal assert
+  like assertIsNone(A)
 - [M322] Method's default argument shouldn't be mutable.
 - [M323] Python 3: do not use dict.iteritems.
 - [M324] Python 3: do not use dict.iterkeys.

murano/hacking/checks.py

@@ -29,6 +29,23 @@ Guidelines for writing new hacking checks
 """
 
 mutable_default_args = re.compile(r"^\s*def .+\((.+=\{\}|.+=\[\])")
+assert_equal_end_with_none_re = re.compile(
+    r"(.)*assertEqual\((\w|\.|\'|\"|\[|\])+, None\)")
+assert_equal_start_with_none_re = re.compile(
+    r"(.)*assertEqual\(None, (\w|\.|\'|\"|\[|\])+\)")
+
+
+def assert_equal_none(logical_line):
+    """Check for assertEqual(A, None) or assertEqual(None, A) sentences
+
+    M318
+    """
+    msg = ("M318: assertEqual(A, None) or assertEqual(None, A) "
+           "sentences not allowed")
+    res = (assert_equal_start_with_none_re.match(logical_line) or
+           assert_equal_end_with_none_re.match(logical_line))
+    if res:
+        yield (0, msg)
 
 
 def no_mutable_default_args(logical_line):
@@ -63,6 +80,7 @@ def check_no_basestring(logical_line):
 
 
 def factory(register):
+    register(assert_equal_none)
     register(no_mutable_default_args)
     register(check_python3_no_iteritems)
     register(check_python3_no_iterkeys)

murano/tests/unit/test_hacking.py

@@ -74,6 +74,19 @@ class HackingTestCase(base.MuranoTestCase):
     def _assert_has_no_errors(self, code, checker, filename=None):
         self._assert_has_errors(code, checker, filename=filename)
 
+    def test_assert_equal_none(self):
+        errors = [(1, 0, "M318")]
+        check = checks.assert_equal_none
+
+        code = "self.assertEqual(A, None)"
+        self._assert_has_errors(code, check, errors)
+
+        code = "self.assertEqual(None, A)"
+        self._assert_has_errors(code, check, errors)
+
+        code = "self.assertIsNone()"
+        self._assert_has_no_errors(code, check)
+
     def test_no_mutable_default_args(self):
         self.assertEqual(1, len(list(checks.no_mutable_default_args(
             "def get_info_from_bdm(virt_type, bdm, mapping=[])"))))