Add a hacking rule for consistent HTTP501 message

There is raise_feature_not_supported() for returning a HTTP501
response with consistent error message, and this patch adds a rule
for enforcing to use the method on v2.1 API.

Partially implements blueprint v2-on-v3-api

Change-Id: I06f254fd9c8d8b6aac4ed135c6c407f3a993431f

HACKING.rst

@@ -50,6 +50,7 @@ Nova Specific Commandments
 - [N338] Change assertEqual(A in B, True), assertEqual(True, A in B),
   assertEqual(A in B, False) or assertEqual(False, A in B) to the more specific
   assertIn/NotIn(A, B)
+- [N339] Check common raise_feature_not_supported() is used for v2.1 HTTPNotImplemented response.
 
 Creating Unit Tests
 -------------------

nova/hacking/checks.py

@@ -95,6 +95,7 @@ custom_underscore_check = re.compile(r"(.)*_\s*=\s*(.)*")
 api_version_re = re.compile(r"@.*api_version")
 dict_constructor_with_list_copy_re = re.compile(r".*\bdict\((\[)?(\(|\[)")
 decorator_re = re.compile(r"@.*")
+http_not_implemented_re = re.compile(r"raise .*HTTPNotImplemented\(")
 
 # TODO(dims): When other oslo libraries switch over non-namespace'd
 # imports, we need to add them to the regexp below.
@@ -539,6 +540,17 @@ def assert_equal_in(logical_line):
                   "contents.")
 
 
+def check_http_not_implemented(logical_line, physical_line, filename):
+    msg = ("N339: HTTPNotImplemented response must be implemented with"
+           " common raise_feature_not_supported().")
+    if pep8.noqa(physical_line):
+        return
+    if "nova/api/openstack/compute/plugins/v3" not in filename:
+        return
+    if re.match(http_not_implemented_re, logical_line):
+        yield(0, msg)
+
+
 def factory(register):
     register(import_no_db_in_virt)
     register(no_db_session_in_public_api)
@@ -565,3 +577,4 @@ def factory(register):
     register(assert_true_or_false_with_in)
     register(dict_constructor_with_list_copy)
     register(assert_equal_in)
+    register(check_http_not_implemented)

nova/tests/unit/test_hacking.py

@@ -533,3 +533,25 @@ class HackingTestCase(test.NoDBTestCase):
 
         self.assertEqual(0, len(list(checks.dict_constructor_with_list_copy(
             "      self._render_dict(xml, data_el, data.__dict__)"))))
+
+    def test_check_http_not_implemented(self):
+        code = """
+               except NotImplementedError:
+                   common.raise_http_not_implemented_error()
+               """
+        filename = "nova/api/openstack/compute/plugins/v3/test.py"
+        self._assert_has_no_errors(code, checks.check_http_not_implemented,
+                                   filename=filename)
+
+        code = """
+               except NotImplementedError:
+                   msg = _("Unable to set password on instance")
+                   raise exc.HTTPNotImplemented(explanation=msg)
+               """
+        errors = [(3, 4, 'N339')]
+        self._assert_has_errors(code, checks.check_http_not_implemented,
+                                expected_errors=errors, filename=filename)
+
+        filename = "nova/api/openstack/compute/contrib/test.py"
+        self._assert_has_no_errors(code, checks.check_http_not_implemented,
+                                   filename=filename)