Add hacking rule framework for magnum

This patch adds hacking rule check framework for magnum, and adds first rule:
policy.enforce_wsgi decorator must be the first decorator on a method.

refer this link for why we need this rule.
`https://review.openstack.org/#/c/190140/`

Closes-Bugs: #1465895
Change-Id: If98e47426b391b75755ca0b559aee1baa93b8503

HACKING.rst

@@ -1,4 +1,11 @@
 magnum Style Commandments
 =========================
 
-Read the OpenStack Style Commandments http://docs.openstack.org/developer/hacking/
+- Step 1: Read the OpenStack Style Commandments
+  http://docs.openstack.org/developer/hacking/
+- Step 2: Read on
+
+magnum Specific Commandments
+---------------------------
+
+- [N301] policy.enforce_wsgi decorator must be the first decorator on a method.

magnum/hacking/checks.py

@@ -0,0 +1,47 @@
+# Copyright (c) 2015 Intel, Inc.
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import re
+
+"""
+Guidelines for writing new hacking checks
+
+ - Use only for Magnum specific tests. OpenStack general tests
+   should be submitted to the common 'hacking' module.
+ - Pick numbers in the range N3xx. Find the current test with
+   the highest allocated number and then pick the next value.
+ - Keep the test method code in the source file ordered based
+   on the N3xx value.
+ - List the new rule in the top level HACKING.rst file
+ - Add test cases for each new rule to magnum/tests/unit/test_hacking.py
+
+"""
+
+enforce_re = re.compile(r"@policy.enforce_wsgi*")
+decorator_re = re.compile(r"@.*")
+
+
+def check_policy_enforce_decorator(logical_line,
+                                   previous_logical, blank_before,
+                                   filename):
+    msg = ("N301: the policy.enforce_wsgi decorator must be the "
+           "first decorator on a method.")
+    if (blank_before == 0 and re.match(enforce_re, logical_line)
+            and re.match(decorator_re, previous_logical)):
+        yield(0, msg)
+
+
+def factory(register):
+    register(check_policy_enforce_decorator)

magnum/tests/unit/test_hacking.py

@@ -0,0 +1,85 @@
+#    Copyright 2915 Intel, Inc.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import mock
+import pep8
+import textwrap
+
+from magnum.hacking import checks
+from magnum.tests import base
+
+
+class HackingTestCase(base.TestCase):
+    """This class tests the hacking checks in magnum.hacking.checks by passing
+    strings to the check methods like the pep8/flake8 parser would. The parser
+    loops over each line in the file and then passes the parameters to the
+    check method. The parameter names in the check method dictate what type of
+    object is passed to the check method. The parameter types are::
+
+        logical_line: A processed line with the following modifications:
+            - Multi-line statements converted to a single line.
+            - Stripped left and right.
+            - Contents of strings replaced with "xxx" of same length.
+            - Comments removed.
+        physical_line: Raw line of text from the input file.
+        lines: a list of the raw lines from the input file
+        tokens: the tokens that contribute to this logical line
+        line_number: line number in the input file
+        total_lines: number of lines in the input file
+        blank_lines: blank lines before this one
+        indent_char: indentation character in this file (" " or "\t")
+        indent_level: indentation (with tabs expanded to multiples of 8)
+        previous_indent_level: indentation on previous line
+        previous_logical: previous logical line
+        filename: Path of the file being run through pep8
+
+    When running a test on a check method the return will be False/None if
+    there is no violation in the sample input. If there is an error a tuple is
+    returned with a position in the line, and a message. So to check the result
+    just assertTrue if the check is expected to fail and assertFalse if it
+    should pass.
+    """
+    # We are patching pep8 so that only the check under test is actually
+    # installed.
+
+    @mock.patch('pep8._checks',
+                {'physical_line': {}, 'logical_line': {}, 'tree': {}})
+    def _run_check(self, code, checker, filename=None):
+        pep8.register_check(checker)
+
+        lines = textwrap.dedent(code).strip().splitlines(True)
+
+        checker = pep8.Checker(filename=filename, lines=lines)
+        checker.check_all()
+        checker.report._deferred_print.sort()
+        return checker.report._deferred_print
+
+    def _assert_has_errors(self, code, checker, expected_errors=None,
+                           filename=None):
+        actual_errors = [e[:3] for e in
+                         self._run_check(code, checker, filename)]
+        self.assertEqual(expected_errors or [], actual_errors)
+
+    def _assert_has_no_errors(self, code, checker, filename=None):
+        self._assert_has_errors(code, checker, filename=filename)
+
+    def test_policy_enforce_decorator(self):
+        code = """
+               @some_other_decorator
+               @policy.enforce_wsgi("bay", "create")
+               def my_method():
+                   pass
+               """
+        self._assert_has_errors(code, checks.check_policy_enforce_decorator,
+                                expected_errors=[(2, 0, "N301")])

tox.ini

@@ -56,6 +56,9 @@ commands =
 ignore = E131,E251,H302,H405,H803,H904,E711
 exclude =  .venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,tools,magnum/common/pythonk8sclient
 
+[hacking]
+local-check-factory = magnum.hacking.checks.factory
+
 [testenv:pip-missing-reqs]
 # do not install test-requirements as that will pollute the virtualenv for
 # determining missing packages