Implement a proxy checker class.

Add a proxy checker class for local checks that doesn't do anything,
but instead registers a command option that allows for local, in-tree
checks.

Change-Id: I3f7567639ae47cc422c84f319f1b607ad193d901
Reviewed-on: https://review.openstack.org/28220
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Giampaolo Lauria <lauria@us.ibm.com>
Reviewed-by: Sean Dague <sean@dague.net>
Approved: Joe Gordon <jogo@cloudscaling.com>
Reviewed-by: Joe Gordon <jogo@cloudscaling.com>
Tested-by: Jenkins

README.rst

@@ -301,3 +301,24 @@ and how to split up commits into a series of changes, consult the
 project wiki:
 
    http://wiki.openstack.org/GitCommitMessages
+
+Local Checks
+============
+
+hacking supports having local changes in a source tree. They can be configured
+to run in two different ways. They can be registered individually, or with
+a factory function.
+
+For individual registration, put a comma separated list of pep8 compatible
+check functions into the hacking section of tox.ini. Like
+
+  [hacking]
+  local-check = nova.tests.hacking.bad_code_is_terrible
+
+Alternately, you can specify the location of a callable that will be called
+at registration time and will be passed the registration function. The callable
+should expect to call the passed in function on everything if wants to
+register. Such as:
+
+  [hacking]
+  local-check-factory = nova.tests.hacking.factory

hacking/core.py

@@ -21,6 +21,7 @@
 Built as a sets of pep8 checks using flake8.
 """
 
+import ConfigParser
 import gettext
 import imp
 import logging
@@ -31,6 +32,9 @@ import sys
 import tokenize
 import traceback
 
+import d2to1.util
+import pep8
+
 # Don't need this for testing
 logging.disable('LOG')
 
@@ -560,6 +564,9 @@ class GlobalCheck(object):
                 for r in ret:
                     yield ret
 
+    def run_once(self):
+        pass
+
 
 class GitCheck(GlobalCheck):
 
@@ -634,3 +641,37 @@ class OnceGitCheckCommitTitleLength(GitCheck):
                 "H802: git commit title ('%s') should be under 50 chars"
                 % title.strip(),
                 self.name)
+
+
+class ProxyChecks(GlobalCheck):
+    """Provide a mechanism for locally defined checks."""
+
+    name = 'ProxyChecker'
+
+    def __init__(self, tree, *args):
+        pass
+
+    @classmethod
+    def add_options(cls, parser):
+        # Abusing this method because of when it gets called
+        if not os.path.exists('tox.ini'):
+            return
+        tox_ini = ConfigParser.RawConfigParser()
+        tox_ini.read('tox.ini')
+        if not tox_ini.has_section('hacking'):
+            return
+
+        # We're looking for local checks, so we need to include the local
+        # dir in the search path
+        sys.path.append('.')
+        if tox_ini.has_option('hacking', 'local-check'):
+            for check_path in set(
+                    tox_ini.get('hacking', 'local-check').split(",")):
+                if check_path.strip():
+                    checker = d2to1.util.resolve_name(check_path)
+                    pep8.register_check(checker)
+        if tox_ini.has_option('hacking', 'local-check-factory'):
+            factory = d2to1.util.resolve_name(
+                tox_ini.get('hacking', 'local-check-factory'))
+            factory(pep8.register_check)
+        sys.path.pop()

setup.cfg

@@ -26,6 +26,7 @@ setup-hooks =
 
 [entry_points]
 flake8.extension = 
+	H000 = hacking.core:ProxyChecks
 	H101 = hacking.core:hacking_todo_format
 	H201 = hacking.core:hacking_except_format
 	H202 = hacking.core:hacking_except_format_assert