Enhance RunPylint to use white_list and black_list arguments.

presubmit_canned_checks.py

 # Copyright (c) 2010 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generic presubmit checks that can be reused by other presubmit checks."""
 
 ### Description checks
 
 def CheckChangeHasTestField(input_api, output_api):
   """Requires that the changelist have a TEST= field."""
@@ skipping 432 matching lines @@
     # Discard the output if returncode == 0
     if subproc.returncode:
       outputs.append('Test \'%s\' failed with code %d\n%s\n%s\n' % (
           unit_test_name, subproc.returncode, stdoutdata, stderrdata))
   if outputs:
     return [message_type('%d unit tests failed.' % len(outputs),
                                 long_text='\n'.join(outputs))]
   return []
 
 
-def RunPylint(input_api, output_api, source_file_filter=None):
-  """Run pylint on python files."""
-  import warnings
+def RunPylint(input_api, output_api, white_list=None, black_list=None):
+  """Run pylint on python files.
+
+  The default white_list enforces looking only a *.py files.
+  """
+  white_list = white_list or ['.*\.py$']
+  black_list = black_list or input_api.DEFAULT_BLACK_LIST
+
+  # Only trigger if there is at least one python file affected.
+  src_filter = lambda x: input_api.FilterSourceFile(x, white_list, black_list)
+  if not input_api.AffectedSourceFiles(src_filter):
+    return []
+
   # On certain pylint/python version combination, running pylint throws a lot of
   # warning messages.
+  import warnings
   warnings.filterwarnings('ignore', category=DeprecationWarning)
   try:
-    if not source_file_filter:
-      source_file_filter = lambda f: f.LocalPath().endswith('.py')
-    files = [f.LocalPath()
-            for f in input_api.AffectedSourceFiles(source_file_filter)]
+    # We cannot use AffectedFiles here because we want to test every python
+    # file on each single python change. It's because a change in a python file
+    # can break another unmodified file.
+    # Use code similar to InputApi.FilterSourceFile()
+    def Find(filepath, filters):
+      for item in filters:
+        if input_api.re.match(item, filepath):
+          return True
+      return False
+
+    import os
+    files = []
+    for dirpath, dirnames, filenames in os.walk(input_api.PresubmitLocalPath()):
+      # Passes dirnames in black list to speed up search.
+      for item in dirnames[:]:
+        if Find(input_api.os_path.join(dirpath, item), black_list):
+          dirnames.remove(item)
+      for item in filenames:
+        filepath = input_api.os_path.join(dirpath, item)
+        if Find(filepath, white_list) and not Find(filepath, black_list):
+          files.append(filepath)
+
+    # Now that at least one python file was modified and all the python files
+    # were listed, try to run pylint.
     try:
       from pylint import lint
       if lint.Run(sorted(files)):
         return [output_api.PresubmitPromptWarning('Fix pylint errors first.')]
       return []
     except ImportError:
       if input_api.platform == 'win32':
         return [output_api.PresubmitNotifyResult(
           'Warning: Can\'t run pylint because it is not installed. Please '
           'install manually\n'
@@ skipping 82 matching lines @@
     pending_builds_len = len(builder.get('pending_builds', []))
     if pending_builds_len > max_pendings:
       out.append('%s has %d build(s) pending' %
                   (builder_name, pending_builds_len))
   if out:
     return [output_api.PresubmitPromptWarning(
         'Build(s) pending. It is suggested to wait that no more than %d '
             'builds are pending.' % max_pendings,
         long_text='\n'.join(out))]
   return []