Add an option to specify pylint version

This allows us to migrate PRESUBMIT.py files over to pylint-2.6 bit by
bit. It also allows us to support and upgrade pylint to newer versions
in the future.

Bug: 1221143
Fixed: 1221143
Change-Id: I9af96f5f06caf48e9923ad5fae75b98a0a7aeb49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2994723
Commit-Queue: Peter Wen <wnwen@chromium.org>
Auto-Submit: Peter Wen <wnwen@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>

presubmit_canned_checks.py

@@ -909,16 +909,21 @@ def GetPylint(input_api,
               files_to_skip=None,
               disabled_warnings=None,
               extra_paths_list=None,
-              pylintrc=None):
+              pylintrc=None,
+              version='1.5'):
   """Run pylint on python files.
 
   The default files_to_check enforces looking only at *.py files.
+
+  Currently only pylint version '1.5' and '2.6' are supported.
   """
 
   files_to_check = tuple(files_to_check or (r'.*\.py$', ))
   files_to_skip = tuple(files_to_skip or input_api.DEFAULT_FILES_TO_SKIP)
   extra_paths_list = extra_paths_list or []
 
+  assert version in ('1.5', '2.6'), 'Unsupported pylint version: ' + version
+
   if input_api.is_committing:
     error_type = output_api.PresubmitError
   else:
@@ -969,7 +974,7 @@ def GetPylint(input_api,
     # Windows needs help running python files so we explicitly specify
     # the interpreter to use. It also has limitations on the size of
     # the command-line, so we pass arguments via a pipe.
-    tool = input_api.os_path.join(_HERE, 'pylint')
+    tool = input_api.os_path.join(_HERE, 'pylint-' + version)
     kwargs = {'env': env}
     if input_api.platform == 'win32':
       # On Windows, scripts on the current directory take precedence over PATH.

pylint-1.5.bat

@@ -0,0 +1,12 @@
+@echo off
+:: Copyright 2021 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.
+setlocal
+
+:: Ensure that "depot_tools" is somewhere in PATH so this tool can be used
+:: standalone, but allow other PATH manipulations to take priority.
+set PATH=%PATH%;%~dp0
+
+:: Defer control.
+vpython "%~dp0\pylint-1.5" %*

tests/presubmit_unittest.py

@@ -2519,7 +2519,7 @@ the current line as well!
     subprocess.Popen.return_value = process
     presubmit.sigint_handler.wait.return_value = ('', None)
 
-    pylint = os.path.join(_ROOT, 'pylint')
+    pylint = os.path.join(_ROOT, 'pylint-1.5')
     pylintrc = os.path.join(_ROOT, 'pylintrc')
     env = {str('PYTHONPATH'): str('')}
     if sys.platform == 'win32':