Pass arguments to pylint child process via a pipe.

tests/presubmit_unittest.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Unit tests for presubmit_support.py and presubmit_canned_checks.py."""
 
 # pylint: disable=E1101,E1103
 
 import logging
 import os
 import StringIO
+import subprocess
 import sys
 import time
 
 _ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 sys.path.insert(0, _ROOT)
 
 from testing_support.super_mox import mox, SuperMoxTestBase
 
 import owners
 import presubmit_support as presubmit
@@ skipping 2113 matching lines @@
   def testCannedRunPylint(self):
     input_api = self.MockInputApi(None, True)
     input_api.environ = self.mox.CreateMock(os.environ)
     input_api.environ.copy().AndReturn({})
     input_api.AffectedSourceFiles(mox.IgnoreArg()).AndReturn(True)
     input_api.PresubmitLocalPath().AndReturn('/foo')
     input_api.PresubmitLocalPath().AndReturn('/foo')
     input_api.os_walk('/foo').AndReturn([('/foo', [], ['file1.py'])])
     pylint = os.path.join(_ROOT, 'third_party', 'pylint.py')
     pylintrc = os.path.join(_ROOT, 'pylintrc')
-    input_api.subprocess.call(
-        ['pyyyyython', pylint, 'file1.py', '--rcfile=%s' % pylintrc],
-        env=mox.IgnoreArg())
+
+    # Create a mock Popen object, and set up its expectations.
+    child = self.mox.CreateMock(subprocess.Popen)
+    child.stdin = self.mox.CreateMock(file)
+    child.stdin.write('file1.py\n')
+    child.stdin.write('--rcfile=%s\n' % pylintrc)
+    child.stdin.close()
+    child.communicate()
+    child.returncode = 0
+
+    input_api.subprocess.Popen(['pyyyyython', pylint, '--args-on-stdin'],
+        env=mox.IgnoreArg(), stdin=subprocess.PIPE).AndReturn(child)
     self.mox.ReplayAll()
 
     results = presubmit_canned_checks.RunPylint(
         input_api, presubmit.OutputApi)
     self.assertEquals([], results)
 
   def testCheckBuildbotPendingBuildsBad(self):
     input_api = self.MockInputApi(None, True)
     connection = self.mox.CreateMockAnything()
     input_api.urllib2.urlopen('uurl').AndReturn(connection)
@@ skipping 299 matching lines @@
         owners_check=False)
     self.assertEqual(1, len(results))
     self.assertEqual(
         'Found line ending with white spaces in:', results[0]._message)
     self.checkstdout('')
 
 
 if __name__ == '__main__':
   import unittest
   unittest.main()