Add new presubmit check RunPythonUnitTests.

tests/presubmit_unittest.py

 #!/usr/bin/python
 # Copyright (c) 2006-2009 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.py and presubmit_canned_checks.py."""
 
 import os
 import StringIO
 import sys
@@ skipping 574 matching lines @@
     def RightHandSideLines(self):
       for line in self.lines:
         yield (presubmit.AffectedFile('bingo', 'M'), 1, line)
 
   def testMembersChanged(self):
     members = [
       'CheckChangeHasBugField', 'CheckChangeHasNoTabs',
       'CheckChangeHasQaField', 'CheckChangeHasTestedField',
       'CheckChangeHasTestField', 'CheckDoNotSubmit',
       'CheckDoNotSubmitInDescription', 'CheckDoNotSubmitInFiles',
-      'CheckLongLines', 'CheckTreeIsOpen',
+      'CheckLongLines', 'CheckTreeIsOpen', 'RunPythonUnitTests',
     ]
     # If this test fails, you should add the relevant test.
     self.compareMembers(presubmit_canned_checks, members)
 
   def testCannedCheckChangeHasBugField(self):
     change = self.MakeBasicChange('foo',
                                   'Foo\nBUG=1234')
     api = presubmit.InputApi(change, './PRESUBMIT.py')
     self.failIf(presubmit_canned_checks.CheckChangeHasBugField(
         api, presubmit.OutputApi))
@@ skipping 80 matching lines @@
     ))
 
   def testCannedCheckTreeIsOpen(self):
     self.failIf(presubmit_canned_checks.CheckTreeIsOpen(
       self.MockInputApi(), presubmit.OutputApi, url='url_to_open', closed='0'
     ))
     self.failUnless(presubmit_canned_checks.CheckTreeIsOpen(
       self.MockInputApi(), presubmit.OutputApi, url='url_to_closed', closed='0'
     ))
 
+  def RunPythonUnitTests(self):
+    # TODO(maruel): Add real tests.
+    self.failIf(presubmit_canned_checks.RunPythonUnitTests(
+        self.MockInputApi(),
+        presubmit.OutputApi, []))
+    self.failUnless(presubmit_canned_checks.RunPythonUnitTests(
+        self.MockInputApi(),
+        presubmit.OutputApi, ['non_existent_module']))
 
 if __name__ == '__main__':
   unittest.main()