[test-runner] Move test case processing beyond the multi-process boundary.

test/cctest/testcfg.py

 # Copyright 2008 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 26 matching lines @@
 class CcTestSuite(testsuite.TestSuite):
 
   def __init__(self, name, root):
     super(CcTestSuite, self).__init__(name, root)
     if utils.IsWindows():
       build_dir = "build"
     else:
       build_dir = "out"
     self.serdes_dir = os.path.normpath(
         os.path.join(root, "..", "..", build_dir, ".serdes"))
+
+  def SetupWorkingDirectory(self):
+    # This is only called once per machine, while init above is called once per
+    # process.
     if os.path.exists(self.serdes_dir):
       shutil.rmtree(self.serdes_dir, True)
     os.makedirs(self.serdes_dir)
 
   def ListTests(self, context):
     shell = os.path.abspath(os.path.join(context.shell_dir, self.shell()))
     if utils.IsWindows():
       shell += ".exe"
     output = commands.Execute(context.command_prefix +
                               [shell, "--list"] +
@@ skipping 24 matching lines @@
     serialization_file += ''.join(testcase.flags).replace('-', '_')
     return (testcase.flags + [testcase.path] + context.mode_flags +
             ["--testing_serialization_file=" + serialization_file])
 
   def shell(self):
     return "cctest"
 
 
 def GetSuite(name, root):
   return CcTestSuite(name, root)