make test.py more reselient to flakyness in xvfb-run + DumpRenderTree

tools/testing/test_case.py

 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 """Common TestCase subclasses used to define a single test."""
 
 import os
 import tempfile
 
 import test
@@ skipping 106 matching lines @@
       # If errors were found, fail fast and show compile errors:
       if test_output.output.exit_code != 0:
         return test_output
 
     command = self.run_arch.GetRunCommand()
     test_output = self.RunCommand(command)
     # The return value of DumpRenderedTree does not indicate test failing, but
     # the output does.
     if self.run_arch.HasFailed(test_output.output.stdout):
       test_output.output.exit_code = 1
+      # DumpRenderTree is sometimes flaky in xvfb-run, try again in that case.
+      if (self.run_arch.WasFlakyDrt(test_output.output.stderr)):
+        print "\nFlaky Gtw-WARNING error found, trying again..."
+        test_output = self.RunCommand(command)
+        if self.run_arch.HasFailed(test_output.output.stdout):
+          test_output.output.exit_code = 1
 
     return test_output
 
 
 class CompilationTestCase(test.TestCase):
   """Run the dartc compiler on a given top level .dart file."""
 
   def __init__(self, path, context, filename, mode, arch, component):
     super(CompilationTestCase, self).__init__(context, path)
     self.filename = filename
@@ skipping 24 matching lines @@
             self.filename]
 
     return cmd
 
   def GetName(self):
     return self.path[-1]
 
   def Cleanup(self):
     if not self.context.keep_temporary_files:
       self.run_arch.Cleanup()