Add an "in_unit_test_mode" attribute to the environment. Use this to default output format to 'gtes…

content/test/gpu/gpu_tests/screenshot_sync.py

 # Copyright 2014 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.
 import os
 
 import screenshot_sync_expectations as expectations
 
 from telemetry import benchmark
 from telemetry.core import util
 from telemetry.page import page
 from telemetry.page import page_set
 from telemetry.page import page_test
 
 data_path = os.path.join(
     util.GetChromiumSrcDir(), 'content', 'test', 'data', 'gpu')
 
 @benchmark.Disabled('mac')
 class _ScreenshotSyncValidator(page_test.PageTest):
+  options = {'output_format': 'gtest'}
+
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs('--enable-gpu-benchmarking')
 
   def ValidatePage(self, page, tab, results):
     test_success = tab.EvaluateJavaScript('window.__testSuccess')
     if not test_success:
       message = tab.EvaluateJavaScript('window.__testMessage')
       raise page_test.Failure(message)
 
 
@@ skipping 19 matching lines @@
   they were requested"""
   test = _ScreenshotSyncValidator
 
   def CreateExpectations(self, page_set):
     return expectations.ScreenshotSyncExpectations()
 
   def CreatePageSet(self, options):
     ps = page_set.PageSet(file_path=data_path, serving_dirs=[''])
     ps.AddPage(ScreenshotSyncPage(ps, ps.base_dir))
     return ps