Make sure images are loaded before running tests

run_jstests.py

 #!/usr/bin/env python
 # 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.
 
 """Runs DomDistillers jstests.
 
 This uses ChromeDriver (https://sites.google.com/a/chromium.org/chromedriver/) to run the jstests.
 This requires that the ChromeDriver executable is on the PATH and that Selenium WebDriver is
 installed.
@@ skipping 31 matching lines @@
 
   if options.debug_level:
     params['debug_level'] = int(options.debug_level)
 
   if options.no_console_log:
     params['console_log'] = '0'
 
   if options.shuffle:
     params['shuffle'] = options.shuffle
 
-  test_runner = "return org.chromium.distiller.JsTestEntry.run()";
+  image_loaded = "return window.image_loaded"
+  test_runner = "return org.chromium.distiller.JsTestEntry.run()"
   test_html = os.path.abspath(os.path.join(os.path.dirname(__file__), "war", "test.html"))
   test_html += "?" + urllib.urlencode(params)
 
   chrome_options = webdriver.ChromeOptions()
 
   # Travis-CI uses OpenVZ containers which are incompatible with the sandbox technology.
   # See https://code.google.com/p/chromium/issues/detail?id=31077 for more information.
   # Ref: https://github.com/travis-ci/travis-ci/issues/938#issuecomment-16336150
   # Drone.io also has issues running newer versions of Chrome.
   # Ref: http://crbug.com/495254
   if options.no_sandbox:
     chrome_options.add_argument("--no-sandbox")
 
   driver = webdriver.Chrome(chrome_options=chrome_options)
-  driver.get("file://" + test_html)
   for i in range(options.repeat):
+    driver.get("file://" + test_html)
+    while not driver.execute_script(image_loaded):

[mdjones, 2017/03/22 17:35:04]

I'd check to see if there is a execute-and-wait version of this so we don't need
the timer.

[wychen, 2017/04/11 00:22:55]

I gave selenium.webdriver.support.expected_conditions a try, but strangely,
waiting for a state specified in the image onload handler doesn't guarantee the
image to be decoded already. The failure rate is about 2/1000. Might be some
strange timing issue, but I haven't figured out why.

Given the failure rate of current impl is <1/1000, I'll just go with this one.

+      print "Wait for image loading..."
+      time.sleep(0.1)
+
     start = time.time()
     result = driver.execute_script(test_runner)
+    end = time.time()
 
-    end = time.time()
     if not result['success'] or options.repeat == i+1:
       print result['log'].encode('utf-8')
     print 'Tests run: %d, Failures: %d, Skipped: %d, Time elapsed: %0.3f sec' % (result['numTests'],
         result['failed'], result['skipped'], end - start)
     if not result['success']:
       driver.quit()
       if options.repeat > 1:
         print 'Failed at run #%d/%d' % (i+1, options.repeat)
       return 1
   driver.quit()
   if options.repeat > 1:
     print 'Passed %d runs' % (options.repeat)
   return 0
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))