Fix selenium to detect and handle browser crashes.

tools/testing/run_selenium.py

 #!/usr/bin/python
 
 # 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.
 #
 
 """Script to actually open a browser and perform the test, and reports back with
 the result. It uses Selenium WebDriver when possible for running the tests. It
 uses Selenium RC for Safari.
@@ skipping 25 matching lines @@
 from selenium.webdriver.support.ui import WebDriverWait
 import shutil
 import signal
 import socket
 import sys
 import time
 import urllib2
 import threading
 
 TIMEOUT_ERROR_MSG = 'FAIL (timeout)'
+CRASH_ERROR_MSG = 'CRASH'
 
 def correctness_test_done(source):
   """Checks if test has completed."""
   return ('PASS' in source) or ('FAIL' in source)
 
 def perf_test_done(source):
   """Tests to see if our performance test is done by printing a score."""
   #This code is written this way to work around a current instability in the
   # python webdriver bindings if you call driver.get_element_by_id.
   #TODO(efortuna): Access these elements in a nicer way using DOM parser.
@@ skipping 21 matching lines @@
   supports Firefox, Chrome, IE, Opera (and some mobile browsers)."""
 
   if isinstance(browser, selenium.selenium):
     return run_test_in_browser_selenium_rc(browser, html_out, timeout, mode,
         refresh)
 
   browser.get(html_out)
   if refresh:
     browser.refresh()
   try:
+    def pythonTimeout():
+      close_browser(browser)
+    # If the browser is crashing selenium may not time out.
+    # Explicitly catch this case with a python timer.
+    t = threading.Timer(timeout, pythonTimeout)
+    t.start()
     test_done = CONFIGURATIONS[mode]
     element = WebDriverWait(browser, float(timeout)).until(
         lambda driver: test_done(driver.page_source))
+    t.cancel()
     return browser.page_source
   except selenium.common.exceptions.TimeoutException:
     return TIMEOUT_ERROR_MSG
+  except:
+    return CRASH_ERROR_MSG
 
 def run_test_in_browser_selenium_rc(sel, html_out, timeout, mode, refresh):
   """ Run the desired test in the browser using Selenium 1.0 syntax, and wait
   for the test to complete. This is used for Safari, since it is not currently
   supported on Selenium 2.0."""
   sel.open(html_out)
   if refresh:
     sel.refresh()
   source = sel.get_html_source()
   end_condition = CONFIGURATIONS[mode]
@@ skipping 116 matching lines @@
   if browser is None:
     return
   if isinstance(browser, selenium.selenium):
     browser.stop()
     return
 
   # A timeout exception is thrown if nothing happens within the time limit.
   if (type(browser) is not selenium.webdriver.chrome.webdriver.WebDriver and
       type(browser) is not selenium.webdriver.ie.webdriver.WebDriver):
     browser.close()
-  browser.quit()
+
+  # The builtin quit call will call close on the RemoteDriver which
+  # may hang. Explicitly call browser.service.stop()
+  if (type(browser) is selenium.webdriver.chrome.webdriver.WebDriver):
+    # We may have called stop before if chrome was hanging.
+    try:
+      browser.service.stop()
+    except:
+      print("Trying to close browser that has already been closed")
+      pass
+  else:
+    browser.quit()
 
 def report_results(mode, source, browser):
   # TODO(vsm): Add a failure check for Dromaeo.
   if mode != 'correctness':
     # We're running a performance test.
     print source.encode('utf8')
     sys.stdout.flush()
     if 'NaN' in source:
       return 1
     else:
@@ skipping 74 matching lines @@
         sys.stderr.write('>>> EOF STDERR\n')
         sys.stderr.flush()
 
         # print one of:
         # >>> TEST {PASS, FAIL, OK, CRASH, FAIL, TIMEOUT}
         status = report_results(mode, source, browser)
         if status == 0:
           print '>>> TEST PASS'
         elif source == TIMEOUT_ERROR_MSG:
           print '>>> TEST TIMEOUT'
+        elif source == CRASH_ERROR_MSG:
+          print '>>> TEST CRASH'
+          # The browser crashed, set the browser to None so that we will
+          # create a new instance on next iteration.
+          browser = None
         else:
           print '>>> TEST FAIL'
         sys.stdout.flush()
     except:
       type, value, traceback = sys.exc_info()
       print "run_selenium.py: Unexpected exception occured: "
       print "    type: ", type
       print "    value: ", value
       print "    traceback: ", traceback
       raise
@@ skipping 31 matching lines @@
   browser = start_browser(browser_name, executable_path, html_out)
 
   try:
     output = run_test_in_browser(browser, html_out, timeout, mode, refresh)
     return report_results(mode, output, browser)
   finally:
     close_browser(browser)
 
 if __name__ == "__main__":
   sys.exit(main(sys.argv))