Add more diagnostic tracing when a JSON call doesn't return.

chrome/test/pyautolib/pyauto.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """PyAuto: Python Interface to Chromium's Automation Proxy.
 
 PyAuto uses swig to expose Automation Proxy interfaces to Python.
 For complete documentation on the functionality available,
 run pydoc on this file.
@@ skipping 917 matching lines @@
       """
       self._ui_test = ui_test
       self.view = view
       self.frame_xpath = frame_xpath
 
     def Execute(self, script):
       """Execute script in the render view."""
       return self._ui_test.ExecuteJavascriptInRenderView(script,
                                                          self.view,
                                                          self.frame_xpath)
+  def _GetResultFromJSONRequestDiagnostics(self):

[Nirnimesh, 2012/04/13 18:28:04]

nit: need a blank line before this

+    """Same as _GetResultFromJSONRequest without throwing a timeout exception.
+
+    This method is used to diagnose if a command returns without causing a
+    timout exception to be thrown.  This should be used for debugging purposes
+    only.
+
+    Returns:
+      True if the request returned; False if it timed out.
+    """
+    result = self._SendJSONRequest(-1,
+             json.dumps({'command': 'GetBrowserInfo',}),
+             self.action_max_timeout_ms())
+    if not result:
+      # The diagnostic command did not complete, Chrome is probably in a bad
+      # state
+      return False
+    return True
 
   def _GetResultFromJSONRequest(self, cmd_dict, windex=0, timeout=-1):
     """Issue call over the JSON automation channel and fetch output.
 
     This method packages the given dictionary into a json string, sends it
     over the JSON automation channel, loads the json output string returned,
     and returns it back as a dictionary.
 
     Args:
       cmd_dict: the command dictionary. It must have a 'command' key
@@ skipping 16 matching lines @@
     """
     if timeout == -1:  # Default
       timeout = self.action_max_timeout_ms()
     if windex is None:  # Do not target any window
       windex = -1
     result = self._SendJSONRequest(windex, json.dumps(cmd_dict), timeout)
     if not result:
       additional_info = 'No information available.'
       # Windows does not support os.kill until Python 2.7.
       if not self.IsWin() and _BROWSER_PID:
-        additional_info = ('The browser process ID %d still exists. '
-                           'It is possible that it is hung.' % _BROWSER_PID)
+        browser_pid_exists = True
+        # Does the browser PID exist?
         try:
           # Does not actually kill the process
           os.kill(int(_BROWSER_PID), 0)
         except OSError:
-          additional_info = ('The browser process ID %d no longer exists.' %
-                             _BROWSER_PID)
+          browser_pid_exists = False
+        if browser_pid_exists:
+          if self._GetResultFromJSONRequestDiagnostics():
+            # Browser info, worked, that means this hook had a problem
+            additional_info = ('The browser process ID %d still exists. '
+                               'PyAuto was able to get obtain browser info. It '
+                               'is possible this hook is broken.'
+                               % _BROWSER_PID)
+          else:
+            additional_info = ('The browser process ID %d still exists. '
+                               'PyAuto was not able to obtain browser info. '
+                               'It is possible the browser is hung.'
+                               % _BROWSER_PID)
+        else:
+          additional_info = ('The browser process ID %d no longer exists. '
+                             'Perhaps the browser crashed.' % _BROWSER_PID)
       elif not _BROWSER_PID:
         additional_info = ('The browser PID was not obtained. Does this test '
                            'have a unique startup configuration?')
       # Mask private data if it is in the JSON dictionary
       cmd_dict_copy = copy.copy(cmd_dict)
       if 'password' in cmd_dict_copy.keys():
         cmd_dict_copy['password'] = '**********'
       if 'username' in cmd_dict_copy.keys():
         cmd_dict_copy['username'] = 'removed_username'
       raise JSONInterfaceError('Automation call %s received empty response.  '
@@ skipping 4356 matching lines @@
     successful = result.wasSuccessful()
     if not successful:
       pyauto_tests_file = os.path.join(self.TestsDir(), self._tests_filename)
       print >>sys.stderr, 'Tests can be disabled by editing %s. ' \
                           'Ref: %s' % (pyauto_tests_file, _PYAUTO_DOC_URL)
     sys.exit(not successful)
 
 
 if __name__ == '__main__':
   Main()