Merge pull request #16523 from bobsilverberg/stop_exception

Bug 972557 - To address Bug 971747 - Add an exception that will report when b2g cannot be stopped

tests/python/gaia-ui-tests/gaiatest/gaia_test.py

@@ -723,12 +723,19 @@ def start_b2g(self, timeout=60):
         self.marionette.import_script(self.lockscreen_atom)
         self.update_checker.check_updates()
 
-    def stop_b2g(self):
+    @property
+    def is_b2g_running(self):
+        return 'b2g' in self.manager.shellCheckOutput(['toolbox', 'ps'])
+
+    def stop_b2g(self, timeout=5):
         if self.marionette.instance:
             # close the gecko instance attached to marionette
             self.marionette.instance.close()
         elif self.is_android_build:
             self.manager.shellCheckOutput(['stop', 'b2g'])
+            Wait(self.marionette, timeout=timeout).until(
+                lambda m: not self.is_b2g_running,
+                message='b2g failed to stop.')
         else:
             raise Exception('Unable to stop B2G')
         self.marionette.client.close()