Check if device disconnects every time the last test of a revision fails

scripts/slave/recipe_modules/auto_bisect/revision_state.py

Index: scripts/slave/recipe_modules/auto_bisect/revision_state.py
diff --git a/scripts/slave/recipe_modules/auto_bisect/revision_state.py b/scripts/slave/recipe_modules/auto_bisect/revision_state.py
index 60610442c1c0412d2d5388c18ee54584c9d62543..2c7b1bd8a5719b0ac5af218d8045e777665205ce 100644
--- a/scripts/slave/recipe_modules/auto_bisect/revision_state.py
+++ b/scripts/slave/recipe_modules/auto_bisect/revision_state.py
@@ -185,7 +185,7 @@ class RevisionState(object):
       return self.bisector.api.m.gitiles.download_file(
           repository_url=url, file_path=file_name, branch=branch)
     except TypeError:
-      print 'Could not read content for %s/%s/%s' % (url, file_name, branch) 
+      print 'Could not read content for %s/%s/%s' % (url, file_name, branch)
       return None
 
   def read_deps(self, recipe_tester_name):
@@ -355,6 +355,14 @@ class RevisionState(object):
         self.bisector.surface_result('MISSING_METRIC')
       return
     self.values += results['values']
+    api = self.bisector.api
+    if test_results['retcodes'][-1] != 0 and (

[sullivan, 2016/08/08 22:13:28]

Is test_results['retcodes'] always defined? Is it always an array with a length?
Roberto, can you help us understand how defensively to program here?

[RobertoCN, 2016/08/08 22:46:42]

it will always be a list. And as long as the test runs once, it will not be
empty. I guess it won't hurt to do:
if test_results.get('retcodes') and test_results['retcodes'][-1] !=0....

[Ziqi Xiong, 2016/08/09 18:59:11]

Done.

+        api.m.chromium.c.TARGET_PLATFORM == 'android'): #pragma: no cover
+      api.m.chromium_android.device_status()

[sullivan, 2016/08/08 22:13:28]

What does device_status() do?

[Ziqi Xiong, 2016/08/09 18:59:11]

It rechecks the devices connected to host and then updates
api.m.chromium_android.devices.

+      current_connected_devices = api.m.chromium_android.devices
+      current_device = api.m.bisect_tester.device_to_test
+      if current_device not in current_connected_devices:
+        raise api.m.step.StepFailure('Test device disconnected.')
     if self.bisector.is_return_code_mode():
       retcodes = test_results['retcodes']
       self.overall_return_code = 0 if all(v == 0 for v in retcodes) else 1