[swarming/api] Add text in to indicate whether a shard is failing

scripts/slave/recipe_modules/swarming/api.py

Index: scripts/slave/recipe_modules/swarming/api.py
diff --git a/scripts/slave/recipe_modules/swarming/api.py b/scripts/slave/recipe_modules/swarming/api.py
index 8bc0bb3a696c2e0ac960e197f8dc0b9cd2cd2b7d..e6da43ee60201a9fb4e338264982c8a3f7b07107 100644
--- a/scripts/slave/recipe_modules/swarming/api.py
+++ b/scripts/slave/recipe_modules/swarming/api.py
@@ -847,8 +847,12 @@ class SwarmingApi(recipe_api.RecipeApi):
         links = step_result.presentation.links
         for index in xrange(task.shards):
           url = task.get_shard_view_url(index)
+          if summary['shards'][index].get('exit_code', 0) != 0:

[nednguyen, 2016/09/22 15:54:40]

I get to know this by looking at an example summary.json output, i.e:
python swarming.py collect -S https://chromium-swarm.appspot.com
--task-output-dir=foo 30bc1911e6720a10

cat foo/summary.json

Do we have documentation/code pointer about what summary.json is supposed to
contain somewhere?

[M-A Ruel, 2016/09/22 16:05:02]

No. :/

[Vadim Sh., 2016/09/22 17:36:30]

Please also handle a case when summary['shards'][index] is None. 

I think it can happen if Swarming client has trouble collecting the results
(e.g. network timeouts). Though maybe dying with AttributeError is good enough
in this case...

On 2016/09/22 16:05:02, M-A Ruel wrote:
I believe each dict in 'shards' list has the structure of TaskResult protorpc
message:
https://github.com/luci/luci-py/blob/master/appengine/swarming/swarming_rpcs....

(based on https://github.com/luci/luci-py/blob/master/client/swarming.py#L547)

[nednguyen, 2016/09/22 21:03:54]

Done. However I am missing the code coverage. You have any suggestion how to add
test to cover the case a shard return None?

+            display_text = 'shard #%d (failed)' % index
+          else:
+            display_text = 'shard #%d' % index
           if url:
-            links['shard #%d' % index] = url
+            links[display_text] = url
 
         step_result.isolated_script_results = \
           self._merge_isolated_script_shards(task, step_result)