[Telemetry] Fix WPR files not being downloaded when required.

tools/telemetry/telemetry/wpr/archive_info.py

Index: tools/telemetry/telemetry/wpr/archive_info.py
diff --git a/tools/telemetry/telemetry/wpr/archive_info.py b/tools/telemetry/telemetry/wpr/archive_info.py
index c94bd7ba6f6117f1a295484ed4df843cf52115e2..2cf54823da51cbf062ae9ac109a8dad5189b1680 100644
--- a/tools/telemetry/telemetry/wpr/archive_info.py
+++ b/tools/telemetry/telemetry/wpr/archive_info.py
@@ -73,12 +73,9 @@ class WprArchiveInfo(object):
     exists.
     """
     # Download all .wpr files.
-    if self._data:

[aiolos (Not reviewing), 2015/01/13 19:42:58]

I believe this should actually be

if not self._data:

Because we assume self.data_ in the next code section.

[nednguyen, 2015/01/13 19:58:51]

lizeb@'s point is self._data cannot be None since FromFile is the constructor
method to be used. If it's just empty, then self._data['archives'] will throw
exception. Anyway, I asked lizeb@ to add the assertion that 'archives' in
self._data.

[aiolos (Not reviewing), 2015/01/13 20:18:57]

Ah, I missed that comment. We might rely on this not throwing exceptions on
archives with no data for some testing bits. If it fails in the CQ, we should
look into whether any of those assumption are valid, and may need to adjust some
tests.

The name of the function is slightly misleading if we added the assertion, and
should at the very least have it's doc updated to reflect that it will fail the
assert if self.data_ is empty.

-      return
     if not self._bucket:
       logging.warning('User story set in %s has no bucket specified, and '
                       'cannot be downloaded from cloud_storage.', )

[nednguyen, 2015/01/13 18:20:59]

Can you add: assert 'archives' in self._data, "Invalid data from file %s' %
self._file_path ?

[Benoit L, 2015/01/13 18:24:39]

Acknowledged.

The constructor would throw without 'archives' in self._data.

[nednguyen, 2015/01/13 18:38:14]

I prefer assertion since it gives a clearer debugging message. Also you get to
know the name of the file that contains invalid data that debug message.

-
     for archive_path in self._data['archives']:
       archive_path = self._WprFileNameToPath(archive_path)
       try: