[Android] Log uncaught Java exceptions when running native tests.

build/android/pylib/local/device/local_device_gtest_run.py

 # Copyright 2014 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.
 
 import collections
 import itertools
+import logging
 import os
 import posixpath
 
 from devil.android import device_errors
 from devil.android import device_temp_file
 from devil.android import ports
 from devil.utils import reraiser_thread
 from pylib import constants
 from pylib.base import base_test_result
 from pylib.gtest import gtest_test_instance
@@ skipping 287 matching lines @@
       tests = _ExtractTestsFromFilter(self._test_instance.gtest_filter)
       if tests:
         return tests
 
     # Even when there's only one device, it still makes sense to retrieve the
     # test list so that tests can be split up and run in batches rather than all
     # at once (since test output is not streamed).
     @local_device_test_run.handle_shard_failures_with(
         on_failure=self._env.BlacklistDevice)
     def list_tests(dev):
-      tests = self._delegate.Run(
+      raw_test_list = self._delegate.Run(
           None, dev, flags='--gtest_list_tests', timeout=30)
-      tests = gtest_test_instance.ParseGTestListTests(tests)
+      tests = gtest_test_instance.ParseGTestListTests(raw_test_list)
+      if not tests:
+        logging.info('No tests found. Output:')
+        for l in raw_test_list:
+          logging.info('  %s', l)
       tests = self._test_instance.FilterTests(tests)
       return tests
 
     # Query all devices in case one fails.
     test_lists = self._env.parallel_devices.pMap(list_tests).pGet(None)
 
     # If all devices failed to list tests, raise an exception.
     # Check that tl is not None and is not empty.
     if all(not tl for tl in test_lists):
       raise device_errors.CommandFailedError(
@@ skipping 29 matching lines @@
   def TearDown(self):
     @local_device_test_run.handle_shard_failures
     def individual_device_tear_down(dev):
       for s in self._servers.get(str(dev), []):
         s.TearDown()
 
       tool = self.GetTool(dev)
       tool.CleanUpEnvironment()
 
     self._env.parallel_devices.pMap(individual_device_tear_down)