Insert logcat as part of test result for android instrumentation tests.

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

 # Copyright 2015 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 logging
 import os
 import posixpath
 import re
 import time
 
@@ skipping 245 matching lines @@
       self._CreateFlagChangerIfNeeded(device)
       self._flag_changers[str(device)].PushFlags(
         add=flags.add, remove=flags.remove)
 
     try:
       device.RunShellCommand(
           ['log', '-p', 'i', '-t', _TAG, 'START %s' % test_name],
           check_return=True)
       time_ms = lambda: int(time.time() * 1e3)
       start_ms = time_ms()
-      output = device.StartInstrumentation(
-          target, raw=True, extras=extras, timeout=timeout, retries=0)
+      output_file = '/tmp/logcat/%s' % test_name

[jbudorick, 2016/10/25 22:11:33]

Use tempfile.NamedTemporaryFile as a context manager instead of doing this:
https://docs.python.org/2/library/tempfile.html#tempfile.NamedTemporaryFile

+      with device.GetLogcatMonitor(output_file=output_file) as logmon:
+        output = device.StartInstrumentation(
+            target, raw=True, extras=extras, timeout=timeout, retries=0)
+      logmon.Close()
+      logcat = open(output_file, 'r').read()
+      os.remove(output_file)
     finally:
       device.RunShellCommand(
           ['log', '-p', 'i', '-t', _TAG, 'END %s' % test_name],
           check_return=True)
       duration_ms = time_ms() - start_ms
       if flags:
         self._flag_changers[str(device)].Restore()
       if test_timeout_scale:
         valgrind_tools.SetChromeTimeoutScale(
             device, self._test_instance.timeout_scale)
 
     # TODO(jbudorick): Make instrumentation tests output a JSON so this
     # doesn't have to parse the output.
     result_code, result_bundle, statuses = (
         self._test_instance.ParseAmInstrumentRawOutput(output))
     results = self._test_instance.GenerateTestResults(
         result_code, result_bundle, statuses, start_ms, duration_ms)
+    for result in results:
+      result.SetLogcat(logcat)
 
     # Update the result name if the test used flags.
     if flags:
       for r in results:
         if r.GetName() == test_name:
           r.SetName(test_display_name)
 
     # Add UNKNOWN results for any missing tests.
     iterable_test = test if isinstance(test, list) else [test]
     test_names = set(self._GetUniqueTestName(t) for t in iterable_test)
@@ skipping 85 matching lines @@
         timeout = v
         break
     else:
       logging.warning('Using default 1 minute timeout for %s', test_name)
       timeout = 60
 
     timeout *= cls._GetTimeoutScaleFromAnnotations(annotations)
 
     return timeout