Take desktop screenshots after test failures in test_runner.py.

ios/build/bots/scripts/test_runner.py

 # Copyright 2016 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.
 
 """Test runners for iOS."""
 
 import argparse
 import collections
 import errno
 import os
@@ skipping 270 matching lines @@
     else:
       parser = gtest_utils.GTestLogParser()
 
     proc = subprocess.Popen(
         cmd,
         env=self.get_launch_env(),
         stdout=subprocess.PIPE,
         stderr=subprocess.STDOUT,
     )
 
+    failed_test_count = len(parser.FailedTests())
     while True:
       line = proc.stdout.readline()
       if not line:
         break
       line = line.rstrip()
       parser.ProcessLine(line)
       print line
       sys.stdout.flush()
 
+      # If there is a new test failure, take screenshot of desktop. This can
+      # help with debugging failures on the bots.
+      if len(parser.FailedTests()) > failed_test_count:
+        failed_test_count = len(parser.FailedTests())
+        self.screenshot_desktop()

[smut, 2017/03/22 22:46:54]

parser is reinitialized every time (lines 279-282) so on line 291
failed_test_count will always be zero. Line 301 can then be "if
parser.FailedTests():".

[baxley, 2017/03/22 23:24:39]

Done.

[baxley, 2017/03/23 13:54:19]

I don't think this works. parser is initialized outside of the while loop, so
once there is a test failure then a screenshot is taken for every line of
output. When running ios-simulator try job it fails due to not enough space. I
reverted to the mode where I count failures and only take a screenshot when it
increases.

Is the documents directory cleaned up after each suite on simulator (I thought
it was, but want to confirm). This will store on the order of 1MB per
screenshot.

+
     proc.wait()
     sys.stdout.flush()
 
     for test in parser.FailedTests(include_flaky=True):
       # Test cases are named as <test group>.<test case>. If the test case
       # is prefixed with "FLAKY_", it should be reported as flaked not failed.
       if '.' in test and test.split('.', 1)[1].startswith('FLAKY_'):
         result.flaked_tests[test] = parser.FailureDescription(test)
       else:
         result.failed_tests[test] = parser.FailureDescription(test)
@@ skipping 450 matching lines @@
     """
     env = super(DeviceTestRunner, self).get_launch_env()
     if self.xctest_path:
       env['NSUnbufferedIO'] = 'YES'
       # e.g. ios_web_shell_egtests
       env['APP_TARGET_NAME'] = os.path.splitext(
           os.path.basename(self.app_path))[0]
       # e.g. ios_web_shell_egtests_module
       env['TEST_TARGET_NAME'] = env['APP_TARGET_NAME'] + '_module'
     return env