Migrate and merge logging_utils from swarming_bot into client/utils.

appengine/swarming/swarming_bot/logging_utils_test.py

-#!/usr/bin/env python
-# Copyright 2014 The Swarming Authors. All rights reserved.
-# Use of this source code is governed by the Apache v2.0 license that can be
-# found in the LICENSE file.
-
-import logging
-import os
-import sys
-import tempfile
-import shutil
-import unittest
-import re
-
-# Import this first before manipulating sys.path to ensure it can load fine.
-import logging_utils
-
-ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-sys.path.insert(0, ROOT_DIR)
-
-import test_env
-test_env.setup_test_env()
-
-from depot_tools import auto_stub
-
-_LOG_HEADER = r'^%s \d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d\.\d\d\d: ' % os.getpid()
-
-
-class TestLoggingUtils(auto_stub.TestCase):
-  def test_Capture(self):
-    root = logging.RootLogger(logging.DEBUG)
-    with logging_utils.CaptureLogs('foo', root) as log:
-      root.debug('foo')
-      result = log.read()
-    self.assertTrue(re.match(_LOG_HEADER + 'DEBUG foo\n$', result), result)
-
-  def test_prepare_logging(self):
-    root = logging.RootLogger(logging.DEBUG)
-    tmp_dir = tempfile.mkdtemp(prefix='logging_utils_test')
-    try:
-      filepath = os.path.join(tmp_dir, 'test.log')
-      logging_utils.prepare_logging(filepath, root)
-      root.debug('foo')
-      with open(filepath, 'rb') as f:
-        result = f.read()
-    finally:
-      shutil.rmtree(tmp_dir)
-    # It'd be nice to figure out a way to ensure it's properly in UTC but it's
-    # tricky to do reliably.
-    self.assertTrue(re.match(_LOG_HEADER + 'DEBUG foo\n$', result), result)
-
-
-if __name__ == '__main__':
-  unittest.main()