Have service_manager start a cloudtail attached to each service it starts.

infra/libs/service_utils/test/_daemon_nix_test.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 contextlib
 import collections
 import errno
 import os
 import sys
 import unittest
@@ skipping 161 matching lines @@
 
   def testClosesFdWithExceptions(self, _mock_exit, _mock_chdir, _mock_dup2,
                                  _mock_open, mock_close, _mock_setsid,
                                  _mock_fork):
     daemon.become_daemon(keep_fds={42})
 
     self.assertEqual(2047, mock_close.call_count)
     self.assertEqual([((i,),) for i in reversed(range(2048)) if i != 42],
                      mock_close.call_args_list)
 
+  def testClosesFdsKeepingAll(self, _mock_exit, _mock_chdir, _mock_dup2,
+                              _mock_open, mock_close, _mock_setsid,
+                              _mock_fork):
+    daemon.become_daemon(keep_fds=True)
+
+    self.assertEqual(0, mock_close.call_count)
+
   def testClosesInvalidFds(self, _mock_exit, _mock_chdir, _mock_dup2,
                            _mock_open, mock_close, _mock_setsid, _mock_fork):
     mock_close.side_effect = EnvironmentError(errno.EIO, '')
     with self.assertRaises(EnvironmentError):
       daemon.become_daemon()
 
     mock_close.side_effect = EnvironmentError(errno.EBADF, '')
     daemon.become_daemon()
 
   def testOpensDevNull(self, _mock_exit, _mock_chdir, mock_dup2, mock_open,
                        _mock_close, _mock_setsid, _mock_fork):
     handle = object()
     mock_open.return_value = handle
 
     daemon.become_daemon()
 
     self.assertEqual([
         ((handle, 0),),
         ((handle, 1),),
         ((handle, 2),),
     ], mock_dup2.call_args_list)
 
+  def testOpensDevNullWithExceptions(self, _mock_exit, _mock_chdir, mock_dup2,
+                                     mock_open, _mock_close, _mock_setsid,
+                                     _mock_fork):
+    handle = object()
+    mock_open.return_value = handle
+
+    daemon.become_daemon(keep_fds={1})
+
+    self.assertEqual([
+        ((handle, 0),),
+        ((handle, 2),),
+    ], mock_dup2.call_args_list)
+
   def testChangesToRoot(self, _mock_exit, mock_chdir, _mock_dup2, _mock_open,
                         _mock_close, _mock_setsid, _mock_fork):
     daemon.become_daemon()
     mock_chdir.assert_called_with('/')
 
   def testForkExitsParent(self, mock_exit, _mock_chdir, _mock_dup2, _mock_open,
                           _mock_close, _mock_setsid, mock_fork):
     mock_fork.return_value = 0
     daemon.become_daemon()
     self.assertFalse(mock_exit.called)
 
     mock_fork.return_value = 123
     daemon.become_daemon()
     self.assertTrue(mock_exit.called)