1"""Test to ensure we're not touching /dev/ptmx when running commands."""
2
3from __future__ import print_function
4
5import os
6import subprocess
7import tempfile
8import time
9import unittest
10from cros_utils import command_executer
11
12
13class NoPsuedoTerminalTest(unittest.TestCase):
14  """Test to ensure we're not touching /dev/ptmx when running commands."""
15
16  _strace_process = None
17  STRACE_TIMEOUT = 10
18
19  def _AttachStraceToSelf(self, output_file):
20    """Attaches strace to the current process."""
21    args = ['strace', '-o', output_file, '-p', str(os.getpid())]
22    print(args)
23    self._strace_process = subprocess.Popen(args)
24    # Wait until we see some activity.
25    start_time = time.time()
26    while time.time() - start_time < self.STRACE_TIMEOUT:
27      if os.path.isfile(output_file) and open(output_file).read(1):
28        return True
29      time.sleep(1)
30    return False
31
32  def _KillStraceProcess(self):
33    """Kills strace that was started by _AttachStraceToSelf()."""
34    self._strace_process.terminate()
35    self._strace_process.wait()
36    return True
37
38  def testNoPseudoTerminalWhenRunningCommand(self):
39    """Test to make sure we're not touching /dev/ptmx when running commands."""
40    temp_file = tempfile.mktemp()
41    self.assertTrue(self._AttachStraceToSelf(temp_file))
42
43    ce = command_executer.GetCommandExecuter()
44    ce.RunCommand('echo')
45
46    self.assertTrue(self._KillStraceProcess())
47
48    strace_contents = open(temp_file).read()
49    self.assertFalse('/dev/ptmx' in strace_contents)
50
51
52if __name__ == '__main__':
53  unittest.main()
54