old_contents: import os
  import socket
  import threading
  
  import pytest
  
  pytest_plugins = 'pytester',
  
  
  @pytest.fixture(params=[[], ['--', 'python', '-c', 'print("success")']])
  def extra(request):
      return request.param
  
  
  def test_normal(testdir, extra):
      tcp = socket.socket()
      tcp.bind(('127.0.0.1', 0))
      tcp.listen(1)
      _, port = tcp.getsockname()
      t = threading.Thread(target=tcp.accept)
      t.start()
  
      tcp = socket.socket(socket.AF_UNIX)
      if os.path.exists('/tmp/holdup-test.sock'):
          os.unlink('/tmp/holdup-test.sock')
      tcp.bind('/tmp/holdup-test.sock')
      tcp.listen(1)
      result = testdir.run(
          'holdup',
          '-t', '0.5',
          'tcp://localhost:%s' % port,
          'unix:///tmp/holdup-test.sock',
          *extra
      )
      if extra:
          result.stdout.fnmatch_lines(['success'])
      t.join()
  
  
  def test_no_abort(testdir, extra):
      result = testdir.run(
          'holdup',
          '-t', '0.1',
          '-n',
          'tcp://localhost:0',
          'unix:///doesnt/exist',
          *extra
      )
      result.stderr.fnmatch_lines(['Failed checks: tcp://localhost:0, unix:///doesnt/exist'])
  
new_contents: import os
  import socket
  import threading
  
  import pytest
  
  pytest_plugins = 'pytester',
  
  
  @pytest.fixture(params=[[], ['--', 'python', '-c', 'print("success")']])
  def extra(request):
      return request.param
  
  
  def test_normal(testdir, extra):
      tcp = socket.socket()
      tcp.bind(('127.0.0.1', 0))
      tcp.listen(1)
      _, port = tcp.getsockname()
      t = threading.Thread(target=tcp.accept)
      t.start()
  
      tcp = socket.socket(socket.AF_UNIX)
      if os.path.exists('/tmp/holdup-test.sock'):
          os.unlink('/tmp/holdup-test.sock')
      tcp.bind('/tmp/holdup-test.sock')
      tcp.listen(1)
      result = testdir.run(
          'holdup',
          '-t', '0.5',
          'tcp://localhost:%s' % port,
          'unix:///tmp/holdup-test.sock',
          *extra
      )
      if extra:
          result.stdout.fnmatch_lines(['success'])
      t.join()
  
  
  def test_no_abort(testdir, extra):
      result = testdir.run(
          'holdup',
          '-t', '0.1',
          '-n',
          'tcp://localhost:0',
          'unix:///doesnt/exist',
          *extra
      )
      result.stderr.fnmatch_lines(['Failed checks: tcp://localhost:0 ([[]Errno 111[]]*), unix:///doesnt/exist ([[]Errno 2[]]*)'])
  
subject: Update assertions.