new_contents: from subprocess import Popen, PIPE
  
  
  TOOL = 'crosslinking_bot'
  
  
  def run_tool(args=[]):
      p = Popen([TOOL] + args, stdout=PIPE, stderr=PIPE)
      stdout, stderr = (out.decode('utf-8') for out in p.communicate())
      return p, stdout, stderr
  
  def test_simple_call():
      p, stdout, stderr = run_tool()
      assert p.returncode == 0
  
  
  
subject: Add E2E test (close #13)