'``run_process`` returns a `__ProcessResult`` object with the status,
command and combined stdout and stderr if the exit status is 0.'

def test_success(self):

    command = self.command_for_test(returncode=0)
    result = run_process(command.commandline())
    self.assertEqual(_ProcessResult(command=command.commandline(), status=command.returncode, output=(command.stdout + command.stderr)), result)
