Awwww that's cheating :disappointed: those were made private on purpose.  I did some cleanup on another test and came up with this, feel free to duplicate it or similar:

    def signal_container(self, name):
        dc = self.sub_stuff['dc']
        sig = getattr(signal, self.config['listen_signal'])
        self.loginfo("Signaling container %s with %s(%d)",
                     name, self.config['listen_signal'], sig)
        json = dc.json_by_name(name)
        self.failif(not json[0]["State"]["Running"],
                    "Can't signal non-running container, see debug "
                    "log for more detail")
        pid = int(json[0]["State"]["Pid"])
        self.failif(not utils.signal_pid(pid, sig),
                    "Failed to cause container exit with signal: "
                    "still running, see debug log for more detail.")