def METHOD_NAME(self,
                     cmd=None,
                     config="packetbeat.yml",
                     output=None,
                     extra_args=[],
                     debug_selectors=[]):
    """
    Starts packetbeat and returns the process handle. The
    caller is responsible for stopping / waiting for the
    Proc instance.
    """
    if output is None:
        output = "packetbeat-" + self.today + ".ndjson"
    if cmd is None:
        cmd = self.beat_path + "/packetbeat.test"
    args = [cmd,
            "-e",
            "-c", os.path.join(self.working_dir, config),
            "-systemTest",
            ]
    if os.getenv("TEST_COVERAGE") == "true":
        args += [
            "-test.coverprofile", os.path.join(self.working_dir, "coverage.cov"),
        ]
    if extra_args:
        args.extend(extra_args)
    if debug_selectors:
        args.extend(["-d", ",".join(debug_selectors)])
    proc = Proc(args, os.path.join(self.working_dir, output))
    proc.start()
    return proc