def METHOD_NAME(self, fpath):
    """
    test nacl.dec function
    with keyfile and pk_file set
    """
    with salt.utils.files.fopen(fpath, "w") as wfh:
        wfh.write(self.key)
    with salt.utils.files.fopen(fpath + ".pub", "w") as wfh:
        wfh.write(self.pub)
    kwargs = {
        "opts": {"pki_dir": os.path.dirname(fpath)},
        "keyfile": fpath,
        "pk_file": fpath + ".pub",
    }
    enc_data = nacl.enc("blah", **kwargs)
    ret = nacl.dec(enc_data, **kwargs)
    assert isinstance(ret, bytes)
    assert ret == b"blah"