def METHOD_NAME(root_path):
    """
    Test the content append modes.
    """
    # create initial content
    with root_path["appendfile"].open("wb") as fil:
        fil.write(b"just")
    # append some data
    with root_path["appendfile"].open("ab") as fil:
        assert_value(fil.readable(), False)
        assert_value(fil.writable(), True)
        fil.write(b" some")
    # append some more data and then read it
    with root_path["appendfile"].open("arb") as fil:
        assert_value(fil.readable(), True)
        assert_value(fil.writable(), True)
        fil.write(b" test")
    # use the read-write mode to first read, then write, then read.
    with root_path["appendfile"].open("rwb") as fil:
        assert_value(fil.readable(), True)
        assert_value(fil.writable(), True)
        assert_value(fil.read(), b"just some test")
        fil.seek(0)
        fil.write(b"overwritten")
        fil.seek(0)
        assert_value(fil.read(), b"overwrittenest")