public RingbufferConfig setBackupCount(int backupCount) {
        this.backupCount = checkBackupCount(backupCount, asyncBackupCount);
        return this;
    }
@Test(expected = IllegalArgumentException.class)
    public void setBackupCount_whenTooSmall() {
        RingbufferConfig config = new RingbufferConfig(NAME);

        config.setBackupCount(-1);
    }