    @Test
    public void testIncrement() {

        IdGenerator testGenerator = new IdGenerator(IdAlphabets.COLLECTION_ID, true);

        String[] inputs = new String[]{
                "0000",
                "A",
                "AZ00",
                "Az00",
                "Zz00",
                "zz00",
                "zzz0",
                "zzzz"
        };

        for (String input : inputs) {
            verifyIncrement(input, testGenerator.increment(input, 2));
        }

        for (int i = 0; i < 50; i++) {
            String input = testGenerator.longToPaddedIdentifier(RANDOM.nextLong());
            verifyIncrement(input, testGenerator.increment(input, RANDOM.nextInt(input.length())));
        }
    }