// Verify format contains expected memory units
        assertTrue(log.matches(".*used [0-9.]+[a-zA-Z]+, heap [0-9.]+[a-zA-Z]+, max [0-9.]+[a-zA-Z]+.*"));
    }

    public void test_byteCountToDisplaySize_edgeCases() {
        // Test negative values - should throw NullPointerException in private method via BigInteger.valueOf
        try {
            MemoryUtil.byteCountToDisplaySize(-1L);