BigInteger balance1 = repository.getBalance(Hex.decode(addr));
repository.addBalance(Hex.decode(addr), BigInteger.valueOf(300));
BigInteger balance2 = repository.getBalance(Hex.decode(addr));
repository.addBalance(Hex.decode(addr), BigInteger.valueOf(-150));
BigInteger balance3 = repository.getBalance(Hex.decode(addr));
assertEquals(0, balance0.intValue());
assertEquals(0, balance1.intValue());
assertEquals(300, balance2.intValue());