我有一个简单的应用程序，模拟资金从一个帐户转移到另一个帐户。我想写一个测试来证明它不是线程安全的。
有一种可能性，线程将以这样的方式运行，即传输将被执行两次。双线程场景：
acc1=1000$
acc2=0$
转移600$
t1:获取acc1余额（1000）
t2：获取acc1余额（1000）
t1：从account1（400）中减去600美元
t2：从account2（400）中减去600美元
t1:将acc2增加600$（600）
t2:增加acc2 600$（1200）
目前我的应用程序不支持多线程，它应该失败，这是我现在的罚款。我可以用调试器模拟错误。然而，当我做线程测试时，它总是成功的。我尝试了不同数量的线程，睡眠，可调用任务

@Test
    public void testTransfer() throws AccountNotFoundException, NotEnoughMoneyException, InterruptedException {
        Callable<Boolean> callableTask = () -> {
            try {
                moneyTransferService.transferMoney(ACCOUNT_NO_1, ACCOUNT_NO_2, TRANSFER_AMOUNT);
                return true;
            } catch (AccountNotFoundException | NotEnoughMoneyException e) {
                e.printStackTrace();
                return false;
            }
        };

        List<Callable<Boolean>> callableTasks = new ArrayList<>();
        int transferTries = 2;
        for(int i = 0; i <= transferTries; i++) {
            callableTasks.add(callableTask);
        }

        ExecutorService executorService = Executors.newFixedThreadPool(2);
        executorService.invokeAll(callableTasks);

        Assert.assertEquals(ACCOUNT_BALANCE_1.subtract(TRANSFER_AMOUNT), accountRepository.getByAccountNumber(ACCOUNT_NO_1).get().getBalance());
        Assert.assertEquals(ACCOUNT_BALANCE_2.add(TRANSFER_AMOUNT), accountRepository.getByAccountNumber(ACCOUNT_NO_2).get().getBalance());
    }

以下是汇款代码：

public void transferMoney(String accountFrom, String accountTo, BigDecimal amount) throws AccountNotFoundException, NotEnoughMoneyException {
        Account fromAccount = getAccountByNumber(accountFrom);
        Account toAccount = getAccountByNumber(accountTo);

        if (isBalanceSufficient(amount, fromAccount)) {

            //TODO this should be thread safe and transactional
            BigDecimal fromNewAmount = fromAccount.getBalance().subtract(amount);
            fromAccount.setBalance(fromNewAmount);

            // it's possible to fail junits with sleep but I dont want it in code obviously
//          Random random = new Random();
//          try {
//              Thread.sleep(random.nextInt(100));
//          } catch (InterruptedException e) {
//              // TODO Auto-generated catch block
//              e.printStackTrace();
//          }

            BigDecimal toNewAmount = toAccount.getBalance().add(amount);
            toAccount.setBalance(toNewAmount);

        } else {
            throw new NotEnoughMoneyException("Balance on account: " + fromAccount.getNumber() + " is not sufficient to transfer: " + amount);//TODO add currency
        }
    }