초기 코드@Testvoid calculateBalance_ShouldReturnCorrectBalance() { AccountId accountId = new AccountId(1L); // Given // 1P has a balance of 100 Account account = AccountTestData.defaultAccount() .withAccountId(accountId) .withBaselineBalance(Money.of(100L)) .withActivityWindow(new ActivityWindow( // 2P send 200 money to 1P ActivityTestDa..