public void CanCalculateUsdCashAccountMultipleTimes()
{
var testContext = new AccountTestContext();
testContext.Create(Workspace, AccountService);
testContext.MakeUsdSale(100);
var usdBalance = AccountDao.GetAccountExchangeBalance(testContext.UsdCashAccount.Id);
Assert.AreEqual(100, usdBalance);
var saleBalance = AccountDao.GetAccountExchangeBalance(testContext.SaleAccount.Id);
Assert.AreEqual(-200, saleBalance);
}