领域模型测试与核心原则总结
1. 领域模型属性验证
在领域模型中，我们可以通过定义一些属性来验证业务规则。以账户（Account）模型为例，首先来看账户的抽象定义以及相关代数数据类型：
import java.util.{ Date, Calendar } object common { type Amount = BigDecimal def today = Calendar.getInstance.getTime } import common._ case class Balance(amount: Amount = 0) sealed trait Account { def no: String def name: String def dateOfOpen: Option[Date] def dateOfClose: Option[Date] def balance: Balance } final case class CheckingAccount (no: String, name: String, dateOfOpen: Option[Date], dateOfClose: Option[Date] = None, balance: Balance = Balance()) extends Account final case class SavingsAccount (no: String, name: String, rateOfInterest: Amount, dateOfOpen: Option[Date], dateOfClose: