如何使用ScalaTest匹配器测试属性是否满足指定条件而非相等性？

问题翻译 #

可以用have来检查属性是否等于某个值，有没有办法不检查相等性，而是验证属性是否满足某个匹配器？下面的代码能编译但无法正常工作，因为它是在把属性和匹配器值做相等性测试：

import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers

class MainTest extends AnyFlatSpec with Matchers {
  case class Book(title: String, author: List[String], pubYear: Int)
  "Something" should "work" in {
    val book = Book("Programming in Scala", List("Odersky", "Spoon", "Venners"), 2008)
    book should have (
      Symbol("title") ("Programming in Scala"),
      Symbol("pubYear") (be >= 2006 and be <= 2010)
    )
  }
}

解决方案 #

你需要用matching方法包裹匹配器，让have验证属性是否满足匹配器规则，而非做相等性对比。修改后的代码如下：

import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers

class MainTest extends AnyFlatSpec with Matchers {
  case class Book(title: String, author: List[String], pubYear: Int)
  "Something" should "work" in {
    val book = Book("Programming in Scala", List("Odersky", "Spoon", "Venners"), 2008)
    book should have (
      'title ("Programming in Scala"),
      'pubYear matching (be >= 2006 and be <= 2010)
    )
  }
}

如果觉得更直观，也可以拆分属性验证逻辑：

book should have ('title ("Programming in Scala"))
book.pubYear should (be >= 2006 and be <= 2010)

要是需要更复杂的自定义属性校验，还可以创建PropertyMatcher：

val pubYearInRange = new PropertyMatcher[Book] {
  def apply(book: Book) = MatchResult(
    book.pubYear >= 2006 && book.pubYear <= 2010,
    s"出版年份${book.pubYear}不在2006-2010区间内",
    s"出版年份${book.pubYear}符合2006-2010区间要求"
  )
}

// 使用示例
book should have (pubYearInRange)

内容的提问来源于stack exchange，提问作者Suma