容器的Scalatest隐式相等

我们定义了一个自定义的

相等[String]

：

implicit val upperCaseEquality = new Equality[String] {
  override def areEqual(self: String, b: Any): Boolean = b match {
    case other: String => self.toUpperCase == other.toUpperCase
    case _ => false
  }
}

以下代码正常工作：

Seq("a").view should contain theSameElementsInOrderAs Seq("A")

现在，我们为

Seq

添加了一个自定义的

Equality

：

implicit def SeqEquality[T, SEQ[e] <: GenSeq[e]](implicit equality: Equality[T]): Equality[SEQ[T]] = new Equality[SEQ[T]] {
  override def areEqual(self: SEQ[T], b: Any): Boolean = b match {
    case other: GenSeq[_] => self.size == other.size && self.zip(other).forall(equality.areEqual _ tupled)
    case _ => false
    }
}

assert(Seq("a") === Seq("A"))

但不适用于

SeqView

：

assert(Seq("a").view === Seq("A"))

Exception in thread "main" org.scalatest.exceptions.TestFailedException: SeqView("a") did not equal List("A")

为什么？

如果您看到：

您可以看到，

SeqView[\u，\u]

实际上有两个类型参数，因此它不符合您的规范

SEQ[e]
def view(from: Int, until: Int): SeqView[A, Seq[A]]

implicit def SeqViewEquality[T](implicit equality: Equality[T]): Equality[SeqView[T, Seq[T]]] = new Equality[SeqView[T, Seq[T]]] {
  override def areEqual(self: SeqView[T, Seq[T]], b: Any): Boolean = b match {
    case other: GenSeq[_] => self.size == other.size && self.zip(other).forall(equality.areEqual _ tupled)
    case _ => false
  }
}