我在使用 ScalaTest 时遇到了一个很难调试的错误。奇怪的是,当我的程序没有 Main 对象时,似乎会发生这种情况,但当它有 Main 对象时,却不会发生这种情况。我的代码实际上只是使用带有多态方法的类型类从列表中获取切片,看起来像这样(对稍微冗长的示例表示歉意,我已尽可能地减少了它):
package sportarray
object ArrayDefs {
abstract class IsArr[A, I0, DT] {
def getElem(self: A, i: Int): DT
def getSlice[R](self: A, r: R)(implicit sliceTc: IsSlice[R]): sliceTc.Out = sliceTc.getSlice(self, r)
trait IsSlice[R] {
type Out
def getSlice(self: A, ref: R): Out
}
object IsSlice {
implicit val iLocTCForInt = new IsSlice[Int] {
type Out = DT
def getSlice(self: A, ref: Int): Out = getElem(self, ref)
}
implicit val iLocTCForList = new IsSlice[List[Int]] {
type Out = List[DT]
def getSlice(self: A, ref: List[Int]): Out = ref.map(getElem(self, _))
}
}
}
object IsArrSyntax {
implicit class IsArrOps[A, I0, T](self: A)(implicit
tc1d: IsArr[A, I0, T]
) {
def getElem(i: Int) = tc1d.getElem(self, i)
def getSlice[R](r: R)(implicit sliceTc: tc1d.IsSlice[R]) = tc1d.getSlice(self, r)
}
}
}
object ListOfListsObj {
import ArrayDefs._
case class List1d[I0, T] (
indices: List[I0],
data: List[T],
)
implicit def list1dIs1dSpArr[A, I0, T] =
new IsArr[List1d[I0, T], I0, T] {
def getElem(self: List1d[I0, T], i: Int) = self.data(i)
}
}
我的测试很简单,看起来像这样,在测试目录中自己的文件中:
package sportarray
import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers
class ArraySpec extends AnyFlatSpec with Matchers {
"List" should "act as an array" in {
import ArrayDefs._
import ArrayDefs.IsArrSyntax._
import ListOfListsObj._
val list1d = List1d[Int, Double](List(1,2,3), List(1.0, 2.0, 3.0))
assert(list1d.getSlice(1) == 2.0)
}
}
If I sbt test
这段代码是这样的,我收到以下错误:
java.lang.NoSuchFieldError: sportarray$ArrayDefs$IsArrSyntax$IsArrOps$$tc1d
at sportarray.ArraySpec.$anonfun$new$1(HelloSpec.scala:12)
at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
at org.scalatest.Transformer.apply(Transformer.scala:22)
at org.scalatest.Transformer.apply(Transformer.scala:20)
at org.scalatest.flatspec.AnyFlatSpecLike$$anon$5.apply(AnyFlatSpecLike.scala:1683)
然后,我尝试向程序添加一个 Main 类,看看这是测试的问题,还是代码本身的问题:
object Main extends App {
import ArrayDefs._
import ArrayDefs.IsArrSyntax._
import ListOfListsObj._
val list1d = List1d[Int, Double](List(1,2,3), List(1.0, 2.0, 3.0))
assert(list1d.getSlice(1) == 2.0)
}
如果我这样的话效果很好sbt run
,而且,奇怪的是,还允许我运行sbt test
没有任何问题。如果我然后删除这个主类,sbt test
再次失败。有人能够阐明这里发生的事情吗?
谢谢你的帮助!