scala - 使用 ScalaTest 时出现 java.lang.NoSuchFieldError

Question

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 对象时则不会。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(对于稍微冗长的示例，我已经尽可能地减少了它):

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，在测试目录中它自己的文件中:

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)
  }
}

如果我 sbt test这段代码，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 sbt run，这可以正常工作，而且，奇怪的是，还允许我运行 sbt test没有任何问题。如果我删除这个主类， sbt test再次失败。有没有人能够解释这里发生了什么？
谢谢你的帮助!

Answer 1

其实我ran来自命令行的 Scalatest 并且它成功了

$ scalac -cp .:scalactic_2.13-3.2.2.jar:scalatest_2.13-3.2.2.jar:scalatest-core_2.13-3.2.2.jar:scalatest-flatspec_2.13-3.2.2.jar:scalatest-matchers-core_2.13-3.2.2.jar:scalatest-shouldmatchers_2.13-3.2.2.jar:scalatest-compatible-3.2.2.jar App.scala AppTest.scala 
$ scala -cp .:scalactic_2.13-3.2.2.jar:scalatest_2.13-3.2.2.jar:scalatest-core_2.13-3.2.2.jar:scalatest-flatspec_2.13-3.2.2.jar:scalatest-matchers-core_2.13-3.2.2.jar:scalatest-shouldmatchers_2.13-3.2.2.jar:scalatest-compatible-3.2.2.jar:scala-xml_2.13-1.3.0.jar org.scalatest.run AppTest
Run starting. Expected test count is: 1
AppTest:
List
- should act as an array
Run completed in 151 milliseconds.
Total number of tests run: 1
Suites: completed 1, aborted 0
Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
All tests passed.

在 IntelliJ 和 sbt 中它失败了:
(IntelliJ)

An exception or error caused a run to abort: App$ArrayDefs$IsArrSyntax$IsArrOps$$tc1d
java.lang.NoSuchFieldError: App$ArrayDefs$IsArrSyntax$IsArrOps$$tc1d
    at AppTest.$anonfun$new$1(AppTest.scala:10)
    at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
    at org.scalatest.OutcomeOf.outcomeOf$(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$$anon$5.apply(AnyFlatSpecLike.scala:1683)
    at org.scalatest.TestSuite.withFixture(TestSuite.scala:196)
    at org.scalatest.TestSuite.withFixture$(TestSuite.scala:195)
    at org.scalatest.flatspec.AnyFlatSpec.withFixture(AnyFlatSpec.scala:1685)
    at org.scalatest.flatspec.AnyFlatSpecLike.invokeWithFixture$1(AnyFlatSpecLike.scala:1681)
    at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$runTest$1(AnyFlatSpecLike.scala:1693)
    at org.scalatest.SuperEngine.runTestImpl(Engine.scala:306)
    at org.scalatest.flatspec.AnyFlatSpecLike.runTest(AnyFlatSpecLike.scala:1693)
    at org.scalatest.flatspec.AnyFlatSpecLike.runTest$(AnyFlatSpecLike.scala:1675)
    at org.scalatest.flatspec.AnyFlatSpec.runTest(AnyFlatSpec.scala:1685)
    at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$runTests$1(AnyFlatSpecLike.scala:1751)
    at org.scalatest.SuperEngine.$anonfun$runTestsInBranch$1(Engine.scala:413)
    at scala.collection.immutable.List.foreach(List.scala:333)
    at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
    at org.scalatest.SuperEngine.runTestsInBranch(Engine.scala:390)
    at org.scalatest.SuperEngine.$anonfun$runTestsInBranch$1(Engine.scala:427)
    at scala.collection.immutable.List.foreach(List.scala:333)
    at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
    at org.scalatest.SuperEngine.runTestsInBranch(Engine.scala:396)
    at org.scalatest.SuperEngine.runTestsImpl(Engine.scala:475)
    at org.scalatest.flatspec.AnyFlatSpecLike.runTests(AnyFlatSpecLike.scala:1751)
    at org.scalatest.flatspec.AnyFlatSpecLike.runTests$(AnyFlatSpecLike.scala:1750)
    at org.scalatest.flatspec.AnyFlatSpec.runTests(AnyFlatSpec.scala:1685)
    at org.scalatest.Suite.run(Suite.scala:1112)
    at org.scalatest.Suite.run$(Suite.scala:1094)
    at org.scalatest.flatspec.AnyFlatSpec.org$scalatest$flatspec$AnyFlatSpecLike$$super$run(AnyFlatSpec.scala:1685)
    at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$run$1(AnyFlatSpecLike.scala:1796)
    at org.scalatest.SuperEngine.runImpl(Engine.scala:535)
    at org.scalatest.flatspec.AnyFlatSpecLike.run(AnyFlatSpecLike.scala:1796)
    at org.scalatest.flatspec.AnyFlatSpecLike.run$(AnyFlatSpecLike.scala:1794)
    at org.scalatest.flatspec.AnyFlatSpec.run(AnyFlatSpec.scala:1685)
    at org.scalatest.tools.SuiteRunner.run(SuiteRunner.scala:45)
    at org.scalatest.tools.Runner$.$anonfun$doRunRunRunDaDoRunRun$13(Runner.scala:1320)
    at org.scalatest.tools.Runner$.$anonfun$doRunRunRunDaDoRunRun$13$adapted(Runner.scala:1314)
    at scala.collection.immutable.List.foreach(List.scala:333)
    at org.scalatest.tools.Runner$.doRunRunRunDaDoRunRun(Runner.scala:1314)
    at org.scalatest.tools.Runner$.$anonfun$runOptionallyWithPassFailReporter$24(Runner.scala:993)
    at org.scalatest.tools.Runner$.$anonfun$runOptionallyWithPassFailReporter$24$adapted(Runner.scala:971)
    at org.scalatest.tools.Runner$.withClassLoaderAndDispatchReporter(Runner.scala:1480)
    at org.scalatest.tools.Runner$.runOptionallyWithPassFailReporter(Runner.scala:971)
    at org.scalatest.tools.Runner$.run(Runner.scala:798)
    at org.scalatest.tools.Runner.run(Runner.scala)
    at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.runScalaTest2or3(ScalaTestRunner.java:40)
    at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.main(ScalaTestRunner.java:27)

(sbt)

[error] java.lang.NoSuchFieldError: App$ArrayDefs$IsArrSyntax$IsArrOps$$tc1d
[error]     at AppTest.$anonfun$new$1(AppTest.scala:10)
[error]     at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[error]     at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[error]     at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[error]     at org.scalatest.Transformer.apply(Transformer.scala:22)
[error]     at org.scalatest.Transformer.apply(Transformer.scala:20)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike$$anon$5.apply(AnyFlatSpecLike.scala:1683)
[error]     at org.scalatest.TestSuite.withFixture(TestSuite.scala:196)
[error]     at org.scalatest.TestSuite.withFixture$(TestSuite.scala:195)
[error]     at org.scalatest.flatspec.AnyFlatSpec.withFixture(AnyFlatSpec.scala:1685)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.invokeWithFixture$1(AnyFlatSpecLike.scala:1681)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$runTest$1(AnyFlatSpecLike.scala:1693)
[error]     at org.scalatest.SuperEngine.runTestImpl(Engine.scala:306)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.runTest(AnyFlatSpecLike.scala:1693)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.runTest$(AnyFlatSpecLike.scala:1675)
[error]     at org.scalatest.flatspec.AnyFlatSpec.runTest(AnyFlatSpec.scala:1685)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$runTests$1(AnyFlatSpecLike.scala:1751)
[error]     at org.scalatest.SuperEngine.$anonfun$runTestsInBranch$1(Engine.scala:413)
[error]     at scala.collection.immutable.List.foreach(List.scala:333)
[error]     at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
[error]     at org.scalatest.SuperEngine.runTestsInBranch(Engine.scala:390)
[error]     at org.scalatest.SuperEngine.$anonfun$runTestsInBranch$1(Engine.scala:427)
[error]     at scala.collection.immutable.List.foreach(List.scala:333)
[error]     at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
[error]     at org.scalatest.SuperEngine.runTestsInBranch(Engine.scala:396)
[error]     at org.scalatest.SuperEngine.runTestsImpl(Engine.scala:475)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.runTests(AnyFlatSpecLike.scala:1751)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.runTests$(AnyFlatSpecLike.scala:1750)
[error]     at org.scalatest.flatspec.AnyFlatSpec.runTests(AnyFlatSpec.scala:1685)
[error]     at org.scalatest.Suite.run(Suite.scala:1112)
[error]     at org.scalatest.Suite.run$(Suite.scala:1094)
[error]     at org.scalatest.flatspec.AnyFlatSpec.org$scalatest$flatspec$AnyFlatSpecLike$$super$run(AnyFlatSpec.scala:1685)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$run$1(AnyFlatSpecLike.scala:1796)
[error]     at org.scalatest.SuperEngine.runImpl(Engine.scala:535)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.run(AnyFlatSpecLike.scala:1796)
[error]     at org.scalatest.flatspec.AnyFlatSpecLike.run$(AnyFlatSpecLike.scala:1794)
[error]     at org.scalatest.flatspec.AnyFlatSpec.run(AnyFlatSpec.scala:1685)
[error]     at org.scalatest.tools.Framework.org$scalatest$tools$Framework$$runSuite(Framework.scala:318)
[error]     at org.scalatest.tools.Framework$ScalaTestTask.execute(Framework.scala:513)
[error]     at sbt.TestRunner.runTest$1(TestFramework.scala:139)
[error]     at sbt.TestRunner.run(TestFramework.scala:154)
[error]     at sbt.TestFramework$$anon$3$$anonfun$$lessinit$greater$1.$anonfun$apply$1(TestFramework.scala:317)
[error]     at sbt.TestFramework$.sbt$TestFramework$$withContextLoader(TestFramework.scala:277)
[error]     at sbt.TestFramework$$anon$3$$anonfun$$lessinit$greater$1.apply(TestFramework.scala:317)
[error]     at sbt.TestFramework$$anon$3$$anonfun$$lessinit$greater$1.apply(TestFramework.scala:317)
[error]     at sbt.TestFunction.apply(TestFramework.scala:329)
[error]     at sbt.Tests$.$anonfun$toTask$1(Tests.scala:311)
[error]     at sbt.std.Transform$$anon$3.$anonfun$apply$2(Transform.scala:46)
[error]     at sbt.std.Transform$$anon$4.work(Transform.scala:67)
[error]     at sbt.Execute.$anonfun$submit$2(Execute.scala:281)
[error]     at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:19)
[error]     at sbt.Execute.work(Execute.scala:290)
[error]     at sbt.Execute.$anonfun$submit$1(Execute.scala:281)
[error]     at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:178)
[error]     at sbt.CompletionService$$anon$2.call(CompletionService.scala:37)
[error]     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[error]     at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[error]     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[error]     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[error]     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[error]     at java.lang.Thread.run(Thread.java:748)
[error] (Test / executeTests) java.lang.NoSuchFieldError: App$ArrayDefs$IsArrSyntax$IsArrOps$$tc1d

所以问题似乎是 IntelliJ 和 sbt 如何运行 Scalatest。
NoSuchFieldError Java
Java NoSuchFieldError when using Reflection
https://github.com/unicredit/hbase-rdd/issues/21