ScalaでTry-with-resourceの実装例。https://medium.com/@dkomanov/scala-try-with-resources-735baad0fd7d の実装例のテスト。類似の仕組みについては、 このあたりにまとまっている。http://www.ne.jp/asahi/hishidama/home/tech/scala/sample/using.html#h_loan_pattern

ScalaTryWithResourceExampleTest .scala

package jp.seraphyware.example

import java.io.IOException

import org.junit.Test

import jp.seraphyware.example.ScalaTryWithResourcesExample._

/**
  * テストクラス
  */
class ScalaTryWithResourceExampleTest {

  /**
    * クローズ時に例外を出せるテスト用リソース
    *
    * @param raiseError クローズ時に例外を出すか？
    */
  private class TestResource(private val raiseError: Boolean) extends AutoCloseable {
    println("constructor")

    override def close(): Unit = {
      println("close")
      if (raiseError) {
        println("exception when closing!")
        throw new RuntimeException("TEST=EXCEPTION")
      }
    }
  }

  @Test
  def testBlockNorm(): Unit = {
    println("★Loan patten★")
    withResources(new TestResource(false)) {
      _ =>
    }
  }

  @Test(expected = classOf[IOException])
  def testBlockExcept(): Unit = {
    println("★Loan patten (exception)★")
    withResources(new TestResource(false)) {
      _ => throw new IOException("brake!!")
    }
  }

  @Test(expected = classOf[IOException])
  def testBlockDblExcept(): Unit = {
    println("★Loan patten (finally-exception)★")
    withResources(new TestResource(true)) {
      _ => throw new IOException("brake!!")
    }
  }
}

ScalaTryWithResourcesExample.scala

package jp.seraphyware.example

import scala.util.control.NonFatal

/**
  * Java7以降のTry-With-Resource構文と同等な処理のScalaでの実装例。
  * https://medium.com/@dkomanov/scala-try-with-resources-735baad0fd7d
  */
object ScalaTryWithResourcesExample {

  def withResources[T <: AutoCloseable, V](r: => T)(f: T => V): V = {
    val resource: T = r
    require(resource != null, "resource is null")
    var exception: Throwable = null
    try {
      f(resource)
    } catch {
      case NonFatal(e) =>
        exception = e
        throw e
    } finally {
      closeAndAddSuppressed(exception, resource)
    }
  }

  private def closeAndAddSuppressed(e: Throwable, resource: AutoCloseable): Unit = {
    if (e != null) {
      try {
        resource.close()
      } catch {
        case NonFatal(suppressed) =>
          e.addSuppressed(suppressed)
      }
    } else {
      resource.close()
    }
  }
}