[nomerge] Cleanup threads created by parallel collections tests

Author: retronym

build.sbt

@@ -581,6 +581,9 @@ lazy val scalacheck = project.in(file("test") / "scalacheck")
   .settings(
     fork in Test := false,
     javaOptions in Test += "-Xss1M",
+    testOptions += Tests.Cleanup { loader =>
+      ModuleUtilities.getObject("scala.TestCleanup", loader).asInstanceOf[Runnable].run()
+    },
     libraryDependencies ++= Seq(scalacheckDep),
     unmanagedSourceDirectories in Compile := Nil,
     unmanagedSourceDirectories in Test := List(baseDirectory.value)

test/scalacheck/scala/pc.scala

@@ -38,9 +38,21 @@ class ParCollProperties extends Properties("Parallel collections") {
   val ectasks = new collection.parallel.ExecutionContextTaskSupport(ec)
   includeAllTestsWith(ectasks, "ectasks")
 
-  // no post test hooks in scalacheck, so cannot do:
-  // ec.shutdown()
+  // no post test hooks in scalacheck, so the best we can do is:
+  TestCleanup.register(ec.shutdown())
+}
+
 
+object TestCleanup extends Runnable {
+  private val cleanups = scala.collection.mutable.Buffer[() => Unit]()
+  def register(action: => Any) = synchronized {
+    cleanups += {() => action}
+  }
+  // called by the SBT build. Scalacheck doesn't have any native support for cleanup
+  override def run(): Unit = {
+    cleanups.foreach(_.apply())
+    cleanups.clear()
+  }
 }
 
 /*