Suspecting a bug in org.scalatest.concurrent.AsynchronousAssertions.Waiter. The code below fails pretty reliably. There seems to be a window of vulnerability in awaitImpl(): if the last (or last few) dismiss() calls happen after the dismissals count test at the top of the while() loop, but the associated notifyAll() invocations happen before the…

WaiterSpec.scala

package scratch

// scalatest 2.0.M8

import org.scalatest.WordSpec
import org.scalatest.matchers.ShouldMatchers
import org.scalatest.concurrent.AsyncAssertions
import org.scalatest.time.{ Span, Millis }

class WaiterSpec extends WordSpec with ShouldMatchers with AsyncAssertions {
  "A Waiter instance" should {
    "not break when beaten on" in {
      val n = 100000
      val w = new Waiter
      new Thread(new Runnable {
        override def run(): Unit = {
          var i = 0
          while (i < n) { w.dismiss(); i += 1 }
          println(s"i=$i")
        }
      }).start
      w.await(timeout(Span(2000, Millis)), dismissals(n))
    }
  }
}

Sorry it took me a while to get enough focused time to study this. I think your reasoning makes sense. Can you submit a pull request?

Also we have added instructions on building ScalaTest to the scalatest.org site and the github project. With the advent of Scala 2.10.3 it has become much easier (because of a memory-leak fix in the Scala compiler that affected ScalaTest badly). Previously I couldn't build it with sbt on my laptop with 8Gb (though I could with ant)! Now the sbt build works fine in much less memory, so I'd recommend using that instead of ant now. We also as of this morning made a tweak that enables ScalaTest to be built on JDK 7 as well as JDK6. The problem was that some Swing classes, which were raw in JDK6, were generified in JDK7. We had to use code gen to deal with that, but that was another thing that made ScalaTest hard to build.

Thanks.

Bill

Huzzah! Scalatest built and tests ran ok. Instructions were a big help. (Yeah I'd discovered the memory and JDK-7 issues.)

Now working on integrating my fix.

OK, pull request made. Happy to iterate if necessary.