assert fail throws Boxed Error

[aleagnelli]

When this code is executed I get a Boxed Error, which can be confusing

class Test extends munit.FunSuite {

  case class Inner(value: Double)

  case class Outer(data: Seq[Inner])

  test("exist issue") {
    val values = Array(
      Outer(Seq(Inner(1), Inner(2), Inner(10))),
      Outer(Seq(Inner(1), Inner(2), Inner(10))),
      Outer(Seq(Inner(1), Inner(2), Inner(10)))
    )
    assert(values.exists(outer => outer.data.exists(inner => inner.value > 90)))
  }

}

Result:

java.util.concurrent.ExecutionException: Boxed Error

    at scala.concurrent.impl.Promise$.resolver(Promise.scala:87)
    at scala.concurrent.impl.Promise$.scala$concurrent$impl$Promise$$resolveTry(Promise.scala:79)
    at scala.concurrent.impl.Promise$KeptPromise$.apply(Promise.scala:406)
    at scala.concurrent.Promise$.fromTry(Promise.scala:142)
    at scala.concurrent.Future$.fromTry(Future.scala:640)
    at munit.ValueTransforms.munitValueTransform(ValueTransforms.scala:37)
    at munit.ValueTransforms.munitValueTransform$(ValueTransforms.scala:22)
    at munit.FunSuite.munitValueTransform(FunSuite.scala:11)
    at munit.FunSuite.$anonfun$test$1(FunSuite.scala:37)
    at munit.MUnitRunner.$anonfun$runTestBody$1(MUnitRunner.scala:290)
Caused by: munit.FailException: /home/ale/workspace/munit_issue/src/test/scala/Test.scala:13 assertion failed
12:    )
13:    assert(values.exists(outer => outer.data.exists(inner => inner.value > 90)))
14:  }
    at munit.FunSuite.assert(FunSuite.scala:11)
    at Test.$anonfun$new$1(Test.scala:13)
    at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)

Expected:

munit.FailException: /home/ale/workspace/munit_issue/src/test/scala/Test.scala:13 assertion failed
12:    )
13:    assert(values.exists(outer => outer.data.exists(inner => inner.value > 90)))
14:  }

    at munit.FunSuite.assert(FunSuite.scala:11)
    at Test.$anonfun$new$1(Test.scala:13)
    at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)

If the assertion return true everything works as expected
munit version: 0.7.19
scala version: 2.11.12, 2.12.12

scala version 2.13.4 works as expected

[gabro]

Hi @alexagnelli, thanks for reporting. This is due to how Future handles subclasses of java.lang.Error:

ExecutionException - stored when the computation fails due to an unhandled InterruptedException, Error or a scala.util.control.ControlThrowable. In this case the ExecutionException has the unhandled exception as its cause. The rationale behind this is to prevent propagation of critical and control-flow related exceptions normally not handled by the client code and at the same time inform the client in which future the computation failed.

from https://docs.scala-lang.org/overviews/core/futures.html

Ultimately this is caused by MUnit's exceptions extending AssertionError, which in turn extends Error.

I've tried digging a bit into this, but I couldn't spot an easy way to get rid of the intermediate ExecutionException when reporting the error. I'm open to suggestions if somebody more expert than me on the matter wants to chime in.

[aleagnelli]

Hi @gabro, thank you for digging up so quickly.
There is still one thing that is not clear to me: in scala 2.13.4 the Error is handled as expected, but I didn't find any change in Future behavior's, any idea what is happening different?

The only thing I found is:

Futures were internally redesigned, with these goals:

provide expected behavior under a broader set of failure conditions

https://github.com/scala/scala/releases/tag/v2.13.0

[gabro]

@alexagnelli the only thing related there is the handling of InterruptedException (which is similar in fashion) by the ExecutionContext. I suspect something similar has been done for Error but I couldn't pinpoint the specific diff after a quick look

[olafurpg]

Thank you for reporting! I actually had a pending fix for this issue in 265769e (#225) but didn't merge the PR #225. I opened #277 with a cherry-pick of that commit