How to fork the jvm for each test in sbt

sbt, scala

Solution

It turns out this is fairly easy to achieve. The documentation is sufficient and can be found at Testing - Forking tests

// Define a method to group tests, in my case a single test per group
def singleTests(tests: Seq[TestDefinition]) =
  tests map { test =>
    new Group(
      name = test.name,
      tests = Seq(test),
      runPolicy = SubProcess(javaOptions = Seq.empty[String]))
  }

// Add the following to the `Project` settings
testGrouping in Test <<= definedTests in Test map singleTests

Problem

I am working with some classes that (for some reason) can only be used once within a single VM. My test cases work if I run them individually (`fork := true`) enabled in my `sbt` settings. If I run more than one of these tests, they fail with an exception that has to with a thread executor rejecting a task (it's most likely closed). It would be very time consuming to find out what causes the problem and even if I find the problem, I might not be able to resolve it (I do not have access to the source code). I am currently using the `specs2` test framework, but any test framework using `sbt` would be acceptable. Is there any test framework for `sbt` that is capable of running each test in a `jvm` fork? Thoughts or ideas on possible other solutions are of course welcome.

Original source