Setting up multiple test folders in a SBT project

We'd like to set up our SBT project so that we have multip开发者_如何学Cle test folders as opposed to one. So we'd like to see:

• root
  • src
    • test
    • scala
    • unit
    • functional

How would we configure our SBT project file paths to do this?

SBT 0.9.x:

(sourceDirectories in Test) := Seq(new File("src/test/scala/unit"), 
                                   new File("src/test/scala/functional"))

SBT 0.7.x:

override def testSourceRoots = ("src" / "test") +++ 
       "scala" +++ ("unit" / "functional")