So I was trying to unit testing Scala Futures, and I was getting NullPointerException out of nowhere. I was frustrated since the stacktrace didn't much more information, not a minimal clue of what was missing. It was until I payed attention to some other examples when I realized that I was missing something important:
import ExecutionContext.Implicits.global
I do not know why it wasn't detected at compile time, or why the exception was only coming as NullPointerException without any other hint. My test is something like this:
"Some test" should {
"execute this" in {
val client = mock[AClass]
val host = new BClass(client)
doReturn(Future {x}).when(client).aMethod(any[String], any[String]) // This was throwing a NPE
val response = host.anyMethod(cI, mA, bL)
Await.result(response, Duration(30, SECONDS))
there was one(client). aMethod(any[String], any[String])
}
}
