Scala: assertThrows in Junit5 and hand-rolled

assertThrows.scala

def throwingFunction(): Unit = throw RuntimeError()

// own implementation of assertThrows
def assertThrows[E](f: => Unit)(implicit eType:ClassTag[E]): Unit =
  try f
  catch
    case _: E => return
    case e: Any => Assertions.fail(s"Expected ${eType.runtimeClass.getName} got ${e.getClass}")
  Assertions.fail(s"Expected ${eType.runtimeClass.getName}")

// usage:
assertThrows[RuntimeError](throwingFunction())

// import assertThrows from jupiter/JUnit5
import org.junit.jupiter.api.Assertions

// usage:
Assertions.assertThrows(classOf[RuntimeError], () => throwingFunction())

tbh I like my implementation better, but if you are able to use JUnit5, it is preferable to use the library function.

JUnit4 does not offer an assertThrows, so you may have to use the own implementation.