import kotlin.test.fail

inline fun <reified T: Throwable>assertThrows(f: ()->Unit): T {
    val name = T::class.simpleName
    try {
        f()
        fail("expected to throw $name but threw nothing")
    }
    catch(x: Throwable) {
        if( x is T ) return x
        fail("expected to throw $name but instead threw ${x::class.simpleName}: $x")
    }
}