import kotlin.reflect.* import kotlin.reflect.jvm.* import kotlin.test.assertEquals class A { private fun foo() = "A" } fun box(): String { val f = A::class.declaredFunctions.single() as KFunction try { f.call(A()) return "Fail: no exception was thrown" } catch (e: IllegalCallableAccessException) {} f.isAccessible = true assertEquals("A", f.call(A())) return "OK" }