an [IndexOutOfBoundsException] should be thrownBy s.charAt(-1)

val thrown = the [IndexOutOfBoundsException] should be thrownBy s.charAt(-1)
thrown.getMessage should equal ("String index out of range: -1") 

the [ArithmeticException] thrown by 1 / 0 should have message "/by zero"
the [IndexOutOfBoundsException] thrownBy {
    s.charAt(-1)
} should have message "String index out of range: -1"