(register-test '(suite "Error Tests"
  ("'ensuring gets called on the way out"
   (let x 10
        (ensure (assign x (+ x 11))
                (assign x (+ x 22)))
        x)
   43)

  ("'on-err handles errors"
   (let x nil
        (on-err (= x "impossible")
                (= x (nil nil nil)))
        x)
   "impossible")

  ("'on-err handles errors but any ensuring clause gets called first"
   (with (x nil y nil)
        (on-err (= x 'impossible)
                (ensure (assign y 'ensure-clause)
                        (nil nil nil)))
        (list x y))
   (impossible ensure-clause))))