#lang imperative-syndicate/test-implementation
;; An error signalled mid-turn must cause previous actions to be
;; discarded; discarded actions must not be observed by peers.

(test-case
    [(message-struct set-box (new-value))
     (assertion-struct box-state (value))

     (spawn (field [current-value 0])
            (assert (box-state (current-value)))
            (on (message (set-box $new-value)) (current-value new-value))
            (begin/dataflow (when (= (current-value) 3)
                              (error 'box "aiee"))))

     (spawn (on (asserted (box-state $v)) ;; must not see 3 here.
                (printf "~v\n" v)
                (send! (set-box (+ v 1)))))]
  (expected-output (list "0"
                         "1"
                         "2")))