#lang racket (require 2htdp/universe) (require 2htdp/image) (define (f x) (circle 10 'solid 'red)) (define (g x) (cond [(= x 0) 1] [else (error txt)])) (define txt "all questions were #f") (with-handlers ([exn? (lambda (e) (unless (string=? (exn-message e) txt) (raise e)))]) (big-bang 0 (on-tick g) (to-draw f)) (error 'error-in-tick "test failed"))