(defmethod clojure.test/assert-expr 'working? [msg form]
  (let [body (next form)]
    `(do ~@body
         (clojure.test/do-report {:type :pass, :message ~msg,
                                  :expected :success, :actual :success}))))

(is (working? (+ 1 2 3))) ;; works
(is (working? (throw (ex-info "" {})))) ;; doesn't work