functionpreviously cljs.spec/exerciseEdit
(exercise spec)
(exercise spec n)
(exercise spec n overrides)

Source docstring:
generates a number (default 10) of values compatible with spec and maps conform over them,
returning a sequence of [val conformed-val] tuples. Optionally takes
a generator overrides map as per gen
Source code @ clojurescript:src/main/cljs/cljs/spec/alpha.cljs
(defn exercise
  ([spec] (exercise spec 10))
  ([spec n] (exercise spec n nil))
  ([spec n overrides]
   (map #(vector % (conform spec %)) (gen/sample (gen spec overrides) n))))