spec-failing-with-gen.clj

;;;; Works

(ns workflo.macros.scratch
  (:require #?(:cljs [cljs.spec :as s]
               :clj  [clojure.spec :as s])
            [clojure.test.check.generators :as gen]))

(s/def ::item
  symbol?)

(s/def ::pair
  (s/cat :base ::item
         :children ::items))

(s/def ::item-or-pair
  (s/alt :item ::item
         :pair ::pair))

(s/def ::items
  (s/and vector?
         (s/* ::item-or-pair)))

(println (s/conform ::items '[foo bar [baz ruux]]))
;; Success!
(println (s/explain ::items '[foo bar [baz ruux]]))
;; nil




;;;; Does not work

(ns workflo.macros.scratch
  (:require #?(:cljs [cljs.spec :as s]
               :clj  [clojure.spec :as s])
            [clojure.test.check.generators :as gen]))

(s/def ::item
  symbol?)

(s/def ::pair
  (s/with-gen
    (s/cat :base ::item
           :children ::items)
    #(gen/tuple (s/gen ::item)
                (s/gen ::items))))

(s/def ::item-or-pair
  (s/alt :item ::item
         :pair ::pair))

(s/def ::items
  (s/and vector?
         (s/* ::item-or-pair)))

(println (s/conform ::items '[foo bar [baz ruux]]))
;; :clojure.spec/invalid
(println (s/explain ::items '[foo bar [baz ruux]]))
;; In: [2] val: [baz ruux] fails spec: :workflo.macros.scratch/item at: [:item] predicate: symbol?
;; In: [2 1] val: ruux fails spec: :workflo.macros.scratch/items at: [:pair :workflo.macros.scratch/children] predicate: vector?