如何为约束顺序中的一系列操作创建test.check生成器？

Question

(require '[clojure.test.check.generators :as gen])

(def ACTIONS
  {:create-new-user #{}
   :edit-user #{:create-new-user}
   :create-new-board #{:create-new-user}
   :edit-board #{:create-new-board}
   :create-new-anonymous-comment #{:create-new-board}
   :create-new-signed-comment #{:create-new-board}
   :edit-comment-text #{:create-new-anonymous-comment :create-new-signed-comment}
   :edit-comment-text-and-flip-anonymity #{:create-new-anonymous-comment :create-new-signed-comment}
   :flip-anonymity #{:create-new-anonymous-comment :create-new-signed-comment}
   :vote-comment-up #{:create-new-anonymous-comment :create-new-signed-comment}
   :vote-comment-down #{:create-new-anonymous-comment :create-new-signed-comment}})

(def actions (-> ACTIONS keys vec gen/elements gen/vector))

(defn filter-actions-into-logical-order [as]
  (let [seen (atom #{})]
    (filter
     (fn [v]
       (let [required (get ACTIONS v)
             valid? (or (some? (some required @seen)) 
                        (and (empty? @seen) (= v :create-new-user)))]
         (when valid?
           (swap! seen conj v)
           true)))
     as)))

(def ordered-actions (gen/fmap #(-> % filter-actions-into-logical-order vec)  actions))

以这两个生成器为例：

# (last (gen/sample actions 100))
[:edit-user :vote-comment-down :flip-anonymity :vote-comment-down :vote-comment-down :vote-comment-up :edit-user :create-new-anonymous-comment :edit-board :create-new-signed-comment :vote-comment-up :edit-comment-text-and-flip-anonymity :edit-user :create-new-signed-comment :edit-user :edit-user :vote-comment-down :edit-user :vote-comment-down :create-new-user :vote-comment-down :create-new-user :create-new-user :edit-comment-text-and-flip-anonymity :create-new-user :edit-comment-text-and-flip-anonymity :create-new-anonymous-comment :edit-comment-text :create-new-board :vote-comment-down :flip-anonymity :create-new-signed-comment :vote-comment-up :create-new-user :create-new-signed-comment :edit-user :create-new-user :create-new-board :vote-comment-down :create-new-board :create-new-board :create-new-board :edit-board :edit-comment-text-and-flip-anonymity :edit-user :edit-comment-text :create-new-signed-comment :vote-comment-up :edit-comment-text-and-flip-anonymity :flip-anonymity :create-new-anonymous-comment :create-new-anonymous-comment :edit-board :create-new-signed-comment :edit-comment-text-and-flip-anonymity :edit-board :vote-comment-up :edit-comment-text :create-new-board :edit-comment-text-and-flip-anonymity :create-new-board :vote-comment-down :edit-comment-text-and-flip-anonymity :vote-comment-up :create-new-user :vote-comment-up :edit-comment-text :edit-board :edit-comment-text-and-flip-anonymity :flip-anonymity :edit-board :create-new-anonymous-comment :flip-anonymity :create-new-signed-comment :edit-user :edit-comment-text-and-flip-anonymity :edit-comment-text :edit-comment-text :create-new-user :flip-anonymity :edit-user :vote-comment-up :edit-user :create-new-user :edit-comment-text :edit-comment-text :flip-anonymity :edit-comment-text :edit-board :flip-anonymity :edit-board :edit-comment-text :edit-user :create-new-user :flip-anonymity]


# (last (gen/sample ordered-actions 100))
[:create-new-user :edit-user :edit-user :create-new-board :edit-board :edit-user :create-new-anonymous-comment :edit-comment-text :edit-board :edit-user :edit-user :vote-comment-up :edit-comment-text :create-new-signed-comment :edit-comment-text :create-new-board :edit-comment-text :edit-comment-text :edit-comment-text :vote-comment-up :vote-comment-up :edit-board :edit-comment-text-and-flip-anonymity :create-new-signed-comment :create-new-anonymous-comment :create-new-signed-comment :edit-user :create-new-anonymous-comment :edit-board :create-new-board :create-new-anonymous-comment :create-new-board :flip-anonymity :create-new-anonymous-comment :edit-board :vote-comment-up :vote-comment-down :edit-board :edit-comment-text :edit-user :edit-comment-text :flip-anonymity :create-new-signed-comment :vote-comment-up :edit-comment-text-and-flip-anonymity :vote-comment-up :create-new-signed-comment :edit-comment-text :create-new-signed-comment :create-new-anonymous-comment :edit-board :create-new-anonymous-comment]

ACTIONS是一个映射，其中键是操作的名称，值是该操作的(基于OR的)依赖项。例如，您必须先执行:create-new-user，然后才能执行任何操作，必须先执行:create-new-board，然后才能执行:edit-board，并且必须至少有一个:create-new-*-comment才能执行:edit-comment-text。

上面的代码似乎可以工作，但它很难看。1)我不喜欢filter-actions-into-logical-order代码必须对:create-new-user有一个特定的异常。2)我不喜欢我基本上采用随机操作的列表，并将其过滤，直到这些操作有顺序的意义。

我想知道其他人是如何使用test.check生成这样的一系列动作的？肯定有一种只使用生成器就能做到这一点的方法？

Answer 1

使用使用gen/bind的递归生成器来实现这一点并不太难(例如，首先生成操作列表的大小，然后使用gen/bind在该大小上使用递归，以便在每一步都有先前生成的操作)。这种方法的最大缺点是，gen/bind在收缩方面的工作相当糟糕，因此您可能会得到几乎根本不能收缩的长序列操作。

我真的很想为此想出更好的办法。

Answer 2

可以说，如果改用reduce，filter-into-logical-order可能会更干净

(defn filter-into-logical-order [as]
  (last (reduce
         (fn [[seen accepted-as] action]
           (let[needed (get ACTIONS action)]
             (if (or (empty? needed) (some seen needed))
               [(conj seen action) (conj accepted-as action)]
               [seen accepted-as]))
           )
         [#{} []]
         as)))

但这仍然为我提供了大约30%的空向量，而且它不是一个生成器。不过，我不确定文档中的组合子是否真的支持您想要的内容。gen/vector似乎不支持将构造中的向量传递给它的内部生成器，这样它就可以知道允许什么值，这是您的需求所需的某种结构。