clojure - 什么是 Clojure 中的生成测试？

Question

我遇到了 Generative Testing in Clojure with spec概念，并想了解它。

还提供一些示例将非常有用。

Answer 1

作为介绍性阅读，我们有 Rationale and Overview随着Guide这应该为您提供有关原因和方式的信息。

如果你想要一个有点复杂的例子，我们可以使用 string->semantic-version leiningen.release 的功能:

(defn string->semantic-version [version-string]
  "Create map representing the given version string. Returns nil if the
  string does not follow guidelines setforth by Semantic Versioning 2.0.0,
  http://semver.org/"
  ;; <MajorVersion>.<MinorVersion>.<PatchVersion>[-<Qualifier>][-SNAPSHOT]
  (if-let [[_ major minor patch qualifier snapshot]
           (re-matches
            #"(\d+)\.(\d+)\.(\d+)(?:-(?!SNAPSHOT)([^\-]+))?(?:-(SNAPSHOT))?"
            version-string)]
    (->> [major minor patch]
         (map #(Integer/parseInt %))
         (zipmap [:major :minor :patch])
         (merge {:qualifier qualifier
                 :snapshot snapshot}))))

它接受一个字符串并尝试将其解析为一个程序可读的映射，该映射表示某个工件的版本号。它的规范可能如下所示:

首先是一些依赖

(ns leiningen.core.spec.util
  (:require
   [clojure.spec           :as spec]
   [clojure.spec.gen       :as gen]
   [miner.strgen           :as strgen]
   [clojure.spec.test      :as test]
   [leiningen.release      :as release]))

然后是一个辅助宏

(defmacro stregex
  "Defines a spec which matches a string based on a given string
  regular expression. This the classical type of regex as in the
  clojure regex literal #\"\""
  [string-regex]
  `(spec/with-gen
     (spec/and string? #(re-matches ~string-regex %))
     #(strgen/string-generator ~string-regex)))

后跟语义版本的定义

(spec/def ::semantic-version-string
  (stregex #"(\d+)\.(\d+)\.(\d+)(-\w+)?(-SNAPSHOT)?"))

和一些辅助规范

(spec/def ::non-blank-string
  (spec/and string? #(not (str/blank? %))))
(spec/def ::natural-number
  (spec/int-in 0 Integer/MAX_VALUE))

用于定义结果映射中的键

(spec/def ::release/major     ::natural-number)
(spec/def ::release/minor     ::natural-number)
(spec/def ::release/patch     ::natural-number)
(spec/def ::release/qualifier ::non-blank-string)
(spec/def ::release/snapshot  #{"SNAPSHOT"})

和 map 本身

(spec/def ::release/semantic-version-map
  (spec/keys :req-un [::release/major ::release/minor ::release/patch
                      ::release/qualifier ::release/snapshot]))

其次是功能规范:

(spec/fdef release/string->semantic-version
           :args (spec/cat :version-str ::release/semantic-version-string)
           :ret  ::release/semantic-version-map)

现在我们可以让 Clojure Spec 生成测试数据并将其提供给函数本身，以测试它是否满足我们为其设置的约束:

(test/check `release/version-map->string)
=> ({:spec #object[clojure.spec$fspec_impl$reify__14248 0x16c2555 "clojure.spec$fspec_impl$reify__14248@16c2555"],
     :clojure.spec.test.check/ret {:result true,
                                   :num-tests 1000,
                                   :seed 1491922864713},
     :sym leiningen.release/version-map->string})

这告诉我们，在为我们生成的 1000 个测试用例规范中，该函数通过了每一个。