我的数据有复杂的Spec - 如何生成样本？

Question

我的Clojure规范看起来像：

(spec/def ::global-id string?)
(spec/def ::part-of string?)
(spec/def ::type string?)
(spec/def ::value string?)
(spec/def ::name string?)
(spec/def ::text string?)
(spec/def ::date (spec/nilable (spec/and string? #(re-matches #"^\d{4}-\d{2}-\d{2}$" %))))
(spec/def ::interaction-name string?)
(spec/def ::center (spec/coll-of string? :kind vector? :count 2))
(spec/def ::context- (spec/keys :req [::global-id ::type]
                                :opt [::part-of ::center]))
(spec/def ::contexts (spec/coll-of ::context-))
(spec/def ::datasource string?)
(spec/def ::datasource- (spec/nilable (spec/keys :req [::global-id ::name])))
(spec/def ::datasources (spec/coll-of ::datasource-))
(spec/def ::location string?)
(spec/def ::location-meaning- (spec/keys :req [::global-id ::location ::contexts ::type]))
(spec/def ::location-meanings (spec/coll-of ::location-meaning-))
(spec/def ::context string?)
(spec/def ::context-association-type string?)
(spec/def ::context-association-name string?)
(spec/def ::priority string?)
(spec/def ::has-context- (spec/keys :req [::context ::context-association-type ::context-association-name ::priority]))
(spec/def ::has-contexts (spec/coll-of ::has-context-))
(spec/def ::fact- (spec/keys :req [::global-id ::type ::name ::value]))
(spec/def ::facts (spec/coll-of ::fact-))
(spec/def ::attribute- (spec/keys :req [::name ::type ::value]))
(spec/def ::attributes (spec/coll-of ::attribute-))
(spec/def ::fulltext (spec/keys :req [::global-id ::text]))
(spec/def ::feature- (spec/keys :req [::global-id ::date ::location-meanings ::has-contexts ::facts ::attributes ::interaction-name]
                                :opt [::fulltext]))
(spec/def ::features (spec/coll-of ::feature-))
(spec/def ::attribute- (spec/keys :req [::name ::type ::value]))
(spec/def ::attributes (spec/coll-of ::attribute-))
(spec/def ::ioi-slice string?)
(spec/def ::ioi- (spec/keys :req [::global-id ::type ::datasource ::features ::attributes ::ioi-slice]))
(spec/def ::iois (spec/coll-of ::ioi-))
(spec/def ::data (spec/keys :req [::contexts ::datasources ::iois]))
(spec/def ::data- ::data)

但它无法生成以下样本：

(spec/fdef data->graph
  :args (spec/cat :data ::xml-spec/data-))

(println (stest/check `data->graph))

然后它将无法生成异常：Couldn't satisfy such-that predicate after 100 tries.

使用stest/check自动生成规范非常方便但是如何旁边的规格也有生成器？

Answer 1

当您从规范生成数据时看到错误Couldn't satisfy such-that predicate after 100 tries.，一个常见原因是s/and规范，因为spec仅根据第一个内部规范为s/and规范构建生成器。

这个规范似乎最有可能导致这种情况，因为s/and中的第一个内部规范/谓词是string?，而下面的谓词是正则表达式：

(s/def ::date (s/nilable (s/and string? #(re-matches #"^\d{4}-\d{2}-\d{2}$" %))))

如果您对string?生成器进行采样，您将看到它生成的内容不太可能与您的正则表达式匹配：

(gen/sample (s/gen string?))
=> ("" "" "X" "" "" "hT9" "7x97" "S" "9" "1Z")

test.check将尝试（默认为100次）以获得满足such-that条件的值，然后抛出您看到的异常（如果不是）。

生成日期

您可以通过多种方式为此规范实现自定义生成器。这是一个test.check生成器，它将创建ISO本地日期字符串：

(def gen-local-date-str
  (let [day-range (.range (ChronoField/EPOCH_DAY))
        day-min (.getMinimum day-range)
        day-max (.getMaximum day-range)]
    (gen/fmap #(str (LocalDate/ofEpochDay %))
              (gen/large-integer* {:min day-min :max day-max}))))

这种方法获得有效纪元日的范围，使用它来控制large-integer*发生器的范围，然后使用fmaps LocalDate/ofEpochDay生成的整数。

(def gen-local-date-str
  (gen/fmap #(-> (Instant/ofEpochMilli %)
                 (LocalDateTime/ofInstant ZoneOffset/UTC)
                 (.toLocalDate)
                 (str))
            gen/large-integer))

这从默认的large-integer生成器开始，并使用fmap提供一个函数，该函数从生成的整数创建java.time.Instant，将其转换为java.time.LocalDate，并将其转换为恰好与您的日期字符串格式匹配的字符串。 （这在Java 9及更高版本上使用java.time.LocalDate/ofInstant稍微简单。）

另一种方法可能使用test.chuck的regex-based string generator，或不同的日期类/格式化程序。请注意，我的两个示例都会生成在-9999 / + 9999之前/之后的年份，这与您的\d{4}年正则表达式不匹配，但生成器应该经常产生令人满意的值，这对于您的用例可能无关紧要。有很多方法可以生成日期值！

(gen/sample gen-local-date-str)
=>
("1969-12-31"
 "1970-01-01"
 "1970-01-01"
 ...)

将自定义生成器与规范一起使用

然后，您可以使用s/with-gen将此生成器与您的规范相关联：

(s/def ::date
  (s/nilable
   (s/with-gen
    (s/and string? #(re-matches #"^\d{4}-\d{2}-\d{2}$" %))
    (constantly gen-local-date-str))))

(gen/sample (s/gen ::date))
=>
("1969-12-31"
 nil ;; note that it also makes nils b/c it's wrapped in s/nilable
 "1970-01-01"
 ...)

如果您不想将自定义生成器直接绑定到规范定义，您还可以为采用覆盖映射的某些规范函数提供“独立”自定义生成器：

(gen/sample (s/gen ::data {::date (constantly gen-local-date-str)}))

使用此规范和生成器，我能够生成更大的::data规范，尽管由于某些收集规范，输出非常大。您还可以使用规范中的:gen-max选项控制生成期间的大小。