Any

A helper to saves lines of code in tests. Provides a number of objects with a custom equals method. Say, the any.core/uuid object equals to any UUID. The same approach for strings, numbers, and so on.

Table of Contents

• Demo
• Why?
• Installation
• Builtin objects
• Representation
• Equality, Equivalence, and Order
• Custom objects
• Other

Demo

(ns demo
  (:require
   [any.core :as any]))

;; positive cases

(= any/uuid (random-uuid)) ;; true
(= any/string "whatever")  ;; true
(= any/keyword :dunno)     ;; true

;; negative cases

(= any/uuid 1)          ;; false
(= any/string nil)      ;; false
(= any/symbol :keyword) ;; false

Custom equality works for nested items in maps, vectors and other collections:

(= {:id any/uuid :name "Ivan"}
   {:id (random-uuid) :name "Ivan"})

(= [any/uuid any/string]
   (list (random-uuid) "test"))

The library provides various objects for equality: Clojure primitives, Java classes from java.time.* and other packages, regex checking, ranges, and more (see below).

Why?

Moslty for tests, as it helps a lot. Imagine you're testing a function returning a map:

(deftest test-some-func
  (is (= {:this 1
          :that [:foo :bar]
          :more {:ok true}}
         (some-function 1 "abc" [:foo]))))

All fields are constant so there is nothing to worry about. A regular = operator works fine.

Should some-function return a map with a random UUID, you cannot blindly compare maps with =. At this moment, various solutions come into play. You may dissoc all random fiels and compare only the constant subpart:

(deftest test-some-func
  (is (= {:this 1
          :that [:foo :bar]
          :more {:ok true}}
         (-> (some-function 1 "abc" [:foo])
             (dissoc :id :created_at)))))

But you still need to ensure the result has both :id and :created_at though. That leads to clumsy code:

(deftest test-some-func
  (let [result (some-function 1 "abc" [:foo])]
    (is (= {:this 1
            :that [:foo :bar]
            :more {:ok true}}
           (dissoc result :id :created_at)))
    (is (uuid? (:id result)))
    (is (instance? java.time.Instance (:created_at result)))))

Any achieves the same in a shorter way:

(deftest test-some-func
  (is (= {:id any/uuid
          :created_at any/Instance
          :this 1
          :that [:foo :bar]
          :more {:ok true}}
         (some-function 1 "abc" [:foo]))))

This reminds Clojure Spec or Malli, yet partially. Schemas usually check types but not values. With Any, you obtain both: check values and when they're random or too complex, rollback to types.

Installation

Lein:

[com.github.igrishaev/any "0.1.0-SNAPSHOT"]

Deps.edn

com.github.igrishaev/any {:mvn/version "0.1.0-SNAPSHOT"}

Builtin objects

Clojure primitives:

• any/string
• any/uuid
• any/uuid-string (a string matching UUID pattern)
• any/int (short, integer, long)
• any/float (float, double)
• any/keyword
• any/symbol
• any/not-nil (like some?)

Parameter-depended objects:

Object	Comment
(any/instance SomeClass)	check if a value is an instance of SomeClass
(any/enum :foo :bar: :baz)	check if a value if one of the variadic arguments
(any/enum-seq [:foo :bar: :baz])	like enum but accepts a collection of items
(any/range 1 9)	if a given number is in range [1, 9)
(any/re-matches #"some regex")	if a value is a string matching the pattern
(any/re-find #some regex)	if a value is a string where the pattern can be found
(any/includes "substring")	check if a string includes a substring

Examples:

(= (any/range 1 9) 3)            ;; true
(= (any/range 1 9) 9)            ;; false
(= (any/enum 1 :foo 9 "test") 9) ;; true
(= (any/re-matches #"\s+foobar\s+") "  foobar  ") ;; true
(= (any/re-find #"\d+") "  foo42bar  ")           ;; true
(= (any/includes "foo") "aa foo bb")              ;; true

Java instances:

• any/LocalDate
• any/LocalDateTime
• any/LocalTime
• any/OffsetTime
• any/OffsetDateTime
• any/Instant
• any/ZonedDateTime
• any/Period
• any/File
• any/InputStream
• any/OutputStream
• any/Reader
• any/Writer
• any/Date
• any/UUID

Representation

Every Any object has a custom .toString and print-method implementations. This makes the output a bit clearer in tests:

(is (= {:id any/uuid :name "Ivan"}
       {:id 42 :name "Ivan"}))

FAIL in () (form-init4968882668721322291.clj:227)
expected: {:id <any UUID>, :name "Ivan"}
  actual: {:id 42, :name "Ivan"}

(is (= {:result {:data {:created_at any/Instant}}}
       {:result {:data {:created_at "bad string"}}}))

FAIL in () (form-init4968882668721322291.clj:235)
expected: {:result {:data {:created_at <any instance of java.time.Instant>}}}
  actual: {:result {:data {:created_at "bad string"}}}

Equality, Equivalence, and Order

Keep in mind that the standard = Clojure function relies on equivalence, not equality. Equivalence is a custom way to compare objects in Clojure. Say, instances of ArrayList and PersistentList are equivalent if they are of the same size and each Nth element is equivalent to its counterpart.

In Clojure, you cannot extend nor override equivalence as it's hardcoded in Java sources. The .equals method is a part of equivalence and is mostly used as the last resort. For this reason, Any doesn't provide objects for matching collections: it doesn't work.

When comparing Any objects with values, the order matters. Objects provided by Any should stay first:

;; like this
(= any/text "hello")

;; NOT like this
(= "hello" any/text)

These two forms expand into the following:

;; like this
(.equals any/text "hello")

;; NOT like this
(.equals "hello" any/text )

In the first case, the any/text object has got its own logic checking if the opposite object is a string. In the second case, the standard String.equals method is called.

Custom objects

Any objects are built with a number of utility macros, and you can reuse them. The any/instance accepts a class and returns an object which equals to instances of that class only:

(import 'com.acme.Class)

(def AnyClass
  (any/instance com.acme.Class))

(= AnyClass value)

The any macro accepts a binding symbol, a text representation and a custom body with the logic of equality:

(any/any [x "text for (.toString) or (print)"]
  (boolean (some-condition x)))

The body should always return true or false, but not nil. It's better to wrap the result with boolean to prevent such cases.

Links

The idea of making Any comes from this blog post: "A fake Clojure Object equals to what you want".

Other

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