Infix Operators for Test Assertions

When you are writing tests, it's common to want to check a number of properties against a given value.

(require '[clojure.test :refer :all]
         '[schema.core :as s])

(deftest my-test
  (let [response ...]
    (is (= (:status response) 200))
    (is (= (count (get-in response [:headers "content-length"])) (count "Hello World!")))
    (is (= (count (get-in response [:headers "content-type"])) "text/plain;charset=utf-8"))
    (is (nil? (s/check s/Str (get-in response [:headers "content-type"]))))
    (is (instance? java.nio.ByteBuffer response))
    ))

This can get a bit cumbersome.

iota is a micro-library that provides a single macro, juxt.iota/given, that allows you to create triples, each of which expands into a clojure.test/is assertion.

(require '[clojure.test :refer :all]
         '[schema.core :as s]
         '[juxt.iota :refer [given]])

(deftest my-test
  (given response
          :status := 200
          :headers :⊃ {"content-length" (count "Hello World!")
                       "content-type" "text/plain;charset=utf-8"}
          [:headers "content-type"] :- s/Str
          :body :instanceof java.nio.ByteBuffer))

It's a little less typing, which might give you the extra time to add more checks, improving your testing.

In each of these cases v represents the given value.

The left hand operand of your expressions can be a vector, which acts as a path. A bit like -> but you can also use strings and numbers as well as keywords and functions. A (contrived) example:

(deftest contrived-test
  (given {:a {"b" '({} {} {:x 1})}}
    [:a "b" 2] := {:x 1}
    [:a "b" count] := 3))

Add the following dependency to your project.clj file

[juxt/iota "0.2.3"]

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