Unit Testing

Clojure includes the clojure.test library that helps you write code that checks your code works correctly.

It provides ways to name and group tests, make assertions, report results, and orchestrate test suites.

A clojure.test example

We are writing a functional called capitalize-map-values which capitalizes the values in a map (assuming they are strings).

To test this function, define a test using clojure.test/deftest

;; A function in namespace com.example.core
(defn capitalize-map-values
  "Returns a new map with values for keys 'ks' in the map 'm' capitalized."
  [m & ks]
  (reduce (fn [m k] (update-in m [k] clojure.string/capitalize)) m ks))

;; The corresponding test in namespace com.example.core-test
(require '[clojure.test :refer :all])

;; In a real test namespace, you would also :refer all of the target namespace
;; (require '[com.example.core :refer :all])

(deftest test-capitalize-entries
  (let [employee {:last-name "smith"
                  :job-title "engineer"
                  :level 5
                  :office "seattle"}]
    ;; Passes
    (is (= (capitalize-entries employee :job-title :last-name)
           {:job-title "Engineer"
            :last-name "Smith"
            :office "seattle"
            :level 5}))
    ;; Fails
    (is (= (capitalize-entries employee :office)

Run the test with the +clojure.test/run-tests+ function:

;; -> {:type :summary, :pass 1, :test 1, :error 0, :fail 1}
;; *out*
;; Testing user
;; FAIL in (test-capitalize-entries) (NO_SOURCE_FILE:13)
;; expected: (= (capitalize-entries employee :office) {})
;;   actual: (not (= {:last-name "smith", :office "Seattle",
;;                    :level 5, :job-title "engineer"} {}))
;; Ran 1 tests containing 2 assertions.
;; 1 failures, 0 errors.

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