assertions.md

clojure.test assertion extensions

\When running clojure.test based tests through Kaocha, some of the behavior is a little different. Kaocha tries to detect certain scenarios that are likely mistakes which make a test pass trivially, and turns them into errors so you can investigate and see what's up.

Kaocha will also render failures differently, and provides extra multimethods to influence how certain failures are presented.

Detecting missing assertions

• Given a file named "test/sample_test.clj" with:

(ns sample-test
  (:require [clojure.test :refer :all]))

(deftest my-test
  (= 4 5))

• When I run bin/kaocha

• Then the output should contain:

FAIL in sample-test/my-test (sample_test.clj:4)
Test ran without assertions. Did you forget an (is ...)?

Missing assertions are configurable

There are two ways to disable this detection:

• Add :kaocha/warnings {:zero-assertions :silent} into tests.edn.
• Add :kaocha/warnings {:zero-tests :error} into tests.edn.

Detecting single argument =

• Given a file named "test/sample_test.clj" with:

(ns sample-test
  (:require [clojure.test :refer :all]))

(deftest my-test
  (is (= 4) 5))

• When I run bin/kaocha

• Then the output should contain:

FAIL in sample-test/my-test (sample_test.clj:5)
Equality assertion expects 2 or more values to compare, but only 1 arguments given.
Expected:
  (= 4 arg2)
Actual:
  (= 4)
1 tests, 1 assertions, 1 failures.

Pretty printed diffs

• Given a file named "test/sample_test.clj" with:

(ns sample-test
  (:require [clojure.test :refer :all]))

(defn my-fn []
  {:xxx [1 2 3]
   :blue :red
   "hello" {:world :!}})

(deftest my-test
  (is (= {:xxx [1 3 4]
          "hello" {:world :?}}
         {:xxx [1 2 3]
          :blue :red
          "hello" {:world :!}})))

• When I run bin/kaocha

• Then the output should contain:

FAIL in sample-test/my-test (sample_test.clj:10)
Expected:
  {"hello" {:world :?}, :xxx [1 3 4]}
Actual:
  {"hello" {:world -:? +:!}, :xxx [1 +2 3 -4], +:blue :red}
1 tests, 1 assertions, 1 failures.