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Automatic spec test check generation

Kaocha can discover all of your fdefs and generate clojure.spec.test.check tests for them. This saves you the trouble of writing your own boilerplate, and gives you the truly "free" generative testing that clojure.spec promises.

There are two ways you can use this feature:

  1. Adding :kaocha.type/spec.test.check test suites to your tests.edn:
  • :kaocha.testable/type = :kaocha.type/spec.test.check
  • :kaocha/source-paths: Normally your fdefs are with your code, so this can probably be left defaulted at ["src"]
  • :kaocha.spec.test.check/checks: Optional. If you want to orchestrate multiple "sets" of checks with differing parameters, you can specify them here. This is a collection of checks, each check being a map which may contain the following optional keys:
  • :kaocha.spec.test.check/syms: Currently your only options are either :all-fdefs (default) or to provide a set of the symbols for the fdefs which you want to test. Eventually we will add :other-fdefs to select all the fdefs that were not specifically mentioned in other checks.
  • :clojure.spec.test.check/instrument? Turn on orchestra instrumentation during fdef checks
  • :clojure.spec.test.check/check-asserts? Run s/check-asserts during fdef checks
  • :clojure.spec.test.check/opts: A map containing any of:
  • :num-tests: Test iterations per fdef
  • :max-size: Maximum length of generated collections
  • All of the keys within each check can also be given in the top-level test suite map to be merged by default into all checks.
  1. The kaocha.plugin.alpha/spec-test-check plugin
  • This provides a sane default test suite for automatically checking all of your fdefs. Spec test checking can be configured with more granularity in tests.edn (as above), but the plugin exists for easy and simplistic CLI control.
  • Regardless of whether you add the test suite(s) to tests.edn yourself, you can also use this plugin to forceably override certain test parameters:
  • --[no-]stc-instrumentation = :clojure.spec.test.check/instrument?
  • --[no-]stc-asserts = :clojure.spec.test.check/check-asserts?
  • --stc-num-tests NUM = :num-tests
  • --stc-max-size SIZE = :max-size
  • By default, this plugin also adds :no-gen to :kaocha.filter/skip-meta. You might want to decorate an fdef-ed function with ^:no-gen if there is either no good generator for one or more of its arguments or if the function is side-effectful.

Detects and checks fdefs using tests.edn

  • Given a file named "tests.edn" with:
{:tests [{:type :kaocha.type/spec.test.check
          :id   :generative-fdef-checks}]}
  • Given a file named "src/sample.clj" with:
(ns sample
  (:require [orchestra.core :refer [defn-spec]]))

(defn-spec ok-fn  boolean? [x int?] true)
(defn-spec bad-fn boolean? [x int?] x)
  • When I run bin/kaocha --reporter --no-randomize --no-color

  • Then the output should contain:

--- generative-fdef-checks (clojure.spec.test.check) ---------------------------
  sample/bad-fn FAIL

FAIL in sample/bad-fn (sample.clj:5)
== Checked sample/bad-fn ====================

-- Function spec failed -----------

  (sample/bad-fn 0)

returned an invalid value.


should satisfy


Detected 1 error

expected: boolean?
  actual: 0
2 tests, 2 assertions, 1 failures.

Plugin: kaocha.plugin.alpha/spec-test-check

  • Given a file named "src/sample.clj" with:
(ns sample
  (:require [orchestra.core :refer [defn-spec]]))

(defn-spec ok-fn  keyword? [k keyword?] k)
(defn-spec bad-fn boolean? [k keyword?] (ok-fn k))
  • When I run bin/kaocha --reporter --no-randomize --no-color --plugin kaocha.plugin.alpha/spec-test-check

  • Then the output should contain:

  sample/bad-fn FAIL

Can you improve this documentation? These fine people already did:
Arne Brasseur, Rob Hanlon & Imre Kószó
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