Assert-testing

This repository contains essentially just two files. A Java file

package testing;

public class Util {

    public static void different(int a, int b) {
        assert(a != b);
    }

}

and a Clojure file

(ns main
  (:import testing.Util)
  (:gen-class))

(defn different [a b]
  (assert (not= a b)))

(defn -main [& args]
  (let [a (parse-long (nth args 1))
        b (parse-long (nth args 2))]
    (case (first args)
      "java" (Util/different a b)
      "clj" (different a b)
      (throw (UnsupportedOperationException.)))))

the only goal is to check when which assertion is enabled.

At the REPL

Assuming we execute the following commands in the main namespace above without any further tweaks.

(Util/different 1 1)

passes without any complains (Java assertions are disabled by default) where as

(different 1 1)

results in java.lang.AssertionError. If we pass the java option -ea (or -enableassertions) as :jvm-opts when starting the REPL both of the above result in an assertion error.

With (set! *assert* true/false) you can enable/disable assertions in Clojure. Beware that you need to recompile your functions (in this case different) for this to have an effect.

Jars

Let's compile an uberjar

clj -T:build uber

Excecuting

java -jar target/assert-testing-0.1.2-standalone.jar java 1 1

still results in no assertion getting thrown. As previously Java assertions are disabled by default. You can enable them by passing -ea to the java command.

java -jar target/assert-testing-0.1.2-standalone.jar clj 1 1

The above on the contrary throws. To disable Clojure assertions you need to compile your Clojure files with something like

(with-bindings {#'clojure.core/*assert* false}
    compile-your-stuff
    )

or use something like clojure.tools.build.api/compile-clj with the same bindings.

FiV0/assert-testing

Assert-testing

At the REPL

Jars