An example of unit tests for a currying function. One of the Casidoo challenges.

Currying_unit_tests_casidoo.js

// Currying (cool stuff)

function addg(a) {
    if (a === undefined) return a;
    return function g(b) {
        if (b !== undefined) {
            return addg(a+b);
        }
        return a;
    };
}

Unit test for addg:

console.assert(addg() === undefined, `addg() === ${addg()}, should be undefined`);
console.assert(typeof addg(1) === "function", `typeof addg(1) === ${typeof addg(1)}, should be function`);
console.assert(addg(1)(2)() === 3, `addg(1)(2)() === ${addg(1)(2)()}, should be 3`);