A micro-library to perform basics unit tests without installing a complete library

unit-test.js

var UnitTest = (new (function() {

    var testOutput;

    this.load = function(name) {
        var req, testI, _test = true;

        req = new XMLHttpRequest();
		req.open('GET', name, false);
		req.send(null);

        if(req.status !== 200) {
            throw new Error('Failed to load unit test : request failed');
            return false;
        }

        if(!testOutput) {
            testOutput = document.createElement('div');
            testOutput.setAttribute('id', 'tests-output');
            testOutput.style.border  = '1px solid gray';
            testOutput.style.padding = '5px';
            document.body.appendChild(testOutput);
        } else
            testOutput.innerHTML = '';

        function describe(name, callback) {
            var dom;

            if(!_test)
                return ;

            if((dom = document.getElementsByClassName('describe')).length)
                dom[dom.length - 1].style.color = 'green';

            UnitTest.output('<pre style="font-size:20px;margin:0;padding:0;" class="describe">' + name + '</pre><br />');
            testI = 0;
            var durey, started = Date.now();
            callback();
            durey = Date.now() - started;

            if(_test) {
                dom = document.getElementsByClassName('describe');
                dom[dom.length - 1].style.color = 'green';
                dom[dom.length - 1].innerHTML  += ' <small>' + durey + ' ms</small>';
            }
        }

        function it(name, callback) {
            if(!_test)
                return ;

            testI  += 1;
            var msg = '&nbsp;&nbsp;&nbsp;&nbsp;' + testI + ') ' + name, started = Date.now();

            try { callback(); }
            catch(e) {
                UnitTest.output('<pre style="color:red;margin:0;padding:0;" class="log log-failed">' + msg + ' (' + (Date.now() - started) + ' ms)</pre>');
                UnitTest.failed(e.stack);
                _test = false;
                return ;
            }

            UnitTest.output('<pre style="color:green;margin:0;padding:0;" class="log">' + msg + ' (' + (Date.now() - started) + ' ms)</pre>');
        }

        function assert(val1, val2, message, nonStrict) {
            if(nonStrict ? val1 != val2 : val1 !== val2)
                throw new Error('<em>' + (message || 'No description') + '</em>\nAssertion failed. Expected "' + val2 + '", but "' + val1 + '" gived');
        }

        var durey, started = Date.now();

        try { (new Function(['describe', 'it', 'assert'], req.responseText)).apply(window, [describe, it, assert]); }
        catch(e) { _test = false; this.failed('Test failed : Runtime error\n' + e.stack); }

        durey = Date.now() - started;

        if(_test)
            testOutput.innerHTML += '<br /><pre style="color:green;margin:0;padding:0;" class="success">Test succeed in ' + durey + ' ms !</pre>'
    };

    this.output = function(content) {
        testOutput.innerHTML += content;
    };

    this.failed = function(stack) {
        var dom = document.getElementsByClassName('describe');

        if(dom.length)
            dom[dom.length - 1].style.color = 'red';

        testOutput.innerHTML += '<br /><pre style="color:red;margin:0;padding:0;" class="failed">' + stack + '</pre>';
    };

})())

// Example of using :
UnitTest.load('tests/math.js');

// FILE : tests/math.js

var num = NaN;

while(Number.isNaN(num))
    num = parseInt(prompt('Choose a number', '-5'));

describe('Test some maths operations', function() {
    it('test basic maths', function() {
        assert(1 + 1, 2, 'WTF ???');
        assert(2 * 2, 4, 'WTF ???');
        assert(0 * 2, 0, 'WTF ???');
    });

    it('test some functions', function() {
        assert(Math.floor(2.3), 2, 'Math.floor doesn\'t seem to work properly');
        assert(Math.pow(2, 2), 4, '2^2 != 4');
        assert(Math.pow(2, 4), 16, '2^4 != 16');
    });

    it('test some things', function() {
        assert(Math.abs(num), num < 0 ? -num : num, 'Math.abs | absolute function doesn\'t work properly');
    });
});

// ENJOY !