reporter

If at any point you think of an experiment you'd like to try out, all of the code examples below are editable.

Every instance of Distilled you create can be passed a custom reporter function. This allows you to override Distilled's default test reporter, which controls how test results are logged and displayed.

var suite = new Distilled(function (test) {
    console.log('Callback is passed the finished test/suite as a parameter:', test === suite);
    console.log('`this` is set to the finished test/suite:', this === suite);
});

Child tests are resolved before parent tests. This allows you to bubble properties and failures up the test chain.

As an example, you could reverse the behavior of Distilled's built-in test reporter, which displays tests as passed even if they have a child test that failed. Because reporters know at display time whether or not child tests passed, this is a purely cosmetic choice.

var calls = [];
var suite = new Distilled(function (test) {
    calls.push(test.label);

    if (test === suite) {
        console.log('All tests/suites called in the correct order:', '_a-_b-a-b-A-B-' === calls.join('-'));
    }
});

suite.test('A').test('a').test('_a');
suite.test('B').test('b').test('_b');

When child tests resolve, a number of properties are attached to them that allow you to to display information about how the test ran.

var suite = new Distilled(function (test) {
    if (test === passed) {
        console.log('Labels set correctly for passed tests:', test.label === 'passed');
        console.log('`status` is set to `STATUS.PASSED`:', test.status === Distilled.STATUS.PASSED);
        console.log('there is no error:', test.error == null);
    }

    if (test === failed) {
        console.log('Labels set correctly for failed tests:', test.label === 'failed');
        console.log('`status is set to `STATUS.FAILED`:', test.status === Distilled.STATUS.FAILED);
        console.log('Error is set:', test.error === error);
    }
});

var passed = suite.test('passed', true);
var error = new Error('error');
var failed = suite.test('failed', Promise.reject(error));

One of Distilled's selling points is that children of failed tests will be ignored and not executed. If a test is already attached before a parent fails, then that test's status will be set to "skipped".

var suite = new Distilled(function (test) {
    if (test === a) {
        console.log('Status is set to `STATUS.SKIPPED`:', test.status === Distilled.STATUS.SKIPPED);
    }
});

var A = suite.test('A', false),
    a = A.test('a');

Remember from the very first code sample above that the test passed into the reporter function is literally the same test that you ran before. This means that if you want to attach additional properties, you can.

// Distilled can be extended just like any other class.
var ExtendedDistilled = function () {
    Distilled.apply(this, arguments);
};

// Distilled respects the constructor property when chaining
// and creating child tests.
ExtendedDistilled.prototype = Object.create(Distilled.prototype);
ExtendedDistilled.prototype.constructor = ExtendedDistilled;

//See the ``assert`` documentation for more info on what's happening here.
ExtendedDistilled.prototype.assert = function (assertion) {
    var that = this;
    var start = performance.now();

    return Distilled.prototype.assert.call(this, assertion)
        .then(function () {
            that.time = performance.now() - start;
        }, function (err) {
            that.time = performance.now() - start;
            return Promise.reject(err);
        });
};

var suite = new ExtendedDistilled(function (test) {
    if (test.label === 'timeout') {
        console.log('Test time was attached', test.time);
        console.log('Timeout test took <500 milliseconds to complete: ', test.time < 500);
    }
});

suite.test('timeout', new Promise(function (res) {
    setTimeout(function () { res(); }, 300);
}));