Principle 1

Context

Make clear what your unit is

Context

Case Studies

Typeahead

Intro.js

Traditional types of testing

Principle 2

Interface

Figure out how to access and observe the unit

Getting a unit

Getting a unit

var RubberDuck = function (name) {
    this._name = name;
    this.squawk = function () {...};
    this.swim = function () {...};
};

/* constructor */
var instance = new RubberDuck('Ducky');
                        

Getting a unit

var Utilities = {
    encodeUri = function (uri) {...};
    roundUp = function (number) {...};
    quote = function (string) {...};
};

/* global */
Utilities;
                        

Getting a unit

/* vivification */
jQuery('#my-awesome-list').carousel();

/* another example */
var myList = document.querySelector('#my-awesome-list');
Carousel.create(myList);
                        

Fixtures

Create test environment

• HTML structure
• Mocks, stubs
• Core libraries and CSS

Exercise

Get an instance of

• Bootstrap Carousel - jsbin.com/hicuri/1/edit
• Dijit Color Palette (programatically or declaratively) - jsbin.com/werew/3/edit

Hints

• getbootstrap.com/javascript/#carousel
• dojotoolkit.org/reference-guide/1.10/dijit/ColorPalette.html
• Replace "..." with valid image urls
• $('selector-for-carousel-root-element')
• registry.byId('id-of-palette-root-element')
• Inline script for dojoConfig is required in the HTML head, for declarative setup of color palette

Now that I have the unit, what can I do with it?

B/W Box Testing

• Black box: Don't care about internal implementation. Feed input and observe output.
• White box: Look at implementation of unit. Consider internal execution paths.

When white box testing is important

• Low-level software
• Critical software
• Dumb programmers

function add(number1, number2) {
    if (number1 === 90210) {
        return -1; // That is my lucky number! :) LOL FTW
    } else {
        return number1 + number2;
    }
}

Exercise

What can you do with instance? What can you observe?

var CountrySelector = function () {
    var default = 'Canada',
        submitButton = document.querySelector('#submit-country');

    var abbreviate = function (name) {
        return name.substring(0, 3);
    };

    this.countryLength = 2;
    this.getCountryCode = function (name) {
        return (name === 'Canada') ? 'CA' : null;
    };

    submitButton.addEventListener('click', function () {
        // make AJAX call to server
        submitButton.style.top = "0px"; // move box to top
        submitButton.style.color = "green"; // and turn it green
    });
};

var instance = new CountrySelector();

Answer

var CountrySelector = function () {
    var default = 'Canada',
        submitButton = document.querySelector('#submit-country');

    var abbreviate = function (name) {
        return name.substring(0, 3);
    };

    /*** Public properties and functions ***/
    this.countryLength = 2;
    this.getCountryCode = function (name) {
        return (name === 'Canada') ? 'CA' : null;
    };

    /*** Event handlers ***/
    submitButton.addEventListener('click', function () {
        /*** Effects ***/
        // make AJAX call to server
        submitButton.style.top = "0px"; // move box to top
        submitButton.style.color = "green"; // and turn it green
    });
};

var instance = new CountrySelector();
instance.countryLength; // 2
instance.getCountryCode('Canada'); // 'CA'
// clicking submit button makes a server call and moves the button

The Black Box

Interface

• Public functions
• Events
• Effects

Principle 3

Isolation

Eliminate or control external influences

What to control

Things that…

• make the test fail when the unit is correct
• we don't trust
• are unpredictable
• are time-sensitive
• have unwanted side-effects
• have states that are hard to trigger

What to control

• Databases and other persistent data sources
• User input and device output
• Networking
• Timers
• Dodgy code

Exercise

Identify the things that should be controlled for

Modernizr CSS prefixes

Typeahead Dropdown

Sinon Stubs

• Prevent real object/function from being used
• Force external dependencies to behave in a certain way

// Assume unit calls Dropdown.open()
// Override Dropdown.open() and do nothing when called
sinon.stub(Dropdown, 'open');

// Return false when called
sinon.stub(Dropdown, 'open').returns(false);

// Throw an exception when called
sinon.stub(Dropdown, 'open').throws();

Principle 4

Independence

Restrict interference between tests

Exercise

What's wrong here?

var hippo = new Hippo();

test('initalize makes hippo ready for action', function () {
    hippo.initalize();
    strictEqual(hippo.isReadyForAction(), true);
});

test('rest relaxes hippo', function () {
    hippo.rest();
    strictEqual(hippo.isRelaxed(), true);
});

test('yawn makes hippo sluggish', function () {
    hippo.yawn();
    strictEqual(hippo.isSluggish(), true);
});

Exercise

What's wrong here? (2)

var favouriteFoods = ['kale', 'poutine'];

test('eatOne removes a food item', function () {
    var hippo = new Hippo();
    hippo.eatOne(favouriteFoods);
    strictEqual(favouriteFoods.length, 1);
});

test('eatAll removes all food items', function () {
    var hippo = new Hippo();
    hippo.eatAll(favouriteFoods);
    strictEqual(favouriteFoods.length, 0);
});

Exercise

What's wrong here? (3)

test('draw appends a  on the specified element', function () {
    var hippo = new Hippo();

    hippo.draw(document.body);
    // look for img tag on document.body
    var imgElement = document.body.querySelectorAll('img');

    strictEqual(imgElement.length, 1);
});

Exercise

What's wrong here? (4)

test('dance creates shiny confetti and makes #fruity purple', function () {
    var hippo = new Hippo(),
        testElement = document.createElement('div');

    // arrange
    testElement.id  = 'fruity';
    document.body.appendChild(testElement);

    // act
    var result = hippo.dance();
    var pageColour = window.getComputedStyle(testElement)
        .getPropertyValue('color');
    document.body.removeChild(testElement);

    // assert
    strictEqual(result, 'confetti');
    strictEqual(pageColour, 'purple');
});

Independence

Tests should…

• Run in any order
• Run in parallel
• Run repeatedly with same results (indempotence)
• Not make permanent global changes
• Test one thing at a time

Principle 5

Adequacy

Create practical test cases

Test Strategies

Subject Selection

• Test all interface functions, events, etc
• Do not test external dependencies
• Do not test underlying framework
• Do not test preconditions (e.g. null checks)

Test Strategies

Case Selection

• Typical
• Extreme
• Maximum variation
• High business risk
• Failure

QUnit Cheat Sheet

module('hippoTestSuite', {
    setup: function () { // common setup actions... },
    teardown: function () { // common teardown actions... }
});

test('Description of test', function () {
    // arrange
    // act
    // assert
    strictEqual(expected, actualResult, 'optional error message');
});

test('Description of another test', function () {
    // arrange, act, assert
    strictEqual(expected, actualResult, 'optional error message');
});

Exercise

Write test cases for at least one of these

• _.isArray(object)
• jQuery.empty()
• d3.histogram()(values)
• moment.duration().humanize()

QUnit template - jsbin.com/xomiwi/1/edit

Test Strategies

Basis path testing

var humanizeDates = function (date1, date2) {
    if (date1 < date2) {
        if (date2 - date1 > 500) {
            return 'very long time ago';
        }
        return 'long time ago';

    } else if (date1 > date2) {
        if (date1 - date2 > 500) {
            return 'very far in future';
        }
        return 'in future';
    }
    return 'same time';
};

Statement coverage = % statements executed in tests

Test Strategies

Basis path testing

Test Strategies

Boundary Value Analysis

Equivalent partition = range of values that should give the same result

Boundary value = value that separates adjacent equivalent partitions

Test Strategies

Boundary Value Analysis

moment(someDate).isAfter(anotherDate)

        eq partition 1             eq partition 2
|--------------------------|---------------------------|
0                         now                       max Date

Testing Events

test('bump causes hippo to trigger a burp event', function () {
    var burpSpy = sinon.spy();
    
    // arrange
    var hippo = new Hippo();
    $('body').on('burp', burpSpy);
    
    // act
    hippo.bump();
    
    // assert
    strictEqual(burpSpy.calledOnce, true);
});

Exercises

• Verify custom width option works for YUI Slider - jsbin.com/mizaq/1/edit
• Verify a change event is triggered when jQuery.progressbar() changes value - jsbin.com/xomiwi/2/edit
• Verify that nativeTemplateEngine.renderTemplateSource() from knockout.js calls ko.utils.parseHtmlFragment() on IE<9 - jsbin.com/siyas/1/edit

Principle 6

Clarity

Create understandable tests

Unclear structure

test('computeCommonFactor returns -1', function () {
    var l = new Factor(),
        div = document.createElement('div');
    sinon.stub(someMathLib, 'factorize').returns(2);
    div.id = 'factor';
    l.init(div);
    strictEqual(l.computeCommonFactor(-123), -1);
    l.destroy();
    someMathLib.factorize.restore();
});

Clear structure

test('computeCommonFactor returns -1 when an invalid argument is given', function () {
    var factor = new Factor(),
        fixture = document.createElement('div'),
        invalidArgument = -123,
        result;
    
    // arrange    
    sinon.stub(someMathLib, 'factorize').returns(2);
    fixture.id = 'factor';
    factor.init(fixture);
    
    // act
    result = factor.computeCommonFactor(invalidArgument);
    factor.destroy();
    someMathLib.factorize.restore();
    
    // assert
    strictEqual(result, -1);
});

Clear structure

• Subject, condition, expected result (for test names)
• Arrange, act, assert (for statements)
• Test one thing at a time

Low readability

test('hide fires a hidden event', function () {
    var accordionElement = document.createElement('ul'),
        accordionTab1 = document.createElement('li'),
        accordionTab2 = document.createElement('li'),
        listener = sinon.spy();
    
    // arrange    
    sinon.stub(someLib, 'accordify', function (options) {
        if (options.foo === true) {
            return {
                goo: function () { return true; },
                hoo: function () { return ''; }
            };
        }
        return {
            goo: function () {},
            hoo: function () {}
        };
    });
    accordionElement.classList.add('myAccordion');
    accordionTab1.classList.add('tab');
    accordionTab2.classList.add('tab');
    accordionElement.appendChild(accordionTab1);
    accordionElement.appendChild(accordionTab2);
    qunitFixture.appendChild(accordionElement);
    accordion = jQuery('.myAccordion').accordion(); // init
    jQuery.on('hidden', listener);
    
    // act
    accordion.hide();
    
    // assert
    ok(listener.calledOnce);
    
    // cleanup
    jQuery.off('hidden', listener);
    accordion.destroy();
    someLib.accordify.restore();
});

High readability

var standardAccordion;
module('accordion', {
    setup: function () {
        setupAccordifyStub();
        standardAccordion = createAccordion();
    },
    teardown: function () {
        standardAccordion.destroy();
        someLib.accordify.restore();
    }
});

test('hide fires a hidden event', function () {
    var hiddenEventListener = sinon.spy();

    // arrange
    jQuery.on('hidden', hiddenEventListener);

    // act
    standardAccordion.hide();

    // assert
    ok(hiddenEventListener.calledOnce);

    // cleanup
    jQuery.off('hidden', hiddenEventListener);
});

Better readability

• Less boilerplate
• Meaningful mock names
• No obsolete tests

Exercise

Critique unit test for jQuery UI accordion - https://github.com/jquery/jquery-ui/blob/master/tests/unit/accordion/accordion_events.js

Principle 7

スピード！スピード！スピード！

( Speed! )

Reduce barriers to working with tests

Fast and painless

• Avoid polling and delays
• Make test suites easy to run
• Fail fast and clear