Writing Testable JavaScript

Writing Testable JavaScript Rebecca Murphey • Full Frontal 2012 ©
brianUphoto http://www.flickr.com/photos/snype451/5752753663/in/photostream/ Friday, November 9, 12

rmurphey.com • @rmurphey • bocoup.com Friday, November 9, 12

Writing Testable JavaScript Rebecca Murphey • Full Frontal 2012 ©
brianUphoto http://www.flickr.com/photos/snype451/5752753663/in/photostream/ Friday, November 9, 12

Friday, November 9, 12

you will design your code you will test your code
you will refactor your code other people will use your code there will be bugs facts of life Friday, November 9, 12

“do the pieces work together as expected?” integration tests Friday,
November 9, 12

def test_no_results fill_in('q', :with => 'foobarbazbimbop') find('.btn').click
assert( page.has_selector?('#results li.no-‐results'), 'No results is shown' ) assert( find('#results').has_content?('No results found'), 'No results message is shown' ) end selenium (via ruby) Friday, November 9, 12

“given input x, is the output y?” unit tests Friday,
November 9, 12

'#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { e.preventDefault(); if ( pending ) { return; } var form = $( this ); var query = $.trim( form.find( 'input[name="q"]' ).val() ); if ( !query ) { return; } pending = true; $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } }); $('<li>', { 'class' : 'pending', html : 'Searching …' }).appendTo( resultsList.empty() ); }); Friday, November 9, 12

anonymous functions, lack of structure complex, oversized functions lack of
con gurability hidden or shared state tightly coupled difficult to test Friday, November 9, 12

'#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { e.preventDefault(); if ( pending ) { return; } var form = $( this ); var query = $.trim( form.find( 'input[name="q"]' ).val() ); if ( !query ) { return; } pending = true; $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } }); $('<li>', { 'class' : 'pending', html : 'Searching …' }).appendTo( resultsList.empty() ); }); var resultsList = $( '#results' ); var liked = $( '#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { // ... }); Friday, November 9, 12

'#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { e.preventDefault(); if ( pending ) { return; } var form = $( this ); var query = $.trim( form.find( 'input[name="q"]' ).val() ); if ( !query ) { return; } pending = true; $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } }); $('<li>', { 'class' : 'pending', html : 'Searching …' }).appendTo( resultsList.empty() ); }); $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } }); Friday, November 9, 12

setup presentation & interaction application state data/server communication Friday,
November 9, 12

search data application state glue Friday, November 9, 12

use constructors to create instances support con gurability keep methods
simple don’t intermingle responsibilities guiding principles Friday, November 9, 12

test rst. Friday, November 9, 12

var liked = $( '#liked' ); var resultsList = $(
'#results' ); // ... resultsList.on( 'click', '.like', function(e) { e.preventDefault(); var name = $( this ).closest( 'li' ).find( 'h2' ).text(); liked.find( '.no-‐results' ).remove(); $( '<li>', { text: name } ).appendTo( liked ); }); Friday, November 9, 12

test('create a likes view', function() { var view =
new app.Views.Likes({ el: '#likes' }); ok( view ); }); Friday, November 9, 12

test('add a liked person', function() { var view =
new app.Views.Likes({ el: '#likes' }); view.add( 'Brendan Eich' ); ok( $('#likes').html().match('Brendan Eich') ); }); Friday, November 9, 12

app.Views.Likes = (function() { var Likes = function( settings
) { this.$el = $( settings.el ); }; Likes.prototype.add = function( name ) { this.$el.find( '.no-‐results' ).remove(); $( '<li>', { html : name } ).appendTo( this.$el ); }; return Likes; }()); Friday, November 9, 12

$.ajax( '/data/search.json', { data : { q: query },
dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html( tmpl({ people : data.results }) ); pending = false; } }); Friday, November 9, 12

test('adding search results', function() { var view = new
app.Views.SearchResults({ el: '#results' }); view.setData([ { name: 'Rebecca', company: { name: 'Bocoup' }, email: 'rebecca@ { name: 'Dan', company: { name: 'Bocoup' }, email: '[email protected] ]); var html = $( '#results' ).html(); ok( html.match( 'Rebecca' ) ); ok( html.match( 'Dan' ) ); equal( $( '#results li' ).length, 2 ); }); Friday, November 9, 12

app.Views.SearchResults = (function() { var SearchResults = function( settings
) { this.app = settings.app; this.$el = $( settings.el ); }; SearchResults.prototype.set = function( people ) { var $el = this.$el.empty(); return app.loadTemplate( 'people-‐detailed.tmpl' ) .done(function( t ) { $el.html( t( { people : people } ) ); }); }; return SearchResults; }()); Friday, November 9, 12

test('search data URL', function() { var search = new
app.Search(); var result = search.fetch( 'cat' ); equal( requests[0].url, '/data/search.json?q=cat' ); }); Friday, November 9, 12

module('search data', { setup : function() {
xhr = sinon.useFakeXMLHttpRequest(); requests = []; xhr.onCreate = function( req ) { requests.push( req ); }; }, teardown : function() { xhr.restore(); } }); Friday, November 9, 12

test('fetch returns a promise', function() { var search =
new app.Search(); var result = search.fetch( 'cat' ); ok( result.then ); }); Friday, November 9, 12

test('promise resolves with array', function() { var search =
new app.Search(); var result = search.fetch( 'cat' ); requests[0].respond( 200, { "Content-‐type" : "text/json" }, JSON.stringify( { results : [ 'cat' ] } ) ); result.done(function( data ) { equal( data[0], 'cat' ); }); }); Friday, November 9, 12

app.Search = (function() { var Search = function() {};
var processResults = function( resp ) { return resp.results; }; Search.prototype.fetch = function( query ) { return $.getJSON( '/data/search.json', { q : query }).pipe( processResults ); }; return Search; }()); Friday, November 9, 12

so. Friday, November 9, 12

where to start? Friday, November 9, 12

awesome tools grunt + qunit + phantomjs grunt-mocha grunt-jasmine sinon.js
chai.js Friday, November 9, 12

$ grunt init:gruntfile Friday, November 9, 12

/*global module:false*/ var child_process = require('child_process'); module.exports = function(grunt) {
// Project configuration. grunt.initConfig({ lint: { files: ['lib/**/*.js', 'test/**/*.js', '! test/lib/**/*.js', 'www/js/**/*.js'] }, qunit: { files: ['test/**/test-‐*.html'] }, watch: { files: [ '<config:lint.files>', 'www/templates/*.tmpl' ], tasks: 'test' }, jshint: { options: { curly: true, eqeqeq: true, immed: true, latedef: true, newcap: true, noarg: true, sub: true, undef: true, boss: true, eqnull: true, browser: true }, globals: { $ : true, _ : true, RSVP : true, app : true } }, uglify: {} }); grunt.registerTask('default', 'lint qunit'); }; Friday, November 9, 12

/*global module:false*/ var child_process = require('child_process'); module.exports = function(grunt) {
// Project configuration. grunt.initConfig({ lint: { files: ['lib/**/*.js', 'test/**/*.js', '! test/lib/**/*.js', 'www/js/**/*.js'] }, qunit: { files: ['test/**/test-‐*.html'] }, watch: { files: [ '<config:lint.files>', 'www/templates/*.tmpl' ], tasks: 'test' }, jshint: { options: { curly: true, eqeqeq: true, immed: true, latedef: true, newcap: true, noarg: true, sub: true, undef: true, boss: true, eqnull: true, browser: true }, globals: { $ : true, _ : true, RSVP : true, app : true } }, uglify: {} }); grunt.registerTask('default', 'lint qunit'); }; qunit: { files: ['test/**/test-‐*.html'] }, Friday, November 9, 12

pinboard.in/u:rmurphey/t:testable-‐javascript/ bit.ly/WL0R8U Friday, November 9, 12

rmurphey.com • @rmurphey • bocoup.com Friday, November 9, 12

Writing Testable JavaScript

Writing Testable JavaScript

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