Protractor/jasmine toHaveClass custom matcher

toHaveClass.js

/**
 * Custom "toHaveClass" matcher.
 *
 * Based on https://gist.github.com/darthwade/9305669
 * and https://gist.github.com/elgalu/94284ec0ac3e8a590507
 *
 * usage :
 *   require('./toHaveClass.js');
 *   ...
 *   expect($('html')).toHaveClass('wf-active');
 *   expect($('#button')).not.toHaveClass('disabled');
 */

/* global beforeEach, protractor */

beforeEach(function() {
    this.addMatchers({
        toHaveClass: function (expected) {
            var deferred = protractor.promise.defer();
            this.actual.getAttribute('class').then(function(classes) {
                var hasClass = classes.split(' ').indexOf(expected) >= 0;
                deferred.fulfill(hasClass);
            });
            return deferred.promise;
        }
    });
});