Thursday, July 11, 2013

testing YUI apps with phantomjs

It turns out that wiring up phantomjs to process a web page that runs a test suite based on yui's test module is pretty easy to do. I wish I did this sooner. Here's what I got working.

First, I'm already in the habit of setting up pages like this that run a javascript module through some tests. I just use yui's test framework, since I use yui for everything else, and yui test works basically the same way as junit - which I use when coding java. I wind up with the following code (on github here):

    littleware.littleYUI.bootstrap().use( 
 'littleware-littleUtil', 'test',
 function (Y) {
     // The modules are loaded and ready to use.
     // Your code goes here!
     var util = Y.littleware.littleUtil;
     var log = new util.Logger( "littleUtilTestSuite.html" );
     var suite = util.buildTestSuite();
     
     Y.Test.Runner.add( suite );
     
     if ( typeof( window.callPhantom ) != 'undefined' ) {
  // phantomjs environment!
  console.log( "Phantomjs detected!" );
  Y.Test.Runner.subscribe( Y.Test.Runner.COMPLETE_EVENT, window.callPhantom );
     }

     Y.Test.Runner.run();          
    });

The thing to notice is the window.callPhantom feature detection. Phantomjs integrates the V8 javascript engine with Webkit's DOM magic in a cool command-line javascript console. There's probably a better way to say that, but the important thing for me is that phantomjs offers a great way to run and evaluate the results of test web pages from the command line.

The phantomjs web site has a great list of references on its "headless testing" page, and I think my setup is pretty similar to what others do. My setup takes advantage of one trick that I wanted to mention - listening for YUI's test-run complete event with phantomjs' webpage.onCallback function to pass the web-page test results through to the phantomjs script (below) that runs through a series of test web pages. Ugh - that may not make much sense, but hopefully the "phantomTestRunner.js" script below (and in github) helps clarify what I mean.

/**
 * Little phantomjs script that opens a list of urls given
 * in the first argument as a comma-separated list.
 * Intended for running YUI test suites that callback to
 * phantom at test completion via:
 *    
 *    <pre>
 *       if ( typeof( window.callPhantom ) != 'undefined' ) {
 *           // phantomjs environment!
 *           console.log( "Phantomjs detected!" );
 *           Y.Test.Runner.subscribe( Y.Test.Runner.COMPLETE_EVENT, window.callPhantom );
 *       }
 *
 *    </pre>
 */

var system = require( 'system' );

if ( (system.args.length < 2) || system.args[1].match( /^-+/ ) ) {
    // use comma-separated list - easier to integrate with ant that way
    console.log( "script takes exactly one argument: a comma-separated list of test urls" );
    phantom.exit(1);
}

var urlList = system.args[1].split( /,+/ );
/*
for ( var i = 1; i < system.args.length; ++i ) {
    urlList.push( system.args[i] );
}
*/

var resultList = [];
var currentTest = 0;

var page = require( 'webpage' ).create();
page.onConsoleMessage = function(msg) { console.log( msg ); };

function runTest( url ) {
  page.open( url,
     function( status ) { 
         console.log( url + " status: " + status ); 
         if ( status != "success" ) {
             phantom.exit(1);
         } 
         page.evaluate( function() { console.log( "page location: " + window.location.href ); } );
     }
 );    
}

page.onCallback = function( testResult ) {
    resultList.push( testResult );
    currentTest += 1;
    if ( currentTest < urlList.length ) {
        runTest( urlList[currentTest] );
    } else {
        console.log( "-------------------------------------------------------------" );
        console.log( "-------------------------------------------------------------" );
        console.log( resultList.length + " Tests complete: " );
        console.log( JSON.stringify( resultList ) );
        phantom.exit( 0 );
    }
};


runTest( urlList[0] );

Anyway, long story short, running something like:
phantomjs phantomTestRunner.js http://apps.frickjack.com/littleware_apps/testsuite/littleUtilTestSuite.html
prints out the web-console messages from the page's test suite (the script can run multiple pages), and collects all the results at the end (I need to do more work with that). Pretty cool!

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