Test Automation Blog

Actually for the last two days there were two new releases of Selenium - 1.0.2 and 1.0.3 (released on the next day following 1.0.2 to fix some issues). The most important feature in the new release for me is Firefox 3.6 support. If you are a Mac fan you will be glad to know that OS X Snow Leopard is now supported too.

When it comes to  tools I use for work I usually prefer to wait a little before upgrading, so that any potential problems that might be there are discovered by other people and not by me (the quick release of 1.0.3 seems to confirm that this is actually a good idea). On the other hand my previous experience with upgrading test automation tools shows that I sometimes run into problems no one else has found.

So this time I decided to upgrade to 1.0.3 early and I will blog about my experience.

By the way, there is also a new official Selenium blog.

XPather is a small Firefox extension, which I find indispensable (together with Firebug) when writing Selenium tests.

It adds a 'Show in Xpather...' item to the context menu for all the UI elements on the web page. When selected this option opens a small 'XPather Browser' window showing a very, very long XPath expression which selects the element you chose.

Like /html/body/table[2]/tbody/tr[2]/td[2]/div[@id='login']/form[@id='gaia_loginform']/div[@id='gaia_loginbox']/table/tbody/tr/td/div/table[@id='gaia_table']/tbody/tr[8]/td[2]/input, which is the expression you get when you select the 'Sign in' button on the login page of Gmail. Of course you can write your own expressions and test to see what is selected on  the page.  So you can opt to use for example //input[@name='signIn'], which is much shorter and better way to locate the same button. I use XPather mostly to interactively test complex expressions whenever I am trying to locate some hard-to-find object on the web page.

Several months ago I started working on a new test automation project for a web site and one of the first things to do was to evaluate and choose a tool for the task. The two main contenders were Selenium and IBM Rational Functional Tester. I chose Selenium and since then never got to regret this choice. Here are some of the main reasons I lke this opensource tool much better than the expensive commerial alternatives for web automation:

Selenium acknowledges the fact that to create useful tests you will have to code them

Yes, it gives you a tool that can record sequences of user interactions, but as a whole Selenium is not built with the assumption that this will be the main approach you will use to create your tests. The recording tool (which is a very easy to install Firefox plugin) is useful as a learning aid and maybe for very simple tests. But what I like most about it is that it can covert your recorded sequence to code in any of the supported scripting languages.  And this brings me to the second point:

You get to choose the scripting language

Most commercial automation tools force you to use some Visual Basic dialect as a scripting language. If you are lucky you get something relatively functional like VBA (with TestPartner) or even VB.NET (with Rational Functional Tester). Otherwise you might be forced to code your tests in VBScript, which is really, really painful (the main reason why I don't like QuickTest Professional). Rational Functional Tester also lets you use Java, which makes it my favorite among the commercial tools.

Selenium is language-agnostic. You can use almost any programming language you want. C# and Java are popular and PHP is also an option if you are automating a PHP web app and want to stick to the same language for testing. Ruby is a great language that makes coding fun and the Selenium library for Ruby provides some domain-specific idioms for testing, similar to what Rails does for web development. If you are a Perl, Python or Groovy fan you can use them too. As an additional bonus you will be able to use any development environment you are comfortable with to write your scripts – be it Eclipse, Microsoft Visual Studio or even Vi or Emacs if you want to.

Selenium has a powerful approach for locating UI objects

Most automation tools are surprisingly limited in the way they identify the UI objects to interact with. They let you locate a control by some unique property (like id) or by a collection of properties which together identify it uniquely on the web page. In my experience this approach is sufficient in only about half of the real-world cases.

Imagine a web page containing 3 identical OK buttons. The buttons are exactly the same and have no id's or anything in their properties to distinguish them. Lets say that the first button is located in a form with id 'signup', the second is inside 'order' and the third is inside 'invoice'. Most automation tools do not let you easily identify a UI object in relation to other objects in the page, i.e. you can not say I want to click the button with caption 'OK', which is located inside the 'signup' form. Normally the most you get is I want to click the second button with caption 'OK' on the page. This will work, but only until you get a new version of your application with added additional OK button above the one you are interested in. The XPath expressions in Selenium can locate objects in the DOM document hierarchy (“//form[@id='signup']//input[@type='button' and @value='OK']”) and are very powerful – for instance you can specify that you want to click the checkbox, which is located inside a table row next to a cell with some specific text in it.

Your tests will run on any browser without changes (well, almost)

While you should not expect that automated tests will catch most browser-dependent bugs (like broken layout), the option to run your tests on all browsers that you support is definitely useful. As with programming languages, Selenium offers you a wide choice of browers to run your tests on – not only specific versions of IE and maybe Firefox (the choice you are likely to get from commercial test automation tools), but also Safari, Chrome and Opera. What is more important – about 95% of your tests will run without any changes on all supported browsers. I don't know other automation tool that does this.

It is surprisingly stable and robust for a 1.0 version

My experience with test automation is that if you want to run lots of long tests, you have to expect that something will go wrong at some point – random crashes are not that uncommon in this business. Selenium is at least as stable as anything else I have tried and we routinely run hour-long tests without any problems.

If the application you are testing tends to open new browser windows using the target="_blank" technique, you might have some problems with Selenium.

One of the reasons I find Selenium a great test automation tool for the web  is that it lets you easily run your test scripts on different browsers without too much effort. Most scripts will run smoothly on IE, Firefox and even on more exotic browsers like Safari, Opera and Chrome without needing browser-specific code or having to tweak the test for a particular browser.  One of the few areas where you are likely to face problems is the handling of pop-up windows.  If the application you are testing tends to open new browser windows using the target="_blank" technique, you might have some problems with Selenium. The standard .selectWindow() method provided by Selenium requires either a title of the pop-up window (which is often the same as the title of the main window) or a name or a variable name (which are both missing, when the window is opened using a target="_blank" link).

You will need a workaround to select such windows and unfortunately the workarounds do not always work the same for all browsers. The following code snippets might be useful if you run into the same problem. They are tested on the *chrome and *iehta Selenium modes (with Internet Explorer 7 and Firefox 3).

Here is how you can select the pop-up window which is opened after a target="_blank" link is clicked. This actually combines several hacks and workarounds, but works at the end (at least for me):

        //A hack to select unnamed pop-up windows
        if (browser.equals("*iehta")){
            //Find out if Selenium substituted the blank target...
            if (selenium.isElementPresent(
                       "//a[starts-with(@target,'selenium_blank')]")) {
                // ...and make it notice the new window on IE
                selenium.openWindow("", selenium.getAttribute(
                      "//a[starts-with(@target,'selenium_blank')]@target"));
            }
        }
        String [] winNames = selenium.getAllWindowNames();
        //the last one is the pop-up window we want
        selenium.waitForPopUp(winNames[winNames.length-1], timeout);
        selenium.selectWindow(winNames[winNames.length-1]);

And here is how you can go back to the main window after you finished working with the pop-up:

        String [] winTitles = selenium.getAllWindowTitles();
        selenium.selectWindow(winTitles[0]);

Opensource might actually be better.

In case you are in the process of evaluating test tools, this review by Forrester research might give you a good initial overview of the current commercial offerings - The Forrester Wave™: Functional Testing Solutions, Q3 2008

It looks at solutions that support the whole testing and quality management process and the conclusion is not surprising:

"In today's market, HP is the default choice"

I find the whole thing objective and if you read it carefully you will be able to find the key facts about the automation tools.
The evaluated vendors and the corresponding tools are HP (ex Mercury) with QuickTest Professional, IBM (ex Rational) with Rational Functional Tester, Compuware with TestPartner, Borland (ex Segue) with SilkTest plus also tools from Empirix and Seapine.

The review has its main emphasis on test management and not on test automation:

"Testing teams looking to purchase just a single product should focus on test management first, since mature practices in this area are a prerequisite for success with test automation."

While this sounds logical at first, I somehow can not agree with it entirely. But what follows is really interesting:

"There are exceptions, though: most notably, development teams looking to automate their own regression testing. Commercial test automation tools, however, tend to be less effective here than open source alternatives like FIT/FitNesse or Selenium."

and:

"Both open source testing tools and SOA testing tools are relatively small parts of the functional testing tools market, but they’re growing in importance. Why? Because iterative development methodologies demand that test automation start earlier in the life cycle, and the testing organizations that purchase commercial tools struggle to make this a reality."

It seems that the analysts that wrote this really have some insignt in the business. Overall it is a very interesting read. Did you know that the element Selenium is the antidote to Mercury poisoning?