Using regular expressions in WatiN
Anyone that has done any serious test automation of ASP.NET applications knows that .NET is a tad verbose when it comes to the control names that it generates. ASP.NET generates its control ID’s based on a hierarchy of controls. For example, if you have a textbox inside a user control that is placed in side a placeholder, the of name property of the control will be something like name=”ctl00$ContentPlaceHolderMain$UserConrol1$txtLogin”. On some applications I test, I have seen control ID’s 130+ characters in length. This presents an interesting challenge to the automator where your scripts can easily become something like this:
There are two scenarios that we want to be able to easily handle to maximise script maintainability. Firstly, if the control is renamed, we only want to have to change the control in one place. Second, if the hierarchy of the controls is changed, (or if the control moves in the page) we want to be able to handle it easily.
One of the new features introduced into version 0.8 of WatiN is support for using regular expressions. This provides a extremely powerful way of solving both problems.
The first thing we will do is define a static class that returns the name property of the control. If this control was being used to test, say Amazon.com, I would structure the class that uses a namespace structure that allows the use of intellisense to help find controls at design time.
using System;
namespace Amazon
{
class LoginPage
{
public static string txtLogin = "ctl00$ContentPlaceHolderMain$UserConrol1$txtLogin";
}
}
This allows the test script to be simplified as follows:
Ok problem one solved, and now that we have our class, we can easily change it to use the regular expression support. If we want to ignore the whole control hierarchy and only match the control name txtLogin, then we can use an expression like:
[a-zA-Z0-9\$]*txtLogin
(If like me, you can never remember what the expression should be, I can highly recommend regexlib.com, which contains examples, reference sheets and a regex tester.) WatiN implements overloads in Find.ByName and can consume the control name as either a string or a Regex. This allows us to use the regular expressions by only changing how the control is defined in the class. An updated version of the class using regular expressions is as follows:
using System;
using System.Text.RegularExpressions;
namespace Amazon
{
class LoginPage
{
public static Regex txtLogin = new Regex("[a-zA-Z0-9\$]*txtLogin");
}
}
Now the only thing that will cause us problems is if the txtLogin control us renamed, or another txtLogin control is added to the page somewhere else. But what are the chances of that happening …