The final part of this series on web application automation will focus on some examples using the concepts discussed in the previous two parts. We shall also discuss some of the limitations of using the DOM and the alternatives available to automate web application testing.
Automating a Web Page
The basic automation of web pages is simple and requires only the combination of the concepts discussed in the first two parts of this series. Before looking in more detail at the examples of automation we need to take into consideration the following DOM limitations mean that not all web pages can be easily automated.
Only HTML/DHTML web content can be automated. Web applications based on Java or other development frameworks such as .NET can not always be automated.
Web pages are not always developed with automation in mind. It is often necessary to create coding procedures within a development team to include the required properties within the elements to facilitate automation.
Locating Elements
There are various ways in which we can identify elements with the document.
- Viewing the source code directly.
- Using a DOM inspector
Automation
The following examples use Visual Basic Script to automate browser operations.
This function opens a browser and will then navigate to a web page.
Function OpenBrowser(url, sleepTime)
Dim IE
Set IE = CreateObject("InternetExplorer.Application")
IE.Visible = True
IE.Navigate2 url
Do
WScript.Sleep(sleepTime)
Loop while IE.Busy = TRUE
Set OpenBrowser = IE
End Function
A function to click on link.
Function ClickLink( byval oIE, strLnk)
Dim Link
For Each Link In oIE.Document.links
If Instr(strLnk, Link.href) > 0 Then
ClickLink = Link.href
Link.Click
Exit Function
End If
Next
ClickLink = ""
End Function
A basic script that uses the functions OpenBrowser and ClickLink to open up a web page and click on a link.
Set objBrowser = OpenBrowser ("www.google.com", 1000)
Call ClickLink(objBrowser, http://images.google.com/imghp?tab=wi)
More Methods to access objects in a web page.
Searching on google using the getElementsByName method
Dim IE
Set IE = CreateObject(“InternetExplorer.Application”)
IE.Visible = True
IE.Navigate2 “http://www.google.com/”
Do
WScript.Sleep(1000)
Loop while IE.Busy = TRUE
IE.document.getElementsByName(“q”)(0).value=“Classical Guitar”
IE.document.getElementsByName(“btnG”)(0).click
Set IE=Nothing
Frames - Problems within the DOM
In many cases we find that with an application that contains frames, very often we can’t access the elements inside some of the frames. This is caused by the frame having a different domain to the principal web page, causing access to the DOM of that frame to be denied. This is a security feature that stems from cross frame scripting. It basically stops unwanted access and changes occurring from outside of the domain of the frame; you can read more about it here http://msdn2.microsoft.com/en-us/library/ms533028.aspx. In a development environment developers can be made aware of this and can include the document.domain property to reference the principal domain inside of the frame. This allows access to the frames DOM.
Even though there are limitations to the DOM, there are many other objects such as xml based objects, and methods that can be used to assist us when DOM limitations are reached. A series on test automation frameworks is planned in the near future which will expand on the concepts learned in this series. You will learn how to develop a test automation framework using just VBScript and the API of an application such as Excel.
Conclusion
In this series we have looked at the various concepts involved in the automation of Internet Explorer. We have also described some very basic methods used in web application automation. We now how have a solid base to develop a test harness that takes advantage of these concepts.
For more information on TEST AUTOMATION FRAMEWORKS using VB and Excel. Please contact me through insideSQA.
