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Image based testing basics

There are two approaches to black box GUI test automation, object oriented one and image based one.

Object oriented approachObject oriented testing tools are tightly integrated with a programming platform, for example .NET, C/C++, Java or alternatively the OS graphic interface (Win32 API, ...). They can typically retrieve application GUI component hierarchy and provide access to properties of individual GUI components such as buttons, check boxes, text fields, drop downs etc. Advantage of this approach is that you see the GUI structure from your test script and you can easily navigate through it or verify whether it has the expected content. Disadvantages of object oriented tools are that they can not test across different technologies and they often rely on certain platform version (and keep forcing you to upgrade as new versions get released).
 
Image based testing approachImage based testing tools analyze image of the tested application or the whole computer desktop. They get it usually from the underlying operating system, for example from the desktop image buffer or through attaching to the graphic driver. Advantage of this approach is that the underlying technology is irrelevant and the tool can test any application that displays on the desktop of the operating system. Such a testing is also simple, close to the end user experience and easy to learn even without programming experience. It can also reveal layout problems such as overlapping or ill fitting GUI components. Main disadvantage of this approach is no access to the application GUI component hierarchy.
 

T-Plan Robot Enterprise
is an image based testing tool. To overcome the the missing GUI hierarchy access it provides image comparison methods allowing to search for GUI components on the desktop and verify status of the tested application against image templates.

TIP: For a complete comparison of test approaches read our article Image Based Versus Object Oriented Testing.