When performing a LoadTest user actions are simulated. This implicates that mouse or keyboard actions are executed based on a script, based on a scenario, and that the script waits for a response on the screen.
The response on the screen can be determined using API’s giving information about windows present, or the controls on the windows. For instance: the script waits until a window is active with the caption "Microsoft Word".
Another way of determing if a response is given is by comparing the content of the screen with a bitmap. For instance: the script waits until an empty document is displayed in Microsoft Word.
The difference between the two techniques is that a window caption is present right when the application is launched (even if the application is still loading) while the content on the screen is more simular to the way users interact in a session. So looking at a screen region is more accurate, it prevents assumptions (best practice #9 in loadtesting best practices) like "how much time should we wait between lauching an application and clicking on a menu?”.
In this article I will be discussing some best about practices about “true” client side testing (best practice #12 in loadtesting best practices).