Automate your UI using Microsoft automation framework

Introduction

UI automation is a programmatic interface to the user interface of your application to external applications that may be interested in programmatic communication with your UI. In fact UI automation is the prime facilitator for accessibility features in Windows where external applications such as screen readers that have no clue about your application, can still interact with your application easily.

I was acquainted with UI automation during my tenure at Microsoft in 2005 when I started working as software developer in test within Visual Studio Team Architects team on a project called Whitehorse. For those who need some background, Whitehorse consisted of SOA diagrams within Visual Studio (you can learn more about this project in the MSDN magazine here). Testing of visual designers in the product test team was done entirely using an internal UI test automation framework built on top of Microsoft Active Accessibility framework.

The UI automation framework is relatively new to Windows platform and successor to Windows Active Accessibility. The framework provides a unified way to discover UI controls in an application built using any of the following desktop technologies: Win32, Windows Forms or WPF.

UI automation has several benefits when used in applications:

Accessibility features – UI automation provides accessibility support in your application. Accessibility support becomes even more important when there are matter of legal compliance in the domain your application is used in (e.g. Government regulations).
Automated UI testing – UI automation can automate testing for application UI saving time and costs associated with manual and regression testing. Moreover given a set of use cases, UI automation can be used to verify application behavior via scenario tests.
Custom controls – If you are authoring custom controls, UI automation support enables end clients of your control to automate your control in their application UI.

How does automation work?

UI automation provides a common protocol for exchanging information between your application and an external entity such as screen reader or automated UI tests. UI automation provides an API using which an external application can discover controls, navigate the visual tree, access the state of the controls and perform control specific actions.

In WPF, automation object model is provided via System.Windows.Automation.AutomationElement instance associated with a UIElement (said to be “automation peer” of the control). If you are authoring a custom control, you may want to implement one or more interfaces defined in the UIAutomationProvider.dll under the System.Windows.Automation.Provider namespace to support UI automation.

To support UI automation, a control author needs to implement an abstract class AutomationPeer from UIElement class’ virtual method OnCreateAutomationPeer. AutomationPeer  is then used at runtime to extract AutomationElement for the UIElement. It is important to note that the standard controls in WPF have standard implementation of AutomationPeer associated with the controls out of the box. In authoring a derivative of AutomationPeer you may want to subclass a standard implementation rather than deriving directly from AutomationPeer and authoring a class from scratch.

Read more: Codeproject

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