Web Add-in Extensibility Developer Guide > Working with Web Add-in Extensibility > Developing Support for Your Toolkit > Understanding the Test Object Configuration File > Extending an Existing Test Object Class

Extending an Existing Test Object Class

If there is an existing test object class that provides partial support for your control, but needs some modification, for example, a different naming convention for test objects in the class, or additional or modified test object methods, you create a new test object class to represent the control. When you create the new test object class, you base this test object class on the existing test object class, inheriting all of its test object methods.

You can then extend the functionality of this test object class by defining and implementing additional test object methods and identification properties. In addition, you can override existing test object methods by providing an alternate implementation for them. You define the new or changed methods and properties in the test object configuration file, and design their implementation using JavaScript functions.

To extend an existing test object class, you define the name of the base test object class in the ClassInfo\BaseClassInfoName attribute in the ClassInfo element for the new test object class in the test object configuration file. This declares that the new test object class supports all of the test object methods of the base test object class in addition to any that you define for the new test object class.