Widgets or other code modules for applications written in structured languages such as HTML can be tested advantageously by separating the extraction and validation logic. To test the functionality of a widget in response to an action, widget features of interest are identified. Context and feature nodes for these features are extracted from a page tree structure to generate a property vector that is representative of the state of the widget. After performing the action, context nodes for the features are attached to the new page tree for the newly loaded page, and an observed property vector is generated that represents the state of the widget after the action. The previous property vector is used with updated state information to generate an expected property vector. The observed property vector is compared with the expected property vector, and if the vectors match the validation is claimed to be successful.