1. A method of validating a widget on a Web page, comprising: generating a widget tree containing a hierarchy of context nodes and feature nodes, each of the context nodes and feature nodes corresponding to a feature under validation for an identified widget, the widget tree further corresponding to a subset of a first page tree structure for a first Web page; attaching the context nodes of the widget tree to nodes of the first page tree structure; performing a first feature extraction to obtain a first property value for each feature of interest corresponding to a context node or feature node in the widget tree, each first property value being a feature value or context node presence information; generating a first property vector including each first property value for the widget; loading and de-serializing a serialized expected property vector into an expected property vector; and comparing the first and expected property vectors to validate a functionality of the widget, wherein a functionality of the widget is validated if the first property vector matches the expected property vector.