White-box testing exercises a software system by ensuring that a model of the internal structure is covered by the test cases. Extending this approach to Web applications is far from obvious, because at least two abstraction levels can be considered to represent the internal structure of a Web application: the navigation model and the control flow model. To further complicate the matter, dynamic code generation must be taken into account in both models. In this paper, the two alternative models are presented and white-box testing criteria are defined on them. Their usage for the white-box testing of a real-world Web application is described, highlighting the associated costs and benefits.