This paper describes an ongoing research on test case generation based on Unified Modeling Language (UML). The described approach builds on and combines existing techniques for data and graph coverage. It first uses the Category-Partition method to introduce data into the UML model. UML Use Cases and Activity diagrams are used to respectively describe which functionalities should be tested and how to test them. This combination has the potential to create a very large number of test cases. This approach offers two ways to manage the number of tests. First, custom annotations and guards use the Category-Partition data which allows the designer tight control over possible, or impossible, paths. Second, automation allows different configurations for both the data and the graph coverage. The process of modeling UML activity diagrams, annotating them with test data requirements, and generating test scripts from the models is described. The goal of this paper is to illustrate the benefits of our model-based approach for improving automation on software testing. The approach is demonstrated and evaluated based on use cases developed for testing a graphical user interface (GUI).