Several test generation techniques have been proposed in the literature. These techniques target separately specific levels of testing without relating them to each other in order to avoid redundancy and enable reuse and optimization. In this chapter, we look into connecting different levels of testing. We propose a model-based testing framework that enables reusability and optimization across different levels of testing. Test cases at one level are reused to generate test cases of subsequent levels of testing. Furthermore, test cases at one level are optimized by relating them to test cases of preceding testing levels and removed if they are found redundant.