Marine safety & security is critical for Canada's coasts given the vulnerability of sea lanes, ports and harbors to a variety of threats and illegal activities. Decision support systems and simulation environments play a key role in facilitating surveillance operations. Meaningful results from simulation runs require appropriate test cases, the production of which is in itself a complex activity. In this paper, we propose an approach for the generation of test-cases for marine safety & security scenarios. The conceptual design issues including the main requirements, the architecture, and other detailed design issues of the proposed system are discussed. We also propose a formal representation of test-cases using the Abstract State Machine method and illustrate the approach by means of simple examples.