For Leo's interest in writing short programs specifically for automated testing, the most useful tutorial would be "Writing Test Scripts." This tutorial would likely cover various approaches to creating automated tests, including how to write scripts that can efficiently test software functionality.
While the other topics are important aspects of the software development lifecycle, they focus more on requirements specification and acceptance testing rather than the direct creation of programs for automation. Therefore, focusing on writing test scripts would be most beneficial for learning how to automate testing processes.