Catnap: generating test suites of constrained combinatorial testing with answer set programming. We develop an approach to test suite generation for constrained combinatorial testing (CCT), one of the most widely studied combinatorial testing techniques, based on answer set programming (ASP). The resulting catnap system accepts a CCT instance in fact format and combines it with a first-order encoding for generating test suites, which can subsequently be solved by any off-the-shelf ASP systems. We evaluate the effectiveness of our approach by empirically contrasting it to the best known bounds obtained via dedicated implementations.