ATGen: automatic test data generation using constraint logic programming and symbolic execution The verification and validation of software through dynamic testing is an area of software engineering where progress towards automation has been slow. In particular the automatic design and generation of test data remains, by and large, a manual activity. This is despite the high promises that the symbolic execution technique engendered when it was first proposed as a method for automatic test data generation. This paper presents an automatic test data generator based on constraint logic programming and symbolic execution. After reviewing the symbolic execution technique, approaches for the resolution of the technical difficulties that have so far prevented symbolic execution from reaching its full potential in the area of automatic test data generation are presented. ATGen, an automatic test data generator, based on symbolic execution and that uses constraint logic programming, is then discussed.