I. Introduction
With grammar-based test generation (GBTG), test cases are specified with a grammar . A generator reads and generates : the language accepted by the grammar. Usually is so large that it is not practical to execute all of the generated cases. Therefore, GBTG tools support “tags:” extra-grammatical annotations that restrict the generation. GBTG is well-suited to generating structured test inputs, e.g., programs for compiler testing or eXtensible Markup Language (XML) files for web testing.