Assertions for the Tcl Language

Assertions, even as simple as the C assert macro, offer important self-checking properties to programs, and improve the robustness of software when they are used. This paper describes ASSERTCL, an assertion package for the Tcl programming language. Our assertions take the form of commands in the program text, and cover point assertions about the computation state, assertions about procedure input values and the return value, and assertions about the values that variables may take on over their whole lifetime. In addition, universal and existential quantifiers are provided for both lists and arrays, not only for individual elements, but for sequences of elements as well.