Two-dimensional Approximation Coverage

The notion of approximation coverage is developed. It is applicable to first-order declarative programs (e.g., logic programs, constructive algebraic specifications, and attribute grammars) in two dimensions in a natural way. For an attribute grammar, for example, there is a syntactic dimension corresponding to the underlying context-free grammar, and there is also a semantic dimension corresponding to the attributes, conditions, and computations. The coverage notion is based on an abstract interpretation scheme. The paper also develops a generator algorithm for test sets achieving coverage. The coverage notion facilitates testing of declarative programs, and assessment of test sets. The test set generator facilitates automated testing. A language definition based on an attribute grammar specification is used as an illustrative example.