Automatic Generation of Normal Forms for Testing Object-Oriented Software

Testing object-oriented software is more complex than its procedural counterpart. The concept of "fundamental pairs" was introduced in our TACCLE methodology for testing object-oriented software. It was proved that, although the set of fundamental pairs is only a proper subset of equivalent ground terms, the use of fundamental pairs as test cases covers the use of equivalent ground terms. Recently, we found that any normal form consists of only a creator, or a creator followed only by constructors but not transformers; and yet the reverse is not necessarily true. Thus, the generation of patterns of normal forms is nontrivial and warrants further study. Motivated by this finding and based on further pattern analyses of normal forms and tree models with pruning techniques, we propose an algorithm to generate representative normal forms according to patterns and develop a corresponding automatic tool. This work improves the automation, coverage, and adequacy of selecting (equivalent) fundamental pairs as test cases.