Abstract
Regression testing is an important software maintenance activity. The existing regression testing techniques are mostly code-based. This paper presents a specification-based regression testing technique for classes specified in Timed Communicating Object-Z (TCOZ) notation, which is an integrated formal modelling notation for the design of complex systems. To reduce the cost of regression testing, a TCOZ-based regression test selection algorithm is presented; it selects test cases relevant to the changed specifications from the original test suite for use in regression testing. This paper also describes TcozRts, a TCOZ specification-based regression testing system that implements our technique. The technique is strictly specification-based, and it doesn?t require any assumptions about the programming language that is used to implement the specification.