  Cross-coverage of a program P refers to the test coverage measured over a
different program Q that is functionally equivalent to P. The novel concept of
cross-coverage can find useful applications in the test of redundant software.
We apply here cross-coverage for test suite augmentation and show that
additional test cases generated from the coverage of an equivalent program,
referred to as cross tests, can increase the coverage of a program in more
effective way than a random baseline. We also observe that -contrary to
traditional coverage testing-cross coverage could help finding (artificially
created) missing functionality faults.
