#110 Restructure tests to use more mocking

[Bruce Merry]

The current scheme for testing tracing is tricky. It requires the test to do any necessary setup to make the state valid (creating objects etc), it is susceptible to bugs in the underlying implementation, and it depends on the underlying implementation providing the necessary extensions.

A mocking-based approach would allow for simpler and more complete testing. This would require replacing the "real" addresses with mocks, which should of course be generated.