Provide methods for checking for potential breaking changes in events and commands between versions

[jonsequitur]

A useful feature in Its.Domain.Testing would be methods for allowing event and command signatures and serialization to be checked against past known forms during test runs, so that breaking contract changes can be caught as early as possible.

[jonsequitur]

Using ApprovalTests is a great way to accomplish this. Some support in Its.Domain.Testing may make that task simpler. Or maybe similar functionality is worth baking into Its.Domain.Testing since this is such a critical piece.