By having two modules that declare and use the `harness` module we ran
into a situation where not all parts of the `harness` module were
being used by both of these other test modules. This was producing
annoying warnings.
For now this can be solved by marking the `harness` module declaration
as public. This has no real effect since modules under `/tests` cannot
be depended on elsewhere, but it satisfies the compiler. It does mean
that we will not hear about unused functions, but this change should
be temporary and it's a very minor problem given that it's just test
code.
Previously we were testing the protocol by manually driving Alice and
Bob's state machines. This logic has now be moved to an async state
transition function that can take any possible state as input. The
state transition function is called in a loop until it returns the
desired state. This allows use to interrupt midway through the protocol
and perform refund and punish tests. This design was chosen over a
generator based implementation because the the generator based
implementation results in a impure state transition function that is
difficult to reason about and prone to bugs.
Test related code was extracted into the tests folder.
The 2b and 4b states were renamed to be consistent with the rest.
Macros were used to reduce code duplication when converting
child states to their parent states and vice versa.
Todos were added were neccessary.
