Add verbose modes for easier handler debugging

[stickies-v]

With the runner spawning the handler process, debugging test failures is currently a bit involved. Since handlers take input from stdin, they can very easily be manually tested on command line with echo <request> | <handler-bin>.

I propose adding -v (verbose on failure) and -vv (always verbose) args (potentially also a --verbosity={0,1,2}), where:

• -v will print the full request and response for each failed test
• -vv will print the full request and response for each test

This way, the failed tests can easily be replicated manually with a simple copy-paste.

[stringintech]

Cool! That should be helpful indeed.
I wanted to address this after opening #11. Do you think this feature could evolve to also support stateful tests?

[stickies-v]

Do you think this feature could evolve to also support stateful tests?

statefulness was not yet on my radar when I opened this issue, so I haven't thought about it much yet.

Consider the scenario: func A produces ref $a through request req_a. func B then takes the $a reference parameter through request req_b, and fails. Ideally, -v would unwind this stack trace by first printing req_b, and then recursively going through its reference parameters and printing all those requests too?

If that proves too complicated to implement, I think just printing the top-level failed request would already provide a lot of benefit though.

[stringintech]

The recursive approach makes sense. I will work on it. Thanks!

[stringintech]

Last commit in #11 addresses this. It got a bit more involved since state mutations had to be taken into account too (i.e., btck_chainstate_manager_process_block has an effect on the result of btck_chain_get_height), so I introduced a separate entity for it (DependencyTracker) along with unit tests. Also, README.md has been updated to explain the verbose flags, including a sample output.

I propose adding -v (verbose on failure) and -vv (always verbose) args (potentially also a --verbosity={0,1,2}), where:

I implemented -v and -vv. Internally, three enum levels are introduced, so adding another flag for verbosity should be straightforward. Let me know if you think having that as well would be helpful.