Improving output: verbose mode

How currently the output looks like?

900 out of 1067  (wemake_python_styleguide/violations/consistency.py     should_use_text =                                                                                          FAILED: mutmut wemake_python_styleguide/violations/consistency.py --apply --mutation "    should_use_text = False⤑1"

901 out of 1067  (wemake_python_styleguide/violations/consistency.py     error_template =                                                                                           FAILED: mutmut wemake_python_styleguide/violations/consistency.py --apply --mutation "    error_template = 'Found parens right after a keyword'⤑0"

902 out of 1067  (wemake_python_styleguide/violations/consistency.py     error_template = 
903 out of 1067  (wemake_python_styleguide/violations/consistency.py     code = 313⤑0)

It shows two cases: failing and successful state. Let’s talk about both of them. I will also try to cover some general thoughts that I have.

First of all, I would like to analyze what happened. Since this process it rather long, I am not able to watch it in real time. The final output is also quite verbose, so it is hard to read it though. What do I suggest? It would be nice to have some short report that will cover:

1. What mutants managed to survive: what was changed, what was the change, in what file
2. What tests killed the most mutants (so these tests can be documented as important ones, etc), what tests did not caught any (so these tests might be removed in the future or refactored)

Secondly, it is possible to have better “inline experience”. What do I mean by that?

1. Currently when reading through the test cases I am missing some required information: what source line number was changed, to what, what mutation rule caused this
2. In case that the mutant was killed I guess we can show how many tests did fail. It would be very helpful and will give you a better understanding of what is going on

I would like to say, that this tool is absolutely awesome! Thank you for building it!

[boxed]

Well crap, the output is wrong. What you want to do is:

mutmut results

To show a diff of a mutant:

mutmut show 7

And to apply

mutmut apply 7

The mutation ids are just primary keys into the SQLite cache database now. This is a lot nicer to use imo.

[boxed]

I’m going to totally rework the output to remove this bug and make it nicer in some other ways.