Fine-tune output verbosity when assert fails (on dicts)

[stdedos]

I would envision that when a pytest fails, it would immediately show the different values on the input files.

(From now on, I'll assume that pytest-icdiff is also installed. I think the situation is even worse anyway)

Even without -v[v], I'd expect that this:

================================================== FAILURES ==================================================
...
>       assert original == new
E       AssertionError: assert equals failed
E               same_data_1            same_data_1
E               same_data_2            same_data_2
E               same_data_3            same_data_3
E               same_data_4            ...
E         
E         ...Full output truncated (20 lines hidden), use '-vv' to show

.../tests/test_balance.py:27: AssertionError
========================================== short test summary info ===========================================
FAILED .../tests/test_balance.py::... - AssertionError: assert equals failed
============================================= 1 failed in 0.47s ==============================================

would end up being a little bit more like that

================================================== FAILURES ==================================================
...
>       assert original == new
E       AssertionError: assert equals failed
...
E               'a': [{'b': 0, 'cdef_ghij': 'k', 'l': [6]}],       'a': [{'b': 0, 'cdefGhij': 'k', 'l': [6]}],
                                                                       
E         ---                                                                          ---                     
...                        
E           'keyB': 0,                                                                                         
...

.../tests/test_balance.py:27: AssertionError
========================================== short test summary info ===========================================
FAILED .../tests/test_balance.py::... - AssertionError: assert equals failed
============================================= 1 failed in 0.47s ==============================================

(/^...$/ MAY or MAY NOT contain output i.e., ...\n --> \0).

The output could be still verbose (i.e. no -v[v] specific), and still have some output on <3 lines. It also be exactly what's needed.

Since there will be some output anyway, I don't know if the current output is actually helpful, or not.

The idea was born after figuring out the --tb=... flags.
I'd like to avoid -v[v], since I don't know "what else does it affect".
(e.g., I like the normal output, but I want no stacktraces, but I am okay diffs <5 lines being immediately visible)

---

PS: I avoided opening an issue, since maybe all of that is intentional on pytest