Introduce skip_cache_func

[VitalyPetrov]

• add an optional value_checker param to cache decorator classes cached, cached_stampede and multi_cached
• add IDE-specific folders to gitignore
• add black formatter to `requirements-dev.txt

Are there changes in behavior for the user?

Did not test in real production code

Related issue number

Fixes #649

Checklist

• [+] I think the code is well written
• [-] Unit tests for the changes exist
• [+] Documentation reflects the changes
• [-] Add a new news fragment into the CHANGES folder

[VitalyPetrov]

Unit tests for that functionality is not done yet.
As for notes in CHANGES the PR seems to be too small to be released separately IMO. But the choice Is yours (maintainers).

[Dreamsorcerer]

Thanks.

A couple of suggestions there, and we'll also need some tests for the new behaviour (maybe in tests/acceptance/tests_decorator.py so it gets tested against the different backends).

[Dreamsorcerer]

Ignore the news fragment. I'm not sure where that checklist comes from, trying to see if I can edit it...

[VitalyPetrov]

Updated the code, please check

[codecov]

Codecov Report

Merging #652 (2e24baf) into master (0cedbb2) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #652   +/-   ##
=======================================
  Coverage   99.67%   99.67%           
=======================================
  Files          35       35           
  Lines        3707     3743   +36     
=======================================
+ Hits         3695     3731   +36     
  Misses         12       12           

Flag	Coverage Δ
unit	99.67% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
aiocache/decorators.py	100.00% <100.00%> (ø)
tests/acceptance/test_decorators.py	100.00% <100.00%> (ø)

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[Dreamsorcerer]

OK, looking good. If we can just get a couple of tests in (maybe in tests/acceptance/tests_decorator.py?), then we're good to merge.

[VitalyPetrov]

Done with tests

[Dreamsorcerer]

Added cached_stampede to the tests to get full coverage, all good now.

Thanks a lot for that.