Allow configuration of passthrough during BaseResponse construction

[jayaddison]

Resolves #557.

[beliaev-maksim]

please add this change for 0.22 in the log: https://github.com/getsentry/responses/blob/master/CHANGES

also, do we need then class attribute ?

[markstory]

Seems reasonable to me. It would be good to update the docs and changelog for this.

[jayaddison]

also, do we need then class attribute ?

Good question. I've left it as-is for now for backwards-compatibility, although I have replaced the mention of it in the documentation.

Perhaps it could make sense to remove it. Pattern-wise, perhaps we'd want to recommend that Response objects should be mostly/completely immutable after they are created?

[jayaddison]

Thanks @beliaev-maksim!

[codecov]

Codecov Report

Merging #558 (580cbac) into master (3d83a88) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #558   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         7           
  Lines         2561      2581   +20     
=========================================
+ Hits          2561      2581   +20     

Impacted Files	Coverage Δ
responses/__init__.py	100.00% <100.00%> (ø)
responses/tests/test_responses.py	100.00% <100.00%> (ø)

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[markstory]

Thank you 🎉

[jayaddison]

Thanks @markstory!