Add mapToResult operator, tests

[kaphacius]

This PR adds a new operator catchToResult which allows transforming a Publisher that has a specific Failure type (not Never) into a publisher that outputs Output and Failure wrapped in a Result.
A common use-case for this is when an interface should produce publishers of type AnyPublisher<Result<T, Error>, Never>, but the underlying code works with publishers like AnyPublisher<T, Error> (URLSession.DataTaskPublisher).

The opposite situation, going from AnyPublisher<Result<T, Error>, Never> to AnyPublisher<T, Error> also happens. If there is an interest in this PR I can open another one with an operator that allows doing that.

[codecov]

Codecov Report

Merging #79 (5314a9d) into main (5b8a0c0) will increase coverage by 0.09%.
The diff coverage is 100.00%.

❗ Current head 5314a9d differs from pull request most recent head bea35a1. Consider uploading reports for the commit bea35a1 to get more accurate results

@@            Coverage Diff             @@
##             main      #79      +/-   ##
==========================================
+ Coverage   97.01%   97.10%   +0.09%     
==========================================
  Files          60       62       +2     
  Lines        3215     3315     +100     
==========================================
+ Hits         3119     3219     +100     
  Misses         96       96              

Impacted Files	Coverage Δ
Sources/Operators/MapToResult.swift	100.00% <100.00%> (ø)
Tests/MapToResultTests.swift	100.00% <100.00%> (ø)

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[manmal]

I think this looks great, thanks for taking up the idea!

[jasdev]

Would love to see this land, thanks @kaphacius! I use TCA’s catchToEffect analog often. ✅

The opposite situation, going from AnyPublisher<Result<Output, Failure>, Never> to AnyPublisher<Output, Failure> also happens. If there is an interest in this PR I can open another one with an operator that allows doing that.

+1.

(and as a heads up, we’ll probs need some quick docs. in the README.md, for when you get a chance. 🙏🏽)

[freak4pc]

Thanks! Tests look good overall, but there are some formatting issues, for example usage of unneeded parentheses, using keywords like catch and throw as functions (e.g. catch (let e), throw(MyError.error).

If you'll clean up these things I'll be happy to merge.

Thank you!

[kaphacius]

Added info to README.md and applied all of the suggested comments 👍

[jshier]

Is there any particular reason not to make the name of this something more general, like toResult? It's not strictly a catching operator, as it transforms the success case as well.

(I have this operator in my code base as asResult(), though I'm not particular on as vs. to.)

[freak4pc]

I agree about @jshier's remarks and this is the biggest gripe I have here. Something like maoToResult or something else makes more sense, but there's "prior art" with TCA's catchToEffect. Not sure that's really a strong enough reason to not give it our own naming.

[kaphacius]

I don't have any attachment to the name to be honest, I think mapToResult sounds equally good. I'll make the changes and update the PR

[kaphacius]

Renamed the operator, tests and the PR name :)

[freak4pc]

Looks great! Thank you :)