Except for IO monads are values like anything else, at least in Haskell so ¡°testing monads¡± usually amounts to testing functions.
For fine grained tests I try to avoid IO and use either the Handler pattern to group all IO actions together, or a custom implementation of a type class if I use mtl style.
Arnaud?
Envoy¨¦ de mon iPhone
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Le 22 f¨¦vr. 2021 ¨¤ 00:53, J. B. Rainsberger <me@...> a ¨¦crit?:
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On Sat, Feb 20, 2021 at 1:12 PM Gregory Salvan <
apieum@...> wrote:
I never want test doubles, but I also rarely want end-to-end tests. Of course, there are no "stubs" in FP, but merely functions that return hardcoded values.
How do you test your edges ? your monads ?
I don't write monads yet, at least not intentionally. I presume that if I write them, then I use the equivalent of stubs, except that they aren't really stubs, but rather just functions as parameters. I treat them in my mind like OOP interfaces.
As for edges, I presume you mean the point of integration with something outside of the system? I write Learning Tests for the thing outside the system, which are usually integrated tests, and then at the point of integration I choose whether to integrate with the real thing or with a function that invokes the real thing.
--
J. B. (Joe) Rainsberger :: ?:: ::
--
J. B. (Joe) Rainsberger :: :: ::
Teaching evolutionary design and TDD since 2002
