purescript-spec/purescript-spec

forAll :: ∀ e a f. Foldable f => (a -> String) -> String -> f a -> (a -> Aff e Unit) -> Spec e Unit

safareli opened this issue · 6 comments

What are thoughts on adding something like this this?

forAll ::  e a f. Foldable f => (a -> String) -> String -> f a -> (a -> Aff e Unit) -> Spec e Unit
forAll itTitle title arb f = describe title do
  for_ arb \a -> it (itTitle a) (f a)

...
  forAll _.str "format (unformat a) = a" arb \({ str }) -> do
    (format $ unformat str) `shouldEqual` (Right str) 
...

I have been using for_ in it block but if some test case fails then other items are not tested and you can't see them in log. using this function you can see each item in log and all of them will be executed.

I would welcome utility functions like these as I have been re-inventing that wheel many times over for neodoc

Yeah, this does seem useful. I have some questions/considerations:

  • The name forAll feels like it's too close to forall. Would prefer something closer to it, as it's basically a "multi-it". Perhaps they?
  • I'd prefer to drop the outer describe in this definition, keeping it a bit simpler, and not making an assumption that you want a separate level for the foldable. I'm not sure, but you might want to do something like:
    describe "many things" do
      they show [2, 4] \n -> (n `mod` 2) `shouldEqual` 0
      they show [4, 8] \n -> (n `mod` 4) `shouldEqual` 0
  • And as a last thing, is the argument order the way we want? Not saying it isn't, but you might have feedback on that.

Thanks for the suggestion!

  • dropping out describe is good idea.
  • they seems good to me.

so at this point it looks like:

they ::  e a f. Foldable f => (a -> String) -> f a -> (a -> Aff e Unit) -> Aff e Unit
they itTitle arb f = for_ arb \a -> it (itTitle a) (f a)

...
  describe "format (unformat a) = a" do
    they show arb \(str) -> (format $ unformat str) `shouldEqual` (Right str) 
...

About order:

I don't have strong opinion on it, but If we leave f as last argument, then we have two options:

  • NAME itTitle arb f, infix usage: itTitle `NAME` arb f
  • NAME arb itTitle f, infix usage: arb `NAME` itTitle f
    I can't think of a good name (english is not my native language) but there might be some name which will best fit this usage. maybe that? (show `that` validDates parseAndUnparseComutes)

Yeah, I could not come with any specific order either, as it doesn't read naturally anyway. I think we should go with what you already have:

they ::  e a f. Foldable f => (a -> String) -> f a -> (a -> Aff e Unit) -> Aff e Unit

Would you like to submit this as a PR?

Would you like to submit this as a PR?

Yes!