Let Assertions Return Either

[adius]

I think a structure like this would provide a much better separation of concerns:

shouldEqual :: String -> String -> Either String String
shouldEqual actual expected =
  if (actual /= expected)
  then Left "\"" <> actual <> "\" /= \"" <> expected <> "\""
  else Right ""


shouldBeOk :: forall r. Either String String -> Aff r Unit
shouldBeOk value = case value of
  Left error -> fail error
  Right _ -> (pure unit)


it "should do something" do
  shouldBeOk do
    actual <- getSomeEither
    expected <- getAnotherEither
    actual `shouldEqual` expected

Then all assertions would simply be of type String -> String -> Either String String

[adius]

Now that I think of it, is the current signature necessary to run it async? 🤔

[safareli]

@adius would be great if you can take a look at #82 because there i'm adding:
hoistSpec :: (m ~> g) -> Spec' m ~> Spec' g

It means you can use something other then Aff Unit for it blocks, so if you have use Either String Unit, then you can do hoistSpec (either throw pure) which will throw for all Left values.

[safareli]

/cc @ad-si

[owickstrom]

@safareli correct me if I'm wrong, but this means that if one wants to run Either-based specs for only a subset of a test suite, they could hoistSpec that suite into a larger Aff Unit-based suite.