purescript / purescript-assert Goto Github PK

Since we have assert' that throws with a user-supplied message, why not having these? That's what the user might expect.

Some libraries outside of core use this library as their way of testing. The problem is that the output is pretty hard to understand. How would we feel about adding a few small helpers to make the output better?

assertEqual ∷ forall a eff. Eq a => Show a => { expected :: a, actual :: a } -> Eff (assert :: ASSERT | eff) Unit
assertEqual {actual, expected} = do
  unless result $ log message
  assert' message result
  where
  message = "Expected: " <> show expected <> "\nActual:   " <> show actual
  result = actual == expected

assertTrue :: forall eff. Boolean -> Eff (assert :: ASSERT | eff) Unit
assertTrue actual = assertEqual { actual, expected: true }

assertFalse :: forall eff. Boolean -> Eff (assert :: ASSERT | eff) Unit
assertFalse actual = assertEqual { actual, expected: false }

Another thing that bothers me a little is that the full error message in assertEqual gets evaluated even if it is not needed. show can be quite expensive for large inputs.

Possible fix is to delay the first argument of assert' (some renaming should also be done to avoid breaking the API)

foreign import assert'
  :: (Unit -> String)
  -> Boolean
  -> Effect Unit

Should I make a PR for this issue, or is it too insignificant to care about?