Give information on how to re-run specific spec items on test failure

[sol]

Print information on how to rerun with -m and --rerun. This should be aware of runhaskell and GHCi, e.g. in ghci it should say :main ....

Possibly, we want to introduce some "novice"-mode and make it less verbose if it is off.

[prikhi]

I still don't know how this is done... Could you explain it so I don't have to wait for the patch :P

I'm running with cabal test. Does -m use file names? or the text in describe? or the text in it? Or the test function names? I have no idea...

[sol]

@prikhi It use a combination of the arguments of describe and it. You can either match on the pretty-printed description or on all components joined by /, or any substring of any of the two.

Let's walk through an example:

-- Spec.hs
import           Test.Hspec

main :: IO ()
main = hspec $ do
  describe "Prelude" $ do
    describe "reverse" $ do
      it "reverses a list" False
    describe "show" $ do
      it "shows its argument" True

$ runhaskell Spec.hs 

Prelude
  reverse
    reverses a list FAILED [1]
  show
    shows its argument

1) Prelude.reverse reverses a list

Randomized with seed 48919573

Finished in 0.0008 seconds
2 examples, 1 failure

You now can rerun the failing spec by matching on the pretty-printed description Prelude.reverse reverses a list of the error message:

$ runhaskell Spec.hs -m "Prelude.reverse reverses a list"

Or you can join all the components with / and match on Prelude/reverse/reverses a list:

$ runhaskell Spec.hs -m "Prelude/reverse/reverses a list"

Or any substring of one of the above, e.g.:

$ runhaskell Spec.hs -m reverse

[sol]

If you use ghci you can use --rerun to rerun failing specs:

$ ghci Spec.hs                          
*Main> :main
...
*Main> :main --rerun
...

[sol]

If you are inclined to use cabal, try:

$ cabal configure --enable-tests --disable-optimization
$ cabal build && ./dist/build/spec/spec -m reverse

[sol]

Also note that both ghci and runhaskell can be used with cabal sandboxes, but you may need to pass additional arguments. Here are examples for the common src//test/ layout:

$ cabal exec -- runhaskell -isrc -itest test/Spec.hs

$ cabal exec -- ghci -isrc -itest test/Spec.hs

[sol]

Also have a look at https://github.com/sol/hspec-example#running-tests

[prikhi]

Beautiful thank you :D

Unfortunately my current use case is integration tests using hspec-webdriver and that seems to not play too nice with either the -m or --rerun flags(it only works if I target the base Spec, otherwise I get BlockedIndefinitelyOnMVar).

Ah well, good to know for the future, thanks!

[sol]

That sounds scary, probably a bug in hspec-webdriver.

[sol]

I added this to the docs https://hspec.github.io/match.html