I have a simple TestInstance in a detailed-0.9 test suite:

tests :: IO [Test]
tests = return [Test testInstance]

testInstance :: TestInstance
testInstance =
  TestInstance
    { run = ioProgress,
      name = "test 1",
      tags = [],
      options = [],
      setOption = _ _ -> Left ""
    }

ioProgress :: IO Progress
ioProgress = progress 3
  where
    progress :: Int -> IO Progress
    progress 0 = return (Finished (Fail "failed"))
    progress n = return (Progress ("n == " ++ show n) (progress (n - 1)))

I thought that maybe I would see some output like

n == 3
n == 2
n == 1

whilst the test runs but I never see these strings, even with --test-show-details=always and --test-show-details=streaming.