Run 'doctest' via 'cabal repl'

test/doctest/Doctest.hs

@@ -1,10 +1,10 @@
--- | Rn the doctest executable
+-- | Run the doctest executable
 module Main (main) where
 
 import System.Process (callProcess)
 
-doctest :: [String] -> IO ()
-doctest = callProcess "doctest"
+doctest :: IO ()
+doctest = callProcess "cabal" ["repl", "--with-ghc=doctest"]
 
 main :: IO ()
-main = doctest ["--fast", "src"]
+main = doctest