Simplify DocTestMain thanks to doctest-parallel-0.2.2

Manually filtering out auto-generated modules like `Paths_` is no
longer needed with doctest-parallel-0.2.2.

Author: andreasabel

hackage-server.cabal

@@ -572,4 +572,5 @@ test-suite DocTests
 
   build-depends:
     , lib-server
-    , doctest-parallel ^>= 0.2.1
+    , doctest-parallel ^>= 0.2.2
+        -- doctest-parallel-0.2.2 is the first to filter out autogen-modules

tests/DocTestMain.hs

@@ -1,18 +1,12 @@
 -- | `doctest-parallel` runner for `hackage-server` library.
 module Main where
 
-import Data.List
-         ( isPrefixOf )
 import System.Environment
          ( getArgs )
-
-import Distribution.ModuleName
-         ( components )
-
 import Test.DocTest
          ( mainFromLibrary )
 import Test.DocTest.Helpers
-         ( Library(..), extractSpecificCabalLibrary, findCabalPackage )
+         ( extractSpecificCabalLibrary, findCabalPackage )
 
 -- | Doctest @hackage-server:lib-server@.
 main :: IO ()
@@ -21,7 +15,4 @@ main = do
   pkg  <- findCabalPackage "hackage-server"
   -- Need to give the library name, otherwise the parser does not find it.
   lib  <- extractSpecificCabalLibrary (Just "lib-server") pkg
-  -- Need to filter out the @Paths_*@ modules, as they are not found by doctest-parallel.
-  let f    = not . ("Paths_" `isPrefixOf`) . head . components
-  let lib' = lib{ libModules = filter f $ libModules lib }
-  mainFromLibrary lib' args
+  mainFromLibrary lib args