4 files changed, 41 insertions, 10 deletions
diff --git a/haddock-test/haddock-test.cabal b/haddock-test/haddock-test.cabal
index 6b6c9fd8..48314600 100644
--- a/haddock-test/haddock-test.cabal
+++ b/haddock-test/haddock-test.cabal
@@ -16,7 +16,7 @@ library
   default-language: Haskell2010
   ghc-options: -Wall
   hs-source-dirs:   src
-  build-depends:    base >= 4.3 && < 4.12, bytestring, directory, process, filepath, Cabal, xml, xhtml, syb
+  build-depends:    base >= 4.3 && < 4.13, bytestring, directory, process, filepath, Cabal, xml, xhtml, syb
 
   exposed-modules:
     Test.Haddock
diff --git a/haddock-test/src/Test/Haddock.hs b/haddock-test/src/Test/Haddock.hs
index f372f773..942c0587 100644
--- a/haddock-test/src/Test/Haddock.hs
+++ b/haddock-test/src/Test/Haddock.hs
@@ -158,7 +158,9 @@ maybeAcceptFile :: Config c -> FilePath -> CheckResult -> IO CheckResult
 maybeAcceptFile cfg file result
     | cfgAccept cfg && result `elem` [NoRef, Fail] = do
         Just out <- readOut cfg file
-        writeFile (refFile dcfg file) $ ccfgDump ccfg out
+        let ref = refFile dcfg file
+        createDirectoryIfMissing True (takeDirectory ref)
+        writeFile ref $ ccfgDump ccfg out
         pure Accepted
   where
     dcfg = cfgDirConfig cfg
diff --git a/haddock-test/src/Test/Haddock/Config.hs b/haddock-test/src/Test/Haddock/Config.hs
index 8b395b6c..51032a3a 100644
--- a/haddock-test/src/Test/Haddock/Config.hs
+++ b/haddock-test/src/Test/Haddock/Config.hs
@@ -15,8 +15,9 @@ import Control.Monad
 import qualified Data.List as List
 import Data.Maybe
 
+import Distribution.Text
+import Distribution.Types.PackageName
 import Distribution.InstalledPackageInfo
-import Distribution.Package
 import Distribution.Simple.Compiler hiding (Flag)
 import Distribution.Simple.GHC
 import Distribution.Simple.PackageIndex
@@ -256,15 +257,44 @@ baseDependencies ghcPath = do
     concat `fmap` mapM (getDependency pkgIndex) pkgs
   where
     getDependency pkgIndex name = case ifaces pkgIndex name of
-        [] -> do
-            hPutStrLn stderr $ "Couldn't find base test dependency: " ++ name
+      [] -> do
+        hPutStrLn stderr $ "Couldn't find base test dependency: " ++ name
+        exitFailure
+
+      (unit, ifaceOpt, htmlOpt) : alts -> do
+        when (not . null $ alts) $
+          hPutStr stderr $ unlines
+            [ "Multiple options found for base test dependency: " ++ name
+            , "Choosing the first of these, which has unit id: " ++ unit
+            ]
+
+        case (ifaceOpt, htmlOpt) of
+          (Nothing, _) -> do
+            hPutStr stderr $
+              "No '.haddock' file found for base test dependency: " ++ name
             exitFailure
-        (ifArg:_) -> pure ["--optghc=-package" ++ name, ifArg]
+
+          (Just iface, Nothing) -> do
+            hPutStrLn stderr $
+              "No HTML directory found for base test dependency: " ++ name
+            pure [ "--optghc=-package" ++ name
+                 , "--read-interface=" ++ iface
+                 ]
+
+          (Just iface, Just html) ->
+            pure [ "--optghc=-package" ++ name
+                 , "--read-interface=" ++ html ++ "," ++ iface
+                 ]
+
     ifaces pkgIndex name = do
         pkg <- join $ snd <$> lookupPackageName pkgIndex (mkPackageName name)
-        iface <$> haddockInterfaces pkg <*> haddockHTMLs pkg
-    iface file html = "--read-interface=" ++ html ++ "," ++ file
 
+        let unitId = display (installedUnitId pkg)
+            ifaceOpt = listToMaybe (haddockInterfaces pkg)
+            htmlDirOpt = listToMaybe (haddockHTMLs pkg)
+
+        pure (unitId, ifaceOpt, htmlDirOpt)
+    
 
 defaultDiffTool :: IO (Maybe FilePath)
 defaultDiffTool =
diff --git a/haddock-test/src/Test/Haddock/Xhtml.hs b/haddock-test/src/Test/Haddock/Xhtml.hs
index 69361f7c..8bfc973f 100644
--- a/haddock-test/src/Test/Haddock/Xhtml.hs
+++ b/haddock-test/src/Test/Haddock/Xhtml.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE StandaloneDeriving #-}
-
+{-# OPTIONS_GHC -fno-warn-orphans #-}
 
 module Test.Haddock.Xhtml
     ( Xml(..)
@@ -22,7 +22,6 @@ newtype Xml = Xml
     } deriving Eq
 
 
--- TODO: Find a way to avoid warning about orphan instances.
 deriving instance Eq Element
 deriving instance Eq Content
 deriving instance Eq CData