make cabal test run our unit tests

Setup.hs

@@ -1,4 +1,12 @@
 #!/usr/bin/env runhaskell
 import Distribution.Simple
+import Distribution.Simple.LocalBuildInfo
+import Distribution.PackageDescription
+import System.FilePath
+import System.Process
 
-main = defaultMain
+main = defaultMainWithHooks $ simpleUserHooks{runTests=runTests'}
+
+runTests' :: Args -> Bool -> PackageDescription -> LocalBuildInfo -> IO ()
+runTests' _ _ _ lbi = system testprog >> return ()
+    where testprog = (buildDir lbi) </> "hledger" </> "hledger test"

hledger.cabal

@@ -21,7 +21,7 @@ bug-reports:    http://code.google.com/p/hledger/issues
 stability:      experimental
 tested-with:    GHC==6.8, GHC==6.10
 cabal-version:  >= 1.2
-build-type:     Simple
+build-type:     Custom
 
 extra-tmp-files:
 extra-source-files: