Explicitly list testTargets

`testTarget` is a space separated list of test-suites.

We explicitly list all test suites.
This allows us to implement logic in the nixpkgs builder to run test
suites in separate passthru.test derivations.

cabal2nix/src/Distribution/Nixpkgs/Haskell/FromCabal.hs

@@ -112,7 +112,7 @@ fromPackageDescription haskellResolver nixpkgsResolver missingDeps flags Package
     & jailbreak .~ False
     & doCheck .~ True
     & doBenchmark .~ False
-    & testTarget .~ mempty
+    & testTarget .~ unwords (map (unUnqualComponentName . testName) testSuites)
     & hyperlinkSource .~ True
     & enableSplitObjs .~ True
     & enableLibraryProfiling .~ False