swift: enable tests (WIP)

add check phase for running some of the Swift test suite

A small number of tests is failing, which needs investigation,
so the check phase remains disabled by default.

pkgs/development/compilers/swift/default.nix

@@ -250,9 +250,19 @@ stdenv.mkDerivation rec {
       --replace usr/lib "$PREFIX/lib"
   '';
 
+  buildPhase = builder;
+
   doCheck = false;
 
-  buildPhase = builder;
+  checkInputs = [ file ];
+
+  # TODO: investigate the non-working tests
+  checkPhase = ''
+    checkTarget=check-swift-all
+    ninjaFlags='-C buildbot_linux/swift-${stdenv.hostPlatform.parsed.kernel.name}-${stdenv.hostPlatform.parsed.cpu.name}'
+
+    ninjaCheckPhase
+  '';
 
   installPhase = ''
     mkdir -p $out