nixos/tests/storage: Fix exporting storage.xml

Using copyFileFromHost() doesn't work if the file contains single
quotes, because they're not escaped properly.

So let's move to a more robust way to provide storage.xml to the
guests (via environment.etc), because apart from that escaping issue we
really don't need anything like copyFileFromHost() anymore because every
subtest now resides in its own derivation.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

nixos/tests/storage.nix

@@ -11,6 +11,13 @@ let
         pkgs.nixpart pkgs.file pkgs.btrfs-progs pkgs.xfsprogs pkgs.lvm2
       ];
       virtualisation.emptyDiskImages = [ 4096 4096 ];
+      environment.etc."storage.xml".text = let
+        config = (import ../lib/eval-config.nix {
+          modules = pkgs.lib.singleton attrs.config;
+        }).config;
+      in builtins.toXML {
+        inherit (config) storage fileSystems swapDevices;
+      };
     };
 
     testScript = ''
@@ -44,14 +51,7 @@ let
       }
 
       sub nixpart {
-        $machine->copyFileFromHost('${let
-          config = (import ../lib/eval-config.nix {
-            modules = pkgs.lib.singleton attrs.config;
-          }).config;
-        in pkgs.writeText "storage.xml" (builtins.toXML {
-          inherit (config) storage fileSystems swapDevices;
-        })}', "/storage.xml");
-        $machine->succeed("nixpart -v --from-xml /storage.xml");
+        $machine->succeed("nixpart -v --from-xml /etc/storage.xml");
         ensureSanity;
       }
 
@@ -94,7 +94,7 @@ let
             die;
           }
           # Try to remount with nixpart
-          $machine->succeed("nixpart -vm --from-xml /storage.xml");
+          $machine->succeed("nixpart -vm --from-xml /etc/storage.xml");
           ensureMountPoint("/mnt");
           # Check if our beloved canaries are dead
           chomp $canaries;