Add sandbox build test

default.nix

@@ -125,5 +125,7 @@ let
     dummy = callPackage ./bsc/dummy/default.nix {
     };
 
+    chroot = callPackage ./test/chroot.nix {};
+
   };
 in pkgs // self

test/chroot.nix

@@ -0,0 +1,22 @@
+{stdenv}:
+
+stdenv.mkDerivation rec {
+  version = "0.0.1";
+  name = "chroot-checker";
+  src = ./chroot.nix;
+  dontUnpack = true;
+  buildPhase = ''
+    if [ -e /boot ]; then
+      echo Build is NOT under chroot
+      echo This is the content of / :
+      ls -l /
+      exit 1
+    fi
+
+    echo "OK: Build is under chroot"
+  '';
+
+  installPhase = ''
+    mkdir -p $out
+  '';
+}