with import "${builtins.getEnv "_NIX_TEST_BUILD_DIR"}/config.nix"; mkDerivation { name = "filter"; builder = builtins.toFile "builder" "ln -s $input $out"; input = let filter = path: type: type != "symlink" && baseNameOf path != "foo" && !((import ./lang/lib.nix).hasSuffix ".bak" (baseNameOf path)); in builtins.filterSource filter ((builtins.getEnv "TEST_ROOT") + "/filterin"); }