fakechroot: Add tests.nixos-etc

pkgs/tools/system/fakechroot/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, fetchpatch, autoreconfHook, perl }:
+{ lib, stdenv, fetchFromGitHub, fetchpatch, autoreconfHook, nixosTests, perl }:
 
 stdenv.mkDerivation rec {
   pname = "fakechroot";
@@ -44,6 +44,13 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ autoreconfHook ];
   buildInputs = [ perl ];
 
+  passthru = {
+    tests = {
+      # A lightweight *unit* test that exercises fakeroot and fakechroot together:
+      nixos-etc = nixosTests.etc.test-etc-fakeroot;
+    };
+  };
+
   meta = with lib; {
     homepage = "https://github.com/dex4er/fakechroot";
     description = "Give a fake chroot environment through LD_PRELOAD";