anchor.diff:      machine = { pkgs, lib, ... }: {
         environment.systemPackages = [ pkgs.socat ]; # for the socket activation stuff
         users.mutableUsers = false;
  +
  +      # For boot/switch testing
  +      system.build.installBootLoader = lib.mkForce (pkgs.writeShellScript "install-dummy-loader" ''
  +        echo "installing dummy bootloader"
  +        touch /tmp/bootloader-installed
  +      '');
   
         specialisation = rec {
           simpleService.configuration = {
  
positive.code: 
          # Start a simple service
          out = switch_to_specialisation("${machine}", "simpleService")
          assert_lacks(out, "stopping the following units:")
          assert_lacks(out, "NOT restarting the following changed units:")
          assert_contains(out, "reloading the following units: dbus.service\n")  # huh
  
negative.code:         "${stderrRunner} ${otherSystem}/bin/switch-to-configuration test"
      )
  
  
      with subtest("actions"):
          # boot action
          machine.fail("test -f /tmp/bootloader-installed")
          out = switch_to_specialisation("${machine}", "simpleService", action="boot")
          assert_contains(out, "installing dummy bootloader")
          assert_lacks(out, "activating the configuration...")  # good indicator of a system activation
          machine.succeed("test -f /tmp/bootloader-installed")
          machine.succeed("rm /tmp/bootloader-installed")
  
          # switch action
          machine.fail("test -f /tmp/bootloader-installed")
          out = switch_to_specialisation("${machine}", "", action="switch")
          assert_contains(out, "installing dummy bootloader")
          assert_contains(out, "activating the configuration...")  # good indicator of a system activation
          machine.succeed("test -f /tmp/bootloader-installed")
  
          # test and dry-activate actions are tested further down below
  
      with subtest("services"):
          switch_to_specialisation("${machine}", "")
          # Nothing happens when nothing is changed
  