# Test configuration switching.

import ./make-test-python.nix ({ pkgs, ...} : {
  name = "switch-test";
  meta = with pkgs.lib.maintainers; {
    maintainers = [ gleber das_j ];
  };

  nodes = {
    machine = { pkgs, lib, ... }: {
      users.mutableUsers = false;

      specialisation = rec {
        simpleService.configuration = {
          systemd.services.test = {
            wantedBy = [ "multi-user.target" ];
            serviceConfig = {
              Type = "oneshot";
              RemainAfterExit = true;
              ExecStart = "${pkgs.coreutils}/bin/true";
              ExecReload = "${pkgs.coreutils}/bin/true";
            };
          };
        };

        simpleServiceModified.configuration = {
          imports = [ simpleService.configuration ];
          systemd.services.test.serviceConfig.X-Test = true;
        };

        simpleServiceNostop.configuration = {
          imports = [ simpleService.configuration ];
          systemd.services.test.stopIfChanged = false;
        };

        simpleServiceReload.configuration = {
          imports = [ simpleService.configuration ];
          systemd.services.test = {
            reloadIfChanged = true;
            serviceConfig.ExecReload = "${pkgs.coreutils}/bin/true";
          };
        };

        simpleServiceNorestart.configuration = {
          imports = [ simpleService.configuration ];
          systemd.services.test.restartIfChanged = false;
        };

        simpleServiceFailing.configuration = {
          imports = [ simpleServiceModified.configuration ];
          systemd.services.test.serviceConfig.ExecStart = lib.mkForce "${pkgs.coreutils}/bin/false";
        };

        autorestartService.configuration = {
          # A service that immediately goes into restarting (but without failing)
          systemd.services.autorestart = {
            wantedBy = [ "multi-user.target" ];
            serviceConfig = {
              Type = "simple";
              Restart = "always";
              RestartSec = "20y"; # Should be long enough
              ExecStart = "${pkgs.coreutils}/bin/true";
            };
          };
        };

        autorestartServiceFailing.configuration = {
          imports = [ autorestartService.configuration ];
          systemd.services.autorestart.serviceConfig = {
            ExecStart = lib.mkForce "${pkgs.coreutils}/bin/false";
          };
        };

        simpleServiceWithExtraSection.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.packages = [ (pkgs.writeTextFile {
            name = "systemd-extra-section";
            destination = "/etc/systemd/system/test.service";
            text = ''
              [X-Test]
              X-Test-Value=a
            '';
          }) ];
        };

        simpleServiceWithExtraSectionOtherName.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.packages = [ (pkgs.writeTextFile {
            name = "systemd-extra-section";
            destination = "/etc/systemd/system/test.service";
            text = ''
              [X-Test2]
              X-Test-Value=a
            '';
          }) ];
        };

        simpleServiceWithInstallSection.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.packages = [ (pkgs.writeTextFile {
            name = "systemd-extra-section";
            destination = "/etc/systemd/system/test.service";
            text = ''
              [Install]
              WantedBy=multi-user.target
            '';
          }) ];
        };

        simpleServiceWithExtraKey.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.services.test.serviceConfig."X-Test" = "test";
        };

        simpleServiceWithExtraKeyOtherValue.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.services.test.serviceConfig."X-Test" = "test2";
        };

        simpleServiceWithExtraKeyOtherName.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.services.test.serviceConfig."X-Test2" = "test";
        };

        simpleServiceReloadTrigger.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.services.test.reloadTriggers = [ "/dev/null" ];
        };

        simpleServiceReloadTriggerModified.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.services.test.reloadTriggers = [ "/dev/zero" ];
        };

        simpleServiceReloadTriggerModifiedAndSomethingElse.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.services.test = {
            reloadTriggers = [ "/dev/zero" ];
            serviceConfig."X-Test" = "test";
          };
        };

        simpleServiceReloadTriggerModifiedSomethingElse.configuration = {
          imports = [ simpleServiceNostop.configuration ];
          systemd.services.test.serviceConfig."X-Test" = "test";
        };

        restart-and-reload-by-activation-script.configuration = {
          systemd.services = rec {
            simple-service = {
              # No wantedBy so we can check if the activation script restart triggers them
              serviceConfig = {
                Type = "oneshot";
                RemainAfterExit = true;
                ExecStart = "${pkgs.coreutils}/bin/true";
                ExecReload = "${pkgs.coreutils}/bin/true";
              };
            };

            simple-restart-service = simple-service // {
              stopIfChanged = false;
            };

            simple-reload-service = simple-service // {
              reloadIfChanged = true;
            };

            no-restart-service = simple-service // {
              restartIfChanged = false;
            };

            reload-triggers = simple-service // {
              wantedBy = [ "multi-user.target" ];
            };

            reload-triggers-and-restart-by-as = simple-service;

            reload-triggers-and-restart = simple-service // {
              stopIfChanged = false; # easier to check for this
              wantedBy = [ "multi-user.target" ];
            };
          };

          system.activationScripts.restart-and-reload-test = {
            supportsDryActivation = true;
            deps = [];
            text = ''
              if [ "$NIXOS_ACTION" = dry-activate ]; then
                f=/run/nixos/dry-activation-restart-list
                g=/run/nixos/dry-activation-reload-list
              else
                f=/run/nixos/activation-restart-list
                g=/run/nixos/activation-reload-list
              fi
              cat <<EOF >> "$f"
              simple-service.service
              simple-restart-service.service
              simple-reload-service.service
              no-restart-service.service
              reload-triggers-and-restart-by-as.service
              EOF

              cat <<EOF >> "$g"
              reload-triggers.service
              reload-triggers-and-restart-by-as.service
              reload-triggers-and-restart.service
              EOF
            '';
          };
        };

        restart-and-reload-by-activation-script-modified.configuration = {
          imports = [ restart-and-reload-by-activation-script.configuration ];
          systemd.services.reload-triggers-and-restart.serviceConfig.X-Modified = "test";
        };

        mount.configuration = {
          systemd.mounts = [
            {
              description = "Testmount";
              what = "tmpfs";
              type = "tmpfs";
              where = "/testmount";
              options = "size=1M";
              wantedBy = [ "local-fs.target" ];
            }
          ];
        };

        mountModified.configuration = {
          systemd.mounts = [
            {
              description = "Testmount";
              what = "tmpfs";
              type = "tmpfs";
              where = "/testmount";
              options = "size=10M";
              wantedBy = [ "local-fs.target" ];
            }
          ];
        };

        timer.configuration = {
          systemd.timers.test-timer = {
            wantedBy = [ "timers.target" ];
            timerConfig.OnCalendar = "@1395716396"; # chosen by fair dice roll
          };
          systemd.services.test-timer = {
            serviceConfig = {
              Type = "oneshot";
              ExecStart = "${pkgs.coreutils}/bin/true";
            };
          };
        };

        timerModified.configuration = {
          imports = [ timer.configuration ];
          systemd.timers.test-timer.timerConfig.OnCalendar = lib.mkForce "Fri 2012-11-23 16:00:00";
        };

        path.configuration = {
          systemd.paths.test-watch = {
            wantedBy = [ "paths.target" ];
            pathConfig.PathExists = "/testpath";
          };
          systemd.services.test-watch = {
            serviceConfig = {
              Type = "oneshot";
              ExecStart = "${pkgs.coreutils}/bin/touch /testpath-modified";
            };
          };
        };

        pathModified.configuration = {
          imports = [ path.configuration ];
          systemd.paths.test-watch.pathConfig.PathExists = lib.mkForce "/testpath2";
        };

        slice.configuration = {
          systemd.slices.testslice.sliceConfig.MemoryMax = "1"; # don't allow memory allocation
          systemd.services.testservice = {
            serviceConfig = {
              Type = "oneshot";
              RemainAfterExit = true;
              ExecStart = "${pkgs.coreutils}/bin/true";
              Slice = "testslice.slice";
            };
          };
        };

        sliceModified.configuration = {
          imports = [ slice.configuration ];
          systemd.slices.testslice.sliceConfig.MemoryMax = lib.mkForce null;
        };
      };
    };

    other = {
      users.mutableUsers = true;
    };
  };

  testScript = { nodes, ... }: let
    originalSystem = nodes.machine.config.system.build.toplevel;
    otherSystem = nodes.other.config.system.build.toplevel;
    machine = nodes.machine.config.system.build.toplevel;

    # Ensures failures pass through using pipefail, otherwise failing to
    # switch-to-configuration is hidden by the success of `tee`.
    stderrRunner = pkgs.writeScript "stderr-runner" ''
      #! ${pkgs.runtimeShell}
      set -e
      set -o pipefail
      exec env -i "$@" | tee /dev/stderr
    '';
  in /* python */ ''
    def switch_to_specialisation(system, name, action="test", fail=False):
        if name == "":
            stc = f"{system}/bin/switch-to-configuration"
        else:
            stc = f"{system}/specialisation/{name}/bin/switch-to-configuration"
        out = machine.fail(f"{stc} {action} 2>&1") if fail \
            else machine.succeed(f"{stc} {action} 2>&1")
        assert_lacks(out, "switch-to-configuration line")  # Perl warnings
        return out

    def assert_contains(haystack, needle):
        if needle not in haystack:
            print("The haystack that will cause the following exception is:")
            print("---")
            print(haystack)
            print("---")
            raise Exception(f"Expected string '{needle}' was not found")

    def assert_lacks(haystack, needle):
        if needle in haystack:
            print("The haystack that will cause the following exception is:")
            print("---")
            print(haystack, end="")
            print("---")
            raise Exception(f"Unexpected string '{needle}' was found")


    machine.wait_for_unit("multi-user.target")

    machine.succeed(
        "${stderrRunner} ${originalSystem}/bin/switch-to-configuration test"
    )
    machine.succeed(
        "${stderrRunner} ${otherSystem}/bin/switch-to-configuration test"
    )

    with subtest("services"):
        switch_to_specialisation("${machine}", "")
        # Nothing happens when nothing is changed
        out = switch_to_specialisation("${machine}", "")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # 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
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_contains(out, "the following new units were started: test.service\n")
        assert_lacks(out, "as well:")

        # Not changing anything doesn't do anything
        out = switch_to_specialisation("${machine}", "simpleService")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Restart the simple service
        out = switch_to_specialisation("${machine}", "simpleServiceModified")
        assert_contains(out, "stopping the following units: test.service\n")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_contains(out, "\nstarting the following units: test.service\n")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Restart the service with stopIfChanged=false
        out = switch_to_specialisation("${machine}", "simpleServiceNostop")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Reload the service with reloadIfChanged=true
        out = switch_to_specialisation("${machine}", "simpleServiceReload")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_contains(out, "reloading the following units: test.service\n")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Nothing happens when restartIfChanged=false
        out = switch_to_specialisation("${machine}", "simpleServiceNorestart")
        assert_lacks(out, "stopping the following units:")
        assert_contains(out, "NOT restarting the following changed units: test.service\n")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Dry mode shows different messages
        out = switch_to_specialisation("${machine}", "simpleService", action="dry-activate")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")
        assert_contains(out, "would start the following units: test.service\n")

    with subtest("failing units"):
        # Let the simple service fail
        switch_to_specialisation("${machine}", "simpleServiceModified")
        out = switch_to_specialisation("${machine}", "simpleServiceFailing", fail=True)
        assert_contains(out, "stopping the following units: test.service\n")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_contains(out, "\nstarting the following units: test.service\n")
        assert_lacks(out, "the following new units were started:")
        assert_contains(out, "warning: the following units failed: test.service\n")
        assert_contains(out, "Main PID:")  # output of systemctl
        assert_lacks(out, "as well:")

        # A unit that gets into autorestart without failing is not treated as failed
        out = switch_to_specialisation("${machine}", "autorestartService")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_contains(out, "the following new units were started: autorestart.service\n")
        assert_lacks(out, "as well:")
        machine.systemctl('stop autorestart.service')  # cancel the 20y timer

        # Switching to the same system should do nothing (especially not treat the unit as failed)
        out = switch_to_specialisation("${machine}", "autorestartService")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_contains(out, "the following new units were started: autorestart.service\n")
        assert_lacks(out, "as well:")
        machine.systemctl('stop autorestart.service')  # cancel the 20y timer

        # If systemd thinks the unit has failed and is in autorestart, we should show it as failed
        out = switch_to_specialisation("${machine}", "autorestartServiceFailing", fail=True)
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_contains(out, "warning: the following units failed: autorestart.service\n")
        assert_contains(out, "Main PID:")  # output of systemctl
        assert_lacks(out, "as well:")

    with subtest("unit file parser"):
        # Switch to a well-known state
        switch_to_specialisation("${machine}", "simpleServiceNostop")

        # Add a section
        out = switch_to_specialisation("${machine}", "simpleServiceWithExtraSection")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Rename it
        out = switch_to_specialisation("${machine}", "simpleServiceWithExtraSectionOtherName")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Remove it
        out = switch_to_specialisation("${machine}", "simpleServiceNostop")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # [Install] section is ignored
        out = switch_to_specialisation("${machine}", "simpleServiceWithInstallSection")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Add a key
        out = switch_to_specialisation("${machine}", "simpleServiceWithExtraKey")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Change its value
        out = switch_to_specialisation("${machine}", "simpleServiceWithExtraKeyOtherValue")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Rename it
        out = switch_to_specialisation("${machine}", "simpleServiceWithExtraKeyOtherName")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Remove it
        out = switch_to_specialisation("${machine}", "simpleServiceNostop")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Add a reload trigger
        out = switch_to_specialisation("${machine}", "simpleServiceReloadTrigger")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_contains(out, "reloading the following units: test.service\n")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Modify the reload trigger
        out = switch_to_specialisation("${machine}", "simpleServiceReloadTriggerModified")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_contains(out, "reloading the following units: test.service\n")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Modify the reload trigger and something else
        out = switch_to_specialisation("${machine}", "simpleServiceReloadTriggerModifiedAndSomethingElse")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "\nrestarting the following units: test.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

        # Remove the reload trigger
        out = switch_to_specialisation("${machine}", "simpleServiceReloadTriggerModifiedSomethingElse")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")

    with subtest("restart and reload by activation script"):
        switch_to_specialisation("${machine}", "simpleServiceNorestart")
        out = switch_to_specialisation("${machine}", "restart-and-reload-by-activation-script")
        assert_contains(out, "stopping the following units: test.service\n")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "restarting the following units:")
        assert_contains(out, "\nstarting the following units: no-restart-service.service, reload-triggers-and-restart-by-as.service, simple-reload-service.service, simple-restart-service.service, simple-service.service\n")
        assert_lacks(out, "as well:")
        # Switch to the same system where the example services get restarted
        # and reloaded by the activation script
        out = switch_to_specialisation("${machine}", "restart-and-reload-by-activation-script")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_contains(out, "reloading the following units: reload-triggers-and-restart.service, reload-triggers.service, simple-reload-service.service\n")
        assert_contains(out, "restarting the following units: reload-triggers-and-restart-by-as.service, simple-restart-service.service, simple-service.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "as well:")
        # Switch to the same system and see if the service gets restarted when it's modified
        # while the fact that it's supposed to be reloaded by the activation script is ignored.
        out = switch_to_specialisation("${machine}", "restart-and-reload-by-activation-script-modified")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_contains(out, "reloading the following units: reload-triggers.service, simple-reload-service.service\n")
        assert_contains(out, "restarting the following units: reload-triggers-and-restart-by-as.service, reload-triggers-and-restart.service, simple-restart-service.service, simple-service.service\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "as well:")
        # The same, but in dry mode
        out = switch_to_specialisation("${machine}", "restart-and-reload-by-activation-script", action="dry-activate")
        assert_lacks(out, "would stop the following units:")
        assert_lacks(out, "would NOT stop the following changed units:")
        assert_contains(out, "would reload the following units: reload-triggers.service, simple-reload-service.service\n")
        assert_contains(out, "would restart the following units: reload-triggers-and-restart-by-as.service, reload-triggers-and-restart.service, simple-restart-service.service, simple-service.service\n")
        assert_lacks(out, "\nwould start the following units:")
        assert_lacks(out, "as well:")

    with subtest("mounts"):
        switch_to_specialisation("${machine}", "mount")
        out = machine.succeed("mount | grep 'on /testmount'")
        assert_contains(out, "size=1024k")
        out = switch_to_specialisation("${machine}", "mountModified")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_contains(out, "reloading the following units: testmount.mount\n")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")
        # It changed
        out = machine.succeed("mount | grep 'on /testmount'")
        assert_contains(out, "size=10240k")

    with subtest("timers"):
        switch_to_specialisation("${machine}", "timer")
        out = machine.succeed("systemctl show test-timer.timer")
        assert_contains(out, "OnCalendar=2014-03-25 02:59:56 UTC")
        out = switch_to_specialisation("${machine}", "timerModified")
        assert_lacks(out, "stopping the following units:")
        assert_lacks(out, "reloading the following units:")
        assert_contains(out, "restarting the following units: test-timer.timer\n")
        assert_lacks(out, "\nstarting the following units:")
        assert_lacks(out, "the following new units were started:")
        assert_lacks(out, "as well:")
        # It changed
        out = machine.succeed("systemctl show test-timer.timer")
        assert_contains(out, "OnCalendar=Fri 2012-11-23 16:00:00")

    with subtest("paths"):
        out = switch_to_specialisation("${machine}", "path")
        assert_contains(out, "stopping the following units: test-timer.timer\n")
        assert_lacks(out, "NOT restarting the following changed units:")
        assert_lacks(out, "reloading the following units:")
        assert_lacks(out, "\nrestarting the following units:")
        assert_lacks(out, "\nstarting the following units:")
        assert_contains(out, "the following new units were started: test-watch.path")
        assert_lacks(out, "as well:")
        machine.fail("test -f /testpath-modified")

        # touch the file, unit should be triggered
        machine.succeed("touch /testpath")
        machine.wait_until_succeeds("test -f /testpath-modified")
        machine.succeed("rm /testpath /testpath-modified")
        switch_to_specialisation("${machine}", "pathModified")
        machine.succeed("touch /testpath")
        machine.fail("test -f /testpath-modified")
        machine.succeed("touch /testpath2")
        machine.wait_until_succeeds("test -f /testpath-modified")

    # This test ensures that changes to slice configuration get applied.
    # We test this by having a slice that allows no memory allocation at
    # all and starting a service within it. If the service crashes, the slice
    # is applied and if we modify the slice to allow memory allocation, the
    # service should successfully start.
    with subtest("slices"):
        machine.succeed("echo 0 > /proc/sys/vm/panic_on_oom")  # allow OOMing
        out = switch_to_specialisation("${machine}", "slice")
        machine.fail("systemctl start testservice.service")
        out = switch_to_specialisation("${machine}", "sliceModified")
        machine.succeed("systemctl start testservice.service")
        machine.succeed("echo 1 > /proc/sys/vm/panic_on_oom")  # disallow OOMing
  '';
})