{
  clan-core,
  lib,
}:
# TODO: TEST: define a clan without machines
{
  test_simple =
    let
      eval = clan-core.clanLib.clan {
        exports."///".foo = lib.mkForce eval.config.exports."///".bar;

        directory = ./.;
        self = {
          clan = eval.config;
          inputs = { };
        };

        machines.jon = { };
        machines.sara = { };

        exportsModule =
          { lib, ... }:
          {
            options.foo = lib.mkOption {
              type = lib.types.number;
              default = 0;
            };
            options.bar = lib.mkOption {
              type = lib.types.number;
              default = 0;
            };
          };

        ####### Service module "A"
        modules.service-A =
          { ... }:
          {
            # config.exports
            manifest.name = "A";

            roles.default = {
              # TODO: Remove automapping
              # Currently exports are automapped
              # scopes "/service=A/instance=hello/role=default/machine=jon"
              # perInstance.exports.foo = 7;

              # New style:
              # Explizit scope
              # perInstance.exports."service=A/instance=hello/role=default/machine=jon".foo = 7;
              perInstance =
                { instanceName, machine, exports, ... }:
                {
                  exports."A/${instanceName}/default/${machine.name}" = {
                    foo = 7;
                    # define export depending on B
                    bar = exports."B/B/default/${machine.name}".foo + 35;
                  };
                  # exports."A/${instanceName}/default/${machine.name}".

                  # default behavior
                  # exports = scope.mkExports { foo = 7; };

                  # We want to export things for different scopes from this scope;
                  # If this scope is used.
                  #
                  # Explicit scope; different from the function scope above
                  # exports = clanLib.scopedExport {
                  #   # Different role export
                  #   role = "peer";
                  #   serviceName = config.manifest.name;
                  #   inherit instanceName machineName;
                  # } { foo = 7; };
                };
            };

            perMachine =
              { ... }:
              {
                #
                # exports = scope.mkExports { foo = 7; };
                # exports."A///${machine.name}".foo = 42;
                # exports."B///".foo = 42;
              };

            # scope "/service=A/instance=??/role=??/machine=jon"
            # perMachine.exports.foo = 42;

            # scope "/service=A/instance=??/role=??/machine=??"
            # exports."///".foo = 10;
          };
        ####### Service module "A"
        modules.service-B =
          { exports, ... }:
          {
            # config.exports
            manifest.name = "B";

            roles.default = {
              # TODO: Remove automapping
              # Currently exports are automapped
              # scopes "/service=A/instance=hello/role=default/machine=jon"
              # perInstance.exports.foo = 7;

              # New style:
              # Explizit scope
              # perInstance.exports."service=A/instance=hello/role=default/machine=jon".foo = 7;
              perInstance =
                { instanceName, machine, ... }:
                {
                  # TODO: Test non-existing scope
                  # define export depending on A
                  exports."B/${instanceName}/default/${machine.name}".foo = exports."///".foo + exports."A/A/default/${machine.name}".foo;
                  # exports."B/B/default/jon".foo = exports."A/A/default/jon".foo;

                  # default behavior
                  # exports = scope.mkExports { foo = 7; };

                  # We want to export things for different scopes from this scope;
                  # If this scope is used.
                  #
                  # Explicit scope; different from the function scope above
                  # exports = clanLib.scopedExport {
                  #   # Different role export
                  #   role = "peer";
                  #   serviceName = config.manifest.name;
                  #   inherit instanceName machineName;
                  # } { foo = 7; };
                };
            };

            perMachine =
              { ... }:
              {
                # exports = scope.mkExports { foo = 7; };
                # exports."A///${machine.name}".foo = 42;
                # exports."B///".foo = 42;
              };

            # scope "/service=A/instance=??/role=??/machine=jon"
            # perMachine.exports.foo = 42;

            # scope "/service=A/instance=??/role=??/machine=??"
            exports."///".foo = 10;
          };
        #######

        inventory = {
          instances.A = {
            module.name = "service-A";
            module.input = "self";
            roles.default.tags = [ "all" ];
          };
          instances.B = {
            module.name = "service-B";
            module.input = "self";
            roles.default.tags = [ "all" ];
          };
        };
        # <- inventory
        #
        # -> exports
        /**
          Current state
          {
            instances = {
              hello = { networking = null; };
            };
            machines = {
              jon = { networking = null; };
            };
          }
        */
        /**
          Target state: (Flat attribute set)

          tdlr;

          # roles / instance level definitions may not exist on their own
          # role and instance names are completely arbitrary.
          # For example what does it mean: this is a export for all "peer" roles of all service-instances? That would be magic on the roleName.
          # Or exports for all instances with name "ifoo" ? That would be magic on the instanceName.

          # Practical combinations
          # always include either the service name or the machine name

          exports = {
            # Clan level (1)
            "///" networks generators

            # Service anchored (8) : min 1 instance is needed ; machines may not exist
            "A///" <- service specific
            "A/instance//" <- instance of a service
            "A//peer/" <- role of a service
            "A/instance/peer/" <- instance+role of a service
            "A///machine" <- machine of a service
            "A/instance//machine" <- machine + instance of a service
            "A//role/machine" <- machine + role of a service
            "A/instance/role/machine" <- machine + role + instance of a service

            # Machine anchored (1 or 2)
            "///jon" <- this machine
            "A///jon" <- role on a machine (dupped with service anchored)

            # Unpractical; probably not needed (5)
            "//peer/jon" <- role on a machine
            "/instance//jon" <- role on a machine
            "/instance//" <- instance: All "foo" instances everywhere?
            "//role/" <- role: All "peer" roles everywhere?
            "/instance/role/" <- instance role: Applies to all services, whose instance name has "ifoo" and role is "peer" (double magic)

            # TODO: lazyattrs poc
          }
        */
      };
    in
    {
      inherit eval;
      expr = eval;
      expected = 42;
    };
}