public OpenConfigConfigOfAssignmentHandler addAssignmentType(
                                               AssignmentTypeEnum assignmentType) {
        modelObject.assignmentType(assignmentType);
        return this;
    }
@Test
    public void testAddAssignmentType() {
        // test Handler
        OpenConfigConfigOfAssignmentHandler config = new OpenConfigConfigOfAssignmentHandler(parent);

        // call addAssignmentType
        config.addAssignmentType(AssignmentTypeEnum.LOGICAL_CHANNEL);

        // expected ModelObject
        DefaultConfig modelObject = new DefaultConfig();
        modelObject.assignmentType(AssignmentTypeEnum.LOGICAL_CHANNEL);

        assertEquals("[NG]addAssignmentType:ModelObject(AssignmentType added) is not an expected one.\n",
                     modelObject, config.getModelObject());
    }