Demo/Program.cs

using Posechaemost.Data.Repository;
using Posechaemost.Domain.UseCase;
using Posechaemost.UI;
using Microsoft.Extensions.DependencyInjection;
using System.Text.RegularExpressions;

IServiceCollection services = new ServiceCollection();

services
    .AddSingleton<IGroupRepository, GroupRepositoryImpl>()
    .AddSingleton<UserUseCase>();

var serviceProvider = services.BuildServiceProvider();

GroupRepositoryImpl groupRepositoryImpl = new GroupRepositoryImpl();
UserUseCase userUseCase = serviceProvider.GetService<UserUseCase>();
GroupUseCase groupUseCase = new GroupUseCase(groupRepositoryImpl);

MainMenuUI mainMenuUI = new MainMenuUI(userUseCase, groupUseCase);