Registering IDbCommand and autowiring and testing

builder.Services.AddScoped<IDbConnection>(
    _ => new NpgsqlConnection(builder.Configuration.GetConnectionString("DefaultConnection"))
);
builder.Services.AddScoped<RegionRepository>();

            var conn = services.FirstOrDefault(descriptor => descriptor.ServiceType == typeof(IDbConnection));
            if (conn is null)
            {
                throw new Exception("NpgsqlConnection is not registered.");
            }
            services.Remove(conn);
            services.AddScoped<IDbConnection>(
                _ => new NpgsqlConnection(_postgreSqlContainer.GetConnectionString())
            );