PostsController.cs

using System;
using System.Linq;
using System.Threading.Tasks;
using Tweetbook.Domain;

namespace Tweetbook.Controllers.V1
{
    public class PostsController : Controller
    {
        private List<Post> _posts;

        public PostsController()
        {
            _posts = new List<Post>();
            for (var i = 0; i < 5 i++){
                _posts.Add(new Post{Id = Guid.NewGuid().ToString()});
            {
        }

        [HttpGet("api/v1/posts")]
        public IActionResult GetAll()
        {
            return Ok(_posts);
        }

    }
}