Build an API

using GoodBooksAPI.DataAccess;
using GoodBooksAPI.Models;
using Microsoft.AspNetCore.Mvc.Testing;
using Microsoft.EntityFrameworkCore;
using Newtonsoft.Json.Serialization;
using Newtonsoft.Json;
using System.Reflection;
using System.Runtime.Intrinsics.X86;

namespace GoodBooksEndpointTests
{
    public class BookCrudEndpointTests : IClassFixture<WebApplicationFactory<Program>>
    {
        private readonly WebApplicationFactory<Program> _factory;

        public BookCrudEndpointTests(WebApplicationFactory<Program> factory)
        {
            _factory = factory;
        }

        [Fact]
        public async void GetBooks_ReturnsListOfBooks()
        {
            Book book1 = new Book { Title = "Dune", Description = "Sand Monsters" };
            Book book2 = new Book { Title = "Wool", Description = "Human Monsters" };
            List<Book> books = new() { book1, book2 };

            GoodBooksApiContext context = GetDbContext();
            HttpClient client = _factory.CreateClient();
            context.Books.AddRange(books);
            context.SaveChanges();

            HttpResponseMessage response = await client.GetAsync("/api/books");
            string content = await response.Content.ReadAsStringAsync();

            // The method ObjectToJson is defined below
            string expected = ObjectToJson(books);

            response.EnsureSuccessStatusCode();
            Assert.Equal(expected, content);

        }

        // This method helps us create an expected value. We can use the Newtonsoft JSON serializer to build the string that we expect.  Without this helper method, we would need to manually create the expected JSON string.
        private string ObjectToJson(object obj)
        {
            DefaultContractResolver contractResolver = new DefaultContractResolver
            {
                NamingStrategy = new CamelCaseNamingStrategy()
            };

            string json = JsonConvert.SerializeObject(obj, new JsonSerializerSettings
            {
                ContractResolver = contractResolver
            });

            return json;
        }

        private GoodBooksApiContext GetDbContext()
        {
            var optionsBuilder = new DbContextOptionsBuilder<GoodBooksApiContext>();
            optionsBuilder.UseInMemoryDatabase("TestDatabase");

            var context = new GoodBooksApiContext(optionsBuilder.Options);
            context.Database.EnsureDeleted();
            context.Database.EnsureCreated();

            return context;
        }
    }
}

using GoodBooksAPI.DataAccess;
using GoodBooksAPI.Models;
using Microsoft.AspNetCore.Mvc;

namespace GoodBooksAPI.Controllers
{
    // This will be the default route - controller gets replaced with the name of the controller.
    // "/api/books"
    [Route("/api/[controller]")]
    [ApiController]
    public class BooksController : ControllerBase
    {
        private GoodBooksApiContext _context;

        public BooksController(GoodBooksApiContext context)
        {
            _context = context;
        }

        // GET "/api/books"
        [HttpGet]
        public ActionResult GetBooks()
        {
            List<Book> books = _context.Books.ToList();

            // We could manually set the response code like this:
            //Response.StatusCode = 200;

            // API endpoints should return JSON, we are creating a new JSON result with our list of books.
            return new JsonResult(books);
        }
    }
}

[Fact]
public async void PostBook_CreatesBookInDb()
{
    // Create fresh database
    GoodBooksApiContext context = GetDbContext();

    // Set up and send the request
    HttpClient client = _factory.CreateClient();
    var jsonString = "{\"Title\":\"Lamb's Wool\", \"Description\":\"Super Itchy\"}";
    var requestContent = new StringContent(jsonString, Encoding.UTF8, "application/json");
    var response = await client.PostAsync("/api/books", requestContent);

    // Get the first (and should be only) book from the db
    var newBook = context.Books.First();

    Assert.Equal("Created", response.StatusCode.ToString());
    Assert.Equal(201, (int)response.StatusCode);
    Assert.Equal("Lamb's Wool", newBook.Title);
}

[HttpPost]
public ActionResult CreateBook(Book book)
{
    if (!ModelState.IsValid)
    {
        Response.StatusCode = 400;
        return;
    }
    _context.Books.Add(book);
    _context.SaveChanges();

    var savedBook = _context.Books.Last();

    Response.StatusCode = 201;
    return new JsonResult(savedBook);
}