Unit Test WebAPi

Question

 I have this controller and I want to create a unit test for it , I have a small experience with unit testing but now I want to learn it , I'm using Dto here and automapper .

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.Description;
using AutoMapper;
using WebAPiBackend.Dto;
using WebAPiBackend.Models;

namespace WebAPiBackend.Controllers
{
    [AllowAnonymous]
    public class SpecialitiesController : ApiController
    {
        private ApplicationDbContext db = new ApplicationDbContext();

        //// GET: api/Specialities
        //public IQueryable GetSpecialities()
        //{
        //    return db.Specialities;
        //}
        //get with Dto Done
        public IEnumerable GetSpecialities()
        {
            var specQuery = db.Specialities;

            return specQuery
                .ToList()
                .Select(Mapper.Map);
        }
        //DTO
        // GET: api/Specialities/5
        [ResponseType(typeof(Specialities))]
        public IHttpActionResult GetSpecialities(int id)
        {
            //Specialities specialities = db.Specialities.Find(id);
            Specialities specialities = db.Specialities.SingleOrDefault(c => c.SpecialtyId == id);
            if (specialities == null)
            {
                return NotFound();
            }
            return Ok(Mapper.Map(specialities));

            //return Ok(specialities);
        }
        //DTO
        // PUT: api/Specialities/5
        [ResponseType(typeof(void))]
        public IHttpActionResult PutSpecialities(int id, SpecialitiesDto specialitiesDto)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            var speciinDB = db.Specialities.SingleOrDefault(c => c.SpecialtyId == id);
            if (speciinDB == null)
                return NotFound();
            Mapper.Map(specialitiesDto, speciinDB);
            db.SaveChanges();
            return Ok();
        }

        // POST: api/Specialities
        [ResponseType(typeof(Specialities))]
        public IHttpActionResult PostSpecialities(SpecialitiesDto specialitiesDto)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            //addingforDTo
            var specialDTO = Mapper.Map(specialitiesDto);

            db.Specialities.Add(specialDTO);
            db.SaveChanges();
            specialitiesDto.SpecialtyId = specialDTO.SpecialtyId;
            return CreatedAtRoute("DefaultApi", new { id = specialDTO.SpecialtyId }, specialitiesDto);
        }

        // DELETE: api/Specialities/5
        [ResponseType(typeof(Specialities))]
        public IHttpActionResult DeleteSpecialities(int id)
        {
            Specialities specialities = db.Specialities.Find(id);
            if (specialities == null)
            {
                return NotFound();
            }
            //db.Specialities.Remove(specialities);
            specialities.IsDeleted = true;
            db.SaveChanges();
            return Ok(specialities);
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                db.Dispose();
            }
            base.Dispose(disposing);
        }

        private bool SpecialitiesExists(int id)
        {
            return db.Specialities.Count(e => e.SpecialtyId == id) > 0;
        }
    }
}