public void GetByCityId_ShouldReturnCorrectAd()
{
System.Guid guid = new Guid("c42ae80e-346f-4a4d-b4d9-2834c762a27f"); //city1
var response = controller.GetByCityId(guid);
Assert.AreEqual(HttpStatusCode.OK, response.StatusCode);
var ad = response.Content.ReadAsAsync <IEnumerable <Ad> >().Result;
Assert.AreEqual(ads.Where(c => c.Value.CityId == guid).Count(), ad.Count());
}