public void GetUrlTest(string id)
        {
            // Arrange.
            IDataAccess       demoDataAccess    = new DemoDataAccess();
            IServersManager   serversManager    = new ServersManager(demoDataAccess);
            ServersController serversController = new ServersController(serversManager);

            // Act.
            ActionResult <Server> actionResult = serversController.GetUrl(id);

            // Assert.
            ObjectResult expectedResult;
            Server       server = demoDataAccess.GetServerByIdOfFlight(id);

            if (server != null)
            {
                expectedResult = new OkObjectResult(server);
            }
            else
            {
                expectedResult = new NotFoundObjectResult(id);
            }
            Assert.IsInstanceOfType(actionResult.Result, expectedResult.GetType());
        }