public void DeleteAllAsync_Success()
        {
            // Arrange
            var items = new List <Car>()
            {
                new Car()
                {
                    Id = 1, Model = "modelTest", Productor = "ProductorTest", Year = 1970
                },
                new Car()
                {
                    Id = 2, Model = "modelTest1", Productor = "ProductorTest1", Year = 1970
                },
                new Car()
                {
                    Id = 3, Model = "modelTest2", Productor = "ProductorTest2", Year = 1970
                }
            };

            items.ForEach(x => Task.FromResult(db.AddItemAsync(x).ConfigureAwait(true)));
            Assert.AreEqual(items.Count, db.GetItemsAsync().Result.Count);

            // Act
            Task.FromResult(db.DeleteAllAsync());

            // Assert
            Assert.AreEqual(0, db.GetItemsAsync().Result.Count);
        }