public async Task GetPiesAsync_WhenCalled_ReturnsAllPiesWithCategory()
        {
            // Arrange
            var sut = new PieService(dbContext);

            // Act
            var result = await sut.GetPiesAsync();

            // Assert
            Assert.Equal(pies.Count, result.Count());
            Assert.NotNull(result.First().Category);
            Assert.NotNull(result.Last().Category);
        }
        public async Task GetPiesAsync_WhenCalled_ReturnsAllPiesWithCategory()
        {
            // Act
            List <Pie> pies = null;

            using (var context = new OnlineShopContext(options))
            {
                var sut = new PieService(context);
                pies = (await sut.GetPiesAsync()).ToList();
            }

            // Assert
            Assert.NotNull(pies);
            Assert.Equal(6, pies.Count());
            Assert.NotNull(pies[0].Category);
            Assert.NotNull(pies[1].Category);
            Assert.NotNull(pies[2].Category);
            Assert.NotNull(pies[3].Category);
            Assert.NotNull(pies[4].Category);
            Assert.NotNull(pies[5].Category);
        }