public async Task AddFirstOne()
        {
            using var mocker = AutoMock.GetStrict();

            await using var handler = mocker.Create <AddItemToCartEventHandler>();
            var state = new CartState();
            var evt   = new AddItemToCartEvent
            {
                SkuId = "skuId1",
                Count = 10
            };
            await handler.HandleEvent(state, evt, default);

            state.Items.Count.Should().Be(1);
            var(key, value) = state.Items.Single();
            key.Should().Be(evt.SkuId);
            value.Should().Be(evt.Count);
        }
        public async Task AddOneKeyFound()
        {
            using var mocker = AutoMock.GetStrict();

            await using var handler = mocker.Create <AddItemToCartEventHandler>();
            const string skuId = "skuId1";
            var          state = new CartState
            {
                Items = new Dictionary <string, int>
                {
                    { skuId, 60 }
                }
            };
            var evt = new AddItemToCartEvent
            {
                SkuId = skuId,
                Count = 10
            };
            await handler.HandleEvent(state, evt, default);

            var(key, value) = state.Items.Single();
            key.Should().Be(skuId);
            value.Should().Be(70);
        }