public async Task ExecuteAdd_IncreasesCount()
        {
            var newItemData = new RestItemData();
            var strategy    = new AddToCollectionStrategy();
            await strategy.ExecuteAsync(_collectionMock.Object, new TestEndpointContext(), new ItemBody(newItemData));

            _collectionMock.Verify(c => c.AddAsync(It.IsAny <RestItemData>()), Times.Once);
        }
        public async Task ExecuteAddMany_IncreasesCount()
        {
            var newItemData = new RestItemData();
            var strategy    = new AddToCollectionStrategy();
            var items       = new[] { newItemData, newItemData, newItemData };
            await strategy.ExecuteAsync(_collectionMock.Object, new TestEndpointContext(), new CollectionBody(items, null));

            _collectionMock.Verify(c => c.AddAsync(It.IsAny <RestItemData>()), Times.Exactly(3));
        }