public void CreateService_UnwrapsFilterFactory()
        {
            // Arrange
            var serviceProvider = new ServiceCollection()
                                  .AddSingleton(new TestFilterFactory())
                                  .BuildServiceProvider();

            var serviceFilter = new ServiceFilterAttribute(typeof(TestFilterFactory));

            // Act
            var filter = serviceFilter.CreateInstance(serviceProvider);

            // Assert
            Assert.IsType <TestFilter>(filter);
        }
        public void CreateService_GetsFilterFromServiceProvider()
        {
            // Arrange
            var expected        = new TestFilter();
            var serviceProvider = new ServiceCollection()
                                  .AddSingleton(expected)
                                  .BuildServiceProvider();

            var serviceFilter = new ServiceFilterAttribute(typeof(TestFilter));

            // Act
            var filter = serviceFilter.CreateInstance(serviceProvider);

            // Assert
            Assert.Same(expected, filter);
        }