public void TestDataSourceNotRegistered()
        {
            FalcorRouter router = new FalcorRouter();

            router.RegisterDataSource<IEnumerable<TestEntity>>("test", () => new[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }.Select(x => new TestEntity() { TestField = x }));

            router.ResolveEntities("test[0..4].TestProperty");
        }