MVC moq with repository that uses lambda expression - asp.net-mvc-3

Question

I have a controller method that acceses a repository method which has lambda expression as parameter:
// GET: /Product/
public ViewResult List(string category, int page = 1) {
ProductsListViewModel productsListViewModel = new ProductsListViewModel {
Products = _repository.GetByPage(q => q.Category == category || category == null, page, PageSize),
PagingInfo = new PagingInfo {
CurrentPage = page,
ItemsPerPage = PageSize,
TotalItems = _repository.Get(q=>q.Category==category || category==null).Count()
},
CurrentCategory = category
};
return View(productsListViewModel);
}
In my unit test, when controller invokes the repository method, returned object("result" variable) is always null, do you have any idea about this situation?
public void Can_Paginate() {
//Arrange
//Create mock repository
Mock<IProductRepository> mock = new Mock<IProductRepository>();
mock.Setup(q => q.GetByPage(c=>c.Category=="C1",1,3)).Returns(new List<Product>
{
new Product {Id = 1, Name = "P1", Category = "C1"},
new Product {Id = 2, Name = "P2", Category = "C1"},
new Product {Id = 3, Name = "P3", Category = "C1"}
});
mock.Setup(q => q.Get(c => c.Category == "C1")).Returns(new List<Product>
{
new Product {Id = 1, Name = "P1", Category = "C1"},
new Product {Id = 2, Name = "P2", Category = "C1"},
new Product {Id = 3, Name = "P3", Category = "C1"}
});
//Create a controller and make page size 3 items
ProductController controller = new ProductController(mock.Object);
controller.PageSize = 3;
//Action
ProductsListViewModel result = (ProductsListViewModel) controller.List("C1", 1).Model;
//Assert
Assert.IsTrue(result.Products.Count()==3);
}
Thanks

Answer 1

Just had quick look at the moq wiki and it had an example of matching Func<int>
as a parameter. So to match an argument of Func<string> you would write something like this:
mock.Setup(q => q.GetByPage(It.Is<string>(c=>c.Category=="C1"),1,3)).Returns...