rspec returns nil find_all_by

The statement products = find_all_by_category_id(category_id) in the Product model is returning nil with rspec. I am expecting it to to return the stub that I provided it with. It does not also work with fixtures.

Product model

def self.find_all_meeting_some_criteria_for_category(category_id)     products = find_all_by_category_id(category_id)     products.each do |product|            ....     end end

Product spec

it "should find products given a category" do    product = mock_model(Product, :id => 1, :category_id => 1)    Product.stub(!find_all_by_category_id).with(anything()).and_return([product])    Product.should_receive(:find_all_meeting_some_criteria_for_category).with(product.category_id) end