"Mock#to_hash should return Hash"

My Rails 3 application has a Product resource.

In my ProductsController specs, the generated tests are making sure that I redirect to a product's url afer updating it.

The following code errors:

#inside ProductsController spec
def mock_product(stubs={})
  (@mock_product ||= mock_model(Product).as_null_object).tap do |product|
    product.stub(stubs) unless stubs.empty?
  end
end

it "should do something" do 
  product_url(mock_product)
end

The error is:

TypeError: RSpec::Mocks::Mock#to_hash should return Hash

My mock_model is defined as_null_object (which means that it will respond to all messages, except those stubbed, by returning itself.

So, rails routing helpers (like product_url(product)) first converst the product to a hash, and uses the product['id'] to generate the route.

Since my mock_product didn't stub to_hash, the "as_null_object" behavior took precedence

irb > mock_product
=> #<Product:0x..fdb3b6176 @name="Product_1028">
irb > mock_product.to_hash
=> #<Product:0x..fdb3b6176 @name="Product_1028">

My solution was to stub to_hash:

irb > mock_product(:to_hash => {:id => 1 }).to_hash
=> {:id=>1}

Should this be included in the mock_product model by default?