[Rails] Test params

Hi,

In my RESTful implementation, :new shows a form for @link . When a
user clicks on Create, the value of @link is posted to :create through
params. How do I test the value of params and that :create actually
uses these value to create a new link.

Right now I test :create by by using a link fixture but I want to
actually use the value of params passed in through :new. I suspect
that an integration test is needed but how can I do this?

Thanks.

Vincent.