rspec "assigns" and "render"

Hi all,

I'm trying to create some view specs using rspec following the example at
http://rspec.rubyforge.org/documentation/rails/writing/views.html

However, when I put

@person = mock("person")
@person.stub!(:name).and_return 'Joe'
assign[:person] = @person

I get a NameError saying that 'assigns' is not defined.
Similarly, "render '/people/list' " gives me a NoMethodError. Any ideas why
this might be?

Thanks!
Daniel