Rspec test cannot be passed when render partial in layout

I have a problem stuck me couples of days, could anyone help me?
Thanks very much.
The problem is that rspec test cannot be passed when the layout
contains :partial, once
i removed the :partial, the rspec test passed successfully. I could
not find out the reason.
Below is my code:
application.html.erb

<%= render :partial => 'shared/header' %>
<%= yield %>
<%= render :partial => 'shared/footer' %>

users_controller_spec.rb
describe UsersController do
describe “Requesting /forgot_password using GET” do
it “should be successful” do
get :forgot_password
end
end
end