Use the assigns method (*note: assigns is now deprecated. See bottom of my answer for info):
it "assigns the @widget"
expect(assigns(:widget)).not_to be_nil
end
Of course, you can inspect widget as you’d like, but without seeing what @widget is from your provided controller code, I just checked if it was nil
If you’re wanting to puts the widget, like in your example, just print it with assigns
puts assigns(:widget)
EDIT: assigns is now deprecated (see: https://apidock.com/rails/ActionController/TestProcess/assigns)
If you want to continue using assigns you will need to install the rails-controller-testing gem.
Otherwise, you could use what rails-controller-testing gem uses internally: @controller.view_assigns[]