Faster Tests - How to Decouple Rails 4 Controllers? - ruby-on-rails-3

Question

Why this Matters
Testing Ruby methods isolated from the Rails framework == dramatically shorter testing times.
The Problem
How do I correctly decouple the Rails 4 controllers?
Where things are now
Presently, this is my rspec error:
NameError:
undefined local variable or method `response'
This is how I decouple and mock the ActionController in my controller_spec test file. It is a hodgpodge of my research on what works for Rails 3 and addressing the error messages that arose in my experiments. I don't believe this works because I am either not setting some attribute that ActionController needs or I am inadvertently turning something off. It seems Rails 4 added some complexity to the controller.
APP_ROOT = File.expand_path(File.join(File.dirname__FILE__), "..", "..", ".."))
$: << File.join(APP_ROOT, "app/controllers")
module ActionController
class Base
class << self
attr_reader :before_filters
attr_reader :skipped_before_filters
end
def self.before_filter(*args)
#before_filters ||= []
#before_filters << args
end
def self.skip_before_filter(*args)
#skipped_before_filters ||= []
#skipped_before_filters << args
end
def self.allow_forgery_protection=(val); end
def self.allow_forgery_protection; end
def self.protect_from_forgery(*args); end
def self.after_filter(*args); end
def request=(val); end
def request; end
def params=(val); end
def redirect_to(*args); end
def render_template(*args); end
def _compute_redirect_to_location(*args); end
end
end
These are my spec tests which were passing before I began this experiment:
describe "GET #home" do
subject(:action) {get :home}
it "is successful" do
expect(action).to be_success
end
it "returns HTTP 200 status" do
expect(action.status).to eq(200)
end
it "renders the home template" do
expect(action).to render_template("home")
end
end
My controller action does nothing but render the home view and works as expected:
def home
end
Thank you.
Links about Decoupling in Rails 3:
Running Rails Rspec Tests without Rails
Rails 3, The Great Decoupling