Use new "strong parameters" from rails4

spec/controllers/users_controller_spec.rb

@@ -1,28 +1,34 @@
 require 'spec_helper'
 
 describe UsersController do
+  let(:attributes) { FactoryGirl.attributes_for(:user) }
+
   describe 'GET new' do
     it 'assigns a new user as @user' do
       get :new
-      expect(assigns[:user]).to be_a_new(User)
+      expect(assigns[:user]).to be_a_new User
     end
   end
 
   describe 'POST create' do
+    def do_post(params = {})
+      post :create, user: attributes.merge(params)
+    end
+
     context 'whith valid params' do
       it 'creates a new user' do
         expect {
-          post :create, user: FactoryGirl.attributes_for(:user)
+          do_post
         }.to change(User, :count).by(1)
       end
 
       it 'signs the user in' do
-        post :create, user: FactoryGirl.attributes_for(:user)
+        do_post
         expect(controller.current_user).not_to be_nil
       end
 
       it 'redirects to the home page' do
-        post :create, user: FactoryGirl.attributes_for(:user)
+        do_post
         expect(response).to redirect_to :root
       end
     end
@@ -31,12 +37,12 @@ describe UsersController do
       before { allow_any_instance_of(User).to receive(:save) { false } }
 
       it 'assigns the user as @user' do
-        post :create, user: {}
+        do_post
         expect(assigns[:user]).to be_a_new User
       end
 
       it 'renders the new template' do
-        post :create, user: {}
+        do_post
         expect(response).to render_template 'new'
       end
     end