add initial signup specs

spec/features/users/signin_and_signup_spec.rb

@@ -27,7 +27,11 @@
 
 RSpec.feature 'Sign up', :devise do
   scenario 'a user cannot sign up if already registerd'
-  scenario 'a user can sign up with valid credentials'
+  scenario 'a user can sign up with valid credentials' do
+    user = FactoryGirl.build(:user)
+    signup(user.email, user.password)
+    expect(page).to have_content I18n.t 'devise.registrations.signed_up'
+  end
   scenario 'a user cannot sign up without an email'
   scenario 'a user cannot sign up without a unique email'
   scenario 'a user cannot sign up without a valid password'

spec/support/helpers/session_helpers.rb

@@ -6,5 +6,13 @@ def signin(email, password)
         fill_in 'Password', with: password
         click_button 'Log in'
       end
+
+      def signup(email, password)
+        visit new_user_registration_path
+        fill_in 'Email', with: email
+        fill_in 'Password', with: password
+        fill_in 'Password confirmation', with: password
+        click_button 'Sign up'
+      end
     end
   end