more flexible login in spec helper

spec/integration/session_spec.rb

@@ -9,7 +9,7 @@ describe 'the session', :type => :feature do
       expect(response).to be_success
     end
     it 'logs me in' do
-      login user.nick, user.password
+      login user
       expect(page).to_not have_selector('.alert-error')
     end
     it 'does not log me in with wrong password' do

spec/support/session_helper.rb

@@ -1,12 +1,10 @@
 
 module SessionHelper
 
-  def login(nick=nil, password=nil)
+  def login(user=nil, password=nil)
     visit login_path
-    if nick.nil?
-      user = FactoryGirl.create :user
-      nick, password = user.nick, user.password
-    end
+    user = FactoryGirl.create :user if user.nil?
+    nick, password = user.nick, user.password if user.instance_of? ::User
     fill_in 'nick', :with => nick
     fill_in 'password', :with => password
     find('input[type=submit]').click