def f_login(session_stubs = {}, user_stubs = {})
  UserSession.stub(:find).and_return(f_user_session(session_stubs, user_stubs))
end

def f_user_session(stubs = {}, user_stubs = {})
  @current_user_session ||= mock(UserSession, {:user => f_current_user(user_stubs).merge(stubs)})
end

def f_current_user(stubs = {})
  @current_user ||= mock(User, stubs)
end

def f_logout
  @current_user_session = nil
end