test.exs

  defp sign_in(%User{password_digest: password_digest, id: user_id}, password, conn) do
     if checkpw(password, password_digest) do                                            
       conn                                                                              
       |> put_session(:current_user, user_id)                                            
       |> put_flash(:info, "Sign in successful!")                                        
       |> redirect(to: page_path(conn, :index))                                          
     else                                                                                
       sign_in(nil, nil, conn)                                                           
     end                                                                                 
   end
   
   defp sign_in(_user, _password, conn) do                         
     conn                                                          
     |> put_session(:current_user, nil)                            
     |> put_flash(:error, "Invalid username/password combination!")
     |> redirect(to: page_path(conn, :index))
   end