Getting current user in tests is slow and painful.. but you can do something like this to speed up your test suite. Writing a blog about it sometime in the future.

bypass_auth.rb

  def bypass_current_user(user, &block)
    raise "Block must be given.." unless block_given?
    $current_user = user
    begin
      ApplicationController.class_exec do
        alias original_current_user current_user
        def current_user
          $current_user
        end
        yield
      end
    ensure
      ApplicationController.class_exec do
        if self.instance_methods.include?(:original_current_user)
          $current_user = nil
          alias current_user original_current_user
        end
      end
    end
  end

usage.rb

...

test "do something fancy" do
    bypass_current_user(@user) do
      get_via_redirect '/'
      assert_equal '/', path
    end
end

...