public void When_using_strongly_typed_OnSendingHeaders_it_should_be_invoked_at_sending_headers()
        {
            var owinResponse = new OwinResponse();

            owinResponse.Environment["server.OnSendingHeaders"] = new Action <Action <object>, object>((action, obj) => action(obj));
            owinResponse.OnSendingHeaders(str =>
            {
                str.ShouldBeTypeOf(typeof(string));
                str.ShouldBe("Strongly typed!");
            }, "Strongly typed!");
        }