undefined method `assert' error appears while running the code

Hi,

I am new to ruby and I am using ruby with selenium. I want to apply some
validations for login section.
Following is the code on which I am getting error.

@selenium.click "id=loginCloseButton"
    @selenium.click "css=#lnkLogin > span"
    @selenium.click "//button[@id='']"

      begin
        assert @selenium.is_text_present("* Please provide your email
address")
        rescue Test::Unit::AssertionFailedError
        @verification_errors << $!
      end

I am getting following error while running the code:

undefined method `assert' for #<Object:0x298f9e8> (NoMethodError)

Please help me to resolve this issue or tell me any other commands for
that.

Thanks in advance.

Attachments:
http://www.ruby-forum.com/attachment/7056/code.png