culerity_blank_element.rb

def find_button(text)
  button = $browser.element_by_xpath(%\//input[@value="#{text}"]\)
  raise "button #{text} not found" unless button
  button
end

Then /^I should not see button "([^\"]+)"$/ do |text|
  button = find_button(text) rescue nil
  button.should be_nil
end