Watir：如何验证网页中是否没有文本

do_a_faily_thing if not browser.text.include? \"badgers are eating my face\"

do_a_faily_thing unless browser.text.include? \"face-eating-badger-eating-badgers are eating my face-eating badgers\"

if browser.text.include? \"badgers are eating my face\"
   do_a_thing
else
   phew_no_badgers
end

   !browser.text.include?(\"my string\")

# RSpec and/or Cucumber
browser.text.include?(\"my string\").should != true

# TestUnit
assert(browser.text.include?(\"my string\") != true)

<p class=\'foo\'>bar</p>

p(:class,\'foo\').exist?