cucumber_warning_catcher_steps.rb

# Even with the added strengths of Ruby 1.9.2, it turns out to be tricky to write a Cucumber
# story that specifies something like
# 
#    "Then no warning message should be produced"
#
# As a holdover until I find something safer, I've had to redirect Ruby's $stderr stream
# to a StringIO instance, examine that in the step definition, and reset it to the STDERR
# default after the fact.

require 'stringio'

Before do
  @mistakes = StringIO.open('','r+')
  $stderr = @mistakes
end

After do
  $stderr = STDERR
end

...

Then /^no warning message should be produced$/ do
  @mistakes.rewind
  @mistakes.read.should == ""
end