Ruby

=begin
$ ls src/
README
$ ls dst/
$ ruby -e "require 'fileutils; FileUtils::DryRun.copy_entry 'src/', 'dst/'"
$ ls dst/
README
$ ruby -v
ruby 1.9.2p136 (2010-12-25 revision 30365) [i686-linux]

I expected to make no changes and get some messages, but got a change and no messages.

The Reference manual (http://www.ruby-doc.org/stdlib/libdoc/fileutils/rdoc/classes/FileUtils/DryRun.html) said that "never changes files/directories".

I think this mismatch between documents and actual behavior is harmful.

A easiest way to resolve the problem is to remove methods which does not accept 'noop' option from FileUtils::DryRun.
=end