Recursive Patterned File Delete in Ruby/Rake

You don't need to re-implement this wheel. Recursive file glob is already part of the core library.

Dir.glob('C:\Test_Directory\**\*.cs').each { |f| File.delete(f) }

Dir#glob lists files in a directory and can accept wildcards. ** is a super-wildcard that means "match anything, including entire trees of directories", so it will match any level deep (including "no" levels deep: .cs files in C:\Test_Directory itself will also match using the pattern I supplied).

@kkurian points out (in the comments) that File#delete can accept a list, so this could be simplified to:

File.delete(*Dir.glob('C:\Test_Directory\**\*.cs'))

Since you're using Rake already you can use the convenient FileList object. For example:

require 'rubygems'
require 'rake'

FileList['c:/Test_Directory/**/*.cs'].each {|x| File.delete(x)}