/vendor/gems/facets-2.4.5/test/core/file/test_rewrite.rb

require 'facets/file/rewrite'
require 'test/unit'
#require 'tempfile'

class Tets_File_Rewrite < Test::Unit::TestCase

   class MockFile < ::File
     def self.open( fname, mode, &blk )
       blk.call(self)
     end
     def self.read( fname=nil )
       @mock_content.clone
     end
     def self.write( str )
       @mock_content = str
     end
     def self.<<( str )
       (@mock_content ||="") << str
     end
   end

   def test_rewrite
     f = "not-a-real-file.txt"
     t = 'This is a test!'
     MockFile.write( t )
     MockFile.rewrite(f) { |s| s.reverse }
     s = MockFile.read(f)
     assert_equal( t.reverse, s )
   end

end