require 'test/unit'
require 'ftools'
class Test::Unit::TestCase
  #
  #Takes the content of the file 'filename' and compares it with 'actual' like in assert_equal.
  #If 'filname' doesn't exist, the failure 
  # Reference file <#{filename}> missing
  #is returned.
  #
  #'folder_for_failure' will contain all results with differences.
  #
  #Recommendation to build up your test.
  #1) Create two folders: 'expected' and 'failure'
  #2) Define your assertion with a non-existing filename
  #3) Run the test with folder_for_failure = 'failure'
  #4) You will get a failure (filename is missing).
  #5) Copy the file in 'failure' to 'expected'
  #6) Rerun again, you hav no failure (hopefully ;-) )
  def assert_equal_filecontent( filename, actual, folder_for_failure = nil, message = nil )
    if File.exist?(filename)
      expected = File.readlines(filename).to_s 
      full_message = build_message(message, "<?> expected (#{filename}) but was\n<?>.\n", expected, actual)
    else
      full_message = "Reference file <#{filename}> missing"
    end
    #Write the real result to a file.
    #Folder is defined with Test::Unit::TestCase#folder_for_failure
    if folder_for_failure and expected  != actual
      File.makedirs(folder_for_failure) if ! File.directory?(folder_for_failure)
      File.open( "#{folder_for_failure}/#{File.basename(filename)}", 'w'){|f|
        f << actual
      }
    end
    assert_block( full_message ){ expected  == actual }
  end
  #
end

class MyTest < Test::Unit::TestCase 
  def test_myblock()
    folder_for_failure  = 'failure'
    assert_equal_filecontent( 'expected/test.yaml', ['aaa'].to_yaml, folder_for_failure )
    assert_equal_filecontent( 'expected/test2.yaml', {1=> 'eins', 2 => 'zwei'}.to_yaml, folder_for_failure)
  end
end

  full_message = if File.exist?(filename)
                             expected = File.readlines(filename).to_s
                            build_message(message, "<?> expected (#{filename}) but was\n<?>.\n", expected, actual)
                  else
                      "Reference file <#{filename}> missing"
                  end