new_contents: import unittest, argparse
  from echolalia.formatter.yamler import Formatter
  
  class YamlerTestCase(unittest.TestCase):
  
    def setUp(self):
      self.parser = argparse.ArgumentParser()
      self.data = [{'char': chr(i), 'order': i - 96} for i in xrange(97, 100)]
      self.formatter = Formatter()
  
    def test_add_args(self):
      new_parser = self.formatter.add_args(self.parser)
      self.assertEqual(new_parser, self.parser)
  
    def test_marshall_header(self):
      new_parser = self.formatter.add_args(self.parser)
      args = new_parser.parse_args([])
      result = self.formatter.marshall(args, self.data)
      expect = "- char: a\n  order: 1\n- char: b\n  order: 2\n- char: c\n  order: 3\n"
      self.assertEqual(result, expect)
  
subject: Add tests for formatter yaml