new_contents: #!/usr/bin/env python
  """
  :Author Patrik Valkovic
  :Created 31.08.2017 11:55
  :Licence GNUv3
  Part of grammpy
  
  """
  
  
  from unittest import TestCase, main
  from grammpy import *
  from grammpy.exceptions import TreeDeletedException
  
  class A(Nonterminal): pass
  class B(Nonterminal): pass
  class C(Nonterminal): pass
  class From(Rule): rule = ([C], [A, B])
  class To(Rule): rule = ([A], [B, C])
  
  
  class RulesTest(TestCase):
      def test_correctChild(self):
          t = To()
          b = B()
          c = C()
          t._to_nonterms.append(b)
          t._to_nonterms.append(c)
          self.assertEqual(t.to_nonterms[0], b)
          self.assertEqual(t.to_nonterms[1], c)
          self.assertEqual(t.to_nonterms, [b, c])
  
  
  
  
  
  
  if __name__ == '__main__':
      main()
  
subject: Add test for Rule