new_contents: import sqlalchemy as sa
  from six import PY3
  
  from tests import TestCase
  
  
  class TestCommonBaseClass(TestCase):
      def create_models(self):
          class TextItem(self.Model):
              __tablename__ = 'text_item'
              __versioned__ = {}
  
              id = sa.Column(sa.Integer, autoincrement=True, primary_key=True)
  
              name = sa.Column('_name', sa.String)
  
          self.TextItem = TextItem
  
      def test_insert(self):
          item = self.TextItem(name=u'Something')
          self.session.add(item)
          self.session.commit()
          assert item.versions[0].name == u'Something'
  
      def test_revert(self):
          item = self.TextItem(name=u'Something')
          self.session.add(item)
          self.session.commit()
          item.name = u'Some other thing'
          self.session.commit()
          item.versions[0].revert()
          self.session.commit()
  
subject: Add failing test case for #40