old_contents: from unittest import TestCase
  
  from basics import BaseCharacter
  from basics import BaseAttachment
  
  
  class ModuleTest(TestCase):
  
      def test_character_attach_attachment(self):
          character = BaseCharacter().save()
          attachment = BaseAttachment().save()
  
          # Attachment should not be among the character's attachments
          self.assertNotIn(attachment.id, character.attachments())
  
          # Attach the attachment
          character.attach(attachment)
  
          # Attachment should be among the character's attachments
          self.assertIn(attachment.id, character.attachments())
  
      def test_container_containment(self):
          self.fail("Test unwritten")
  
new_contents: from unittest import TestCase
  
  from basics import BaseCharacter
  from basics import BaseAttachment
  from basics import BaseThing
  
  
  class ModuleTest(TestCase):
  
      def test_character_attach_attachment(self):
          character = BaseCharacter().save()
          attachment = BaseAttachment().save()
  
          # Attachment should not be among the character's attachments
          self.assertNotIn(attachment.id, character.attachments())
  
          # Attach the attachment
          character.attach(attachment)
  
          # Attachment should be among the character's attachments
          self.assertIn(attachment.id, character.attachments())
  
      def test_container_containment(self):
          thing_a = BaseThing().save()
          thing_b = BaseThing().save()
  
          # thing_b should not be among thing_a's stuff
          self.assertNotIn(thing_b.id, thing_a.stuff())
  
          # thing_b aint contained
          self.assertIsNone(thing_b.container())
  
          # Move thing_b into thing_a
          thing_b.move_to(thing_a)
  
          # thing_b should be among thing_a's stuff
          self.assertIn(thing_b.id, thing_a.stuff())
  
          # thing_b is contained by thing_a
          self.assertEqual(thing_a, thing_b.container())
  
  
subject: Write test for container containment.