new_contents: from symposion.conference.models import Section
  from symposion.proposals.models import ProposalBase
  from symposion.schedule.models import Presentation
  
  from conf_site.proposals.tests import ProposalTestCase
  
  
  class PresentationProposalConnectionTestCase(ProposalTestCase):
      def test_presentation_proposal_model(self):
          """Make sure presentation.proposal is Proposal, not ProposalBase."""
          # Create Presentation connected to existing Proposal.
          proposal_base = ProposalBase.objects.get(
              title=self.proposal.title,
              description=self.proposal.description,
              abstract=self.proposal.abstract,
              speaker=self.proposal.speaker,
          )
          presentation = Presentation.objects.create(
              title=self.proposal.title,
              description=self.proposal.description,
              abstract=self.proposal.abstract,
              speaker=self.proposal.speaker,
              section=Section.objects.first(),
              proposal_base=proposal_base,
          )
          # This should be a Proposal, not a ProposalBase.
          self.assertIs(type(presentation.proposal), type(self.proposal))
  
subject: Add test case for Presentation-Proposal connection.