def METHOD_NAME(self):
    url = reverse(
        "person-create",
        kwargs={
            "ballot_paper_id": self.dulwich_post_ballot.ballot_paper_id
        },
    )
    response = self.app.get(url, user=self.user)
    form = response.forms["new-candidate-form"]
    # get the display value from the party choices loaded by the form
    party_choices = [
        party[-1] for party in form["party_identifier_0"].options
    ]
    # get all party names from the db
    party_names = Party.objects.values_list("name", flat=True)
    # check parties are in the choices
    for name in party_names:
        with self.subTest(msg=name):
            self.assertIn(name, party_choices)