Coverage misses Django model tests

I have this model:

class Manager(models.Model):
"""
This model defines a manager. If a User has a Manager record, the User is a manager.
"""

user = models.OneToOneField('users.User', on_delete=models.PROTECT)
static_name = models.CharField(max_length=100)

def __str__(self):
    return 'Manager {}'.format(self.static_name)

class Meta:
    ordering = ('static_name',)
    default_permissions = ['index', 'manage']

def save(self, *args, **kwargs):
    """
    The save method is overwritten to perform a safety check: a patient should never be made a manager.
    """

    if self.user.is_patient or self.user.has_coupled_patient:
        raise ValueError('Een patiënt mag geen manager gemaakt worden.')

    super(Manager, self).save(*args, **kwargs)

With these tests:

class ManagerTest(TestCase):

def setUp(self):
    user1 = User.objects.create(first_name='User', last_name='One', email='user@user.com', password='test')
    user2 = User.objects.create(first_name='User', last_name='with Patient', email='user2@user.com', password='test')
    pharmacy = Pharmacy.objects.create(vidivici_id='2511', name='Pharmacy 1', address='Test', opening_hours='Test')
    couple_request1 = UserPatientCoupleRequest.objects.create(user=user2, couple_last_name='with Patient',
                                                              couple_sex='M', couple_DOB='1980-01-01',
                                                              couple_BSN=123456789, couple_pharmacy=pharmacy)
    patient1 = Patient.objects.create(vidivici_id='25110001', first_name='Patient', last_name='One', sex='M',
                                      DOB='1980-01-01', BSN=123456789, pharmacy=pharmacy)

def test_manager_str(self):
    user = User.objects.get(email='user@user.com')
    manager = Manager.objects.create(user=user, static_name='Manager 1')
    self.assertEqual(str(manager), 'Manager {}'.format(manager.static_name))

def test_manager_save_with_patient(self):
    user_with_patient = User.objects.get(email='user2@user.com')
    patient = Patient.objects.get(vidivici_id='25110001')
    couple_request = UserPatientCoupleRequest.objects.get(user=user_with_patient)
    UserPatient.objects.create(user=user_with_patient, patient=patient, couple_request=couple_request)
    with self.assertRaises(ValueError):
        Manager.objects.create(user=user_with_patient, static_name=user_with_patient.get_full_name())

The tests both pass, but coverage still tells me the __str__ and save methods are not covered. What am I doing wrong? I'm using Django 1.11b1 on Python 3.6. I'm a beginner at testing so it's probably something obvious.