Updated Publisher to always create an audit seat for verified course runs

The SeatForm implements the logic to create an audit seat for verified
and credit course runs. It also removes audit seats for professional
course runs.

In the longterm, this should be implemented on the UI and exposed to the
end user to avoid future confusion.

LEARNER-2876

course_discovery/apps/publisher/forms.py

 import html
+import logging
 
+import waffle
 from dal import autocomplete
 from django import forms
 from django.core.exceptions import ValidationError
@@ -18,6 +20,8 @@ from course_discovery.apps.publisher.models import (Course, CourseRun, CourseUse
 from course_discovery.apps.publisher.utils import is_internal_user
 from course_discovery.apps.publisher.validators import validate_text_count
 
+logger = logging.getLogger(__name__)
+
 
 class UserModelChoiceField(forms.ModelChoiceField):
     def label_from_instance(self, obj):
@@ -408,6 +412,21 @@ class SeatForm(BaseForm):
         if commit:
             seat.save()
 
+            if waffle.switch_is_active('publisher_create_audit_seats_for_verified_course_runs'):
+                course_run = seat.course_run
+                audit_seats = course_run.seats.filter(type=Seat.AUDIT)
+
+                # Ensure that course runs with a verified seat always have an audit seat
+                if seat.type in (Seat.CREDIT, Seat.VERIFIED,):
+                    if not audit_seats.exists():
+                        course_run.seats.create(type=Seat.AUDIT, price=0, upgrade_deadline=None)
+                        logger.info('Created audit seat for course run [%d]', course_run.id)
+                elif seat.type != Seat.AUDIT:
+                    # Ensure that professional course runs do NOT have an audit seat
+                    count = audit_seats.count()
+                    audit_seats.delete()
+                    logger.info('Removed [%d] audit seat for course run [%d]', count, course_run.id)
+
         return seat
 
     def clean(self):

course_discovery/apps/publisher/tests/test_forms.py

 from datetime import datetime, timedelta
 
+import pytest
 from django.core.exceptions import ValidationError
 from django.test import TestCase
 from pytz import timezone
+from waffle.testutils import override_switch
 
 from course_discovery.apps.core.models import User
 from course_discovery.apps.core.tests.factories import UserFactory
 from course_discovery.apps.course_metadata.models import Person
 from course_discovery.apps.course_metadata.tests.factories import OrganizationFactory, PersonFactory
-from course_discovery.apps.publisher.forms import CourseForm, CourseRunForm, PublisherUserCreationForm
-from course_discovery.apps.publisher.tests.factories import CourseFactory, OrganizationExtensionFactory
+from course_discovery.apps.publisher.forms import CourseForm, CourseRunForm, PublisherUserCreationForm, SeatForm
+from course_discovery.apps.publisher.models import Seat
+from course_discovery.apps.publisher.tests.factories import CourseFactory, OrganizationExtensionFactory, SeatFactory
 
 
 class UserModelChoiceFieldTests(TestCase):
@@ -190,6 +193,7 @@ class PublisherCustomCourseFormTests(TestCase):
     """
     Tests for publisher 'CourseForm'
     """
+
     def setUp(self):
         super(PublisherCustomCourseFormTests, self).setUp()
         self.course_form = CourseForm()
@@ -265,3 +269,32 @@ class PublisherCustomCourseFormTests(TestCase):
         course_form.save()
         course.refresh_from_db()
         assert course.title == 'áçã'
+
+
+@pytest.mark.django_db
+class TestSeatForm:
+    @override_switch('publisher_create_audit_seats_for_verified_course_runs', active=True)
+    @pytest.mark.parametrize('seat_type', (Seat.NO_ID_PROFESSIONAL, Seat.PROFESSIONAL,))
+    def test_remove_audit_seat_for_professional_course_runs(self, seat_type):
+        seat = SeatFactory(type=seat_type)
+        audit_seat = SeatFactory(type=Seat.AUDIT, course_run=seat.course_run)
+        form = SeatForm(instance=seat)
+        form.save()
+        assert list(seat.course_run.seats.all()) == [seat]
+        assert not Seat.objects.filter(pk=audit_seat.pk).exists()
+
+    @override_switch('publisher_create_audit_seats_for_verified_course_runs', active=True)
+    def test_audit_only_seat_not_modified(self):
+        seat = SeatFactory(type=Seat.AUDIT)
+        form = SeatForm(instance=seat)
+        form.save()
+        assert list(seat.course_run.seats.all()) == [seat]
+
+    @override_switch('publisher_create_audit_seats_for_verified_course_runs', active=True)
+    @pytest.mark.parametrize('seat_type', (Seat.CREDIT, Seat.VERIFIED,))
+    def test_create_audit_seat_for_credit_and_verified_course_runs(self, seat_type):
+        seat = SeatFactory(type=seat_type)
+        form = SeatForm(instance=seat)
+        form.save()
+        assert seat.course_run.seats.count() == 2
+        assert seat.course_run.seats.filter(type=Seat.AUDIT, price=0).exists()

course_discovery/apps/publisher/tests/test_signals.py

@@ -17,7 +17,7 @@ from course_discovery.apps.publisher.tests.factories import CourseRunFactory, Or
 
 @freeze_time('2017-01-01T00:00:00Z')
 @pytest.mark.django_db
-class TestSignals:
+class TestCreateCourseRunInStudio:
     @override_switch('enable_publisher_create_course_run_in_studio', active=True)
     def test_create_course_run_in_studio_without_partner(self):
         with mock.patch('course_discovery.apps.publisher.signals.logger.error') as mock_logger: