test: migrate backend suites to pytest with module coverage gate

Split backend tests into unit and integration suites, add isolated fixtures and coverage enforcement, and update CI and test documentation. Cover current authentication, content, notification, payment, media, and admin flows; fix behaviors revealed by the new tests. Validate both suites and the per-module gate against local PostgreSQL.

apps/communications/tests/integration/test_announcements.py

@@ -0,0 +1,29 @@
+import pytest
+import json
+from apps.communications.models import Announcement
+from apps.users.models import User
+from core.authentication import create_jwt_token
+
+@pytest.mark.django_db
+@pytest.mark.integration
+class TestAnnouncementDeliveryTests:
+
+    def setup_method(self):
+        self.staff = User.objects.create_user(username='announcement_staff', mobile='09193000001', password='password', is_staff=True)
+        self.auth = {'HTTP_AUTHORIZATION': f'Bearer {create_jwt_token(self.staff)}'}
+
+    def test_publishing_announcement_does_not_send_manual_notifications(self, mocker):
+        notify_user = mocker.patch('apps.notifications.services.notify_user')
+        response = self.client.post('/api/communications/announcements/', json.dumps({'title': 'News', 'content': '# Story', 'is_published': True}), content_type='application/json', **self.auth)
+        assert response.status_code == 200
+        assert Announcement.objects.filter(title='News').exists()
+        notify_user.assert_not_called()
+
+    def test_newsletter_category_and_routes_are_removed(self):
+        response = self.client.post('/api/communications/announcements/', json.dumps({'title': 'News', 'content': 'Story', 'announcement_type': 'newsletter'}), content_type='application/json', **self.auth)
+        assert response.status_code == 422
+        assert self.client.post('/api/communications/newsletter/subscribe/').status_code == 404
+
+    @pytest.fixture(autouse=True)
+    def _pytest_client(self, client):
+        self.client = client