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/payments/tests/integration/test_payment_admin.py

@@ -0,0 +1,87 @@
+import json
+
+import pytest
+
+from apps.events.models import Registration
+from apps.payments.models import DiscountCode, Payment
+
+
+pytestmark = [pytest.mark.integration, pytest.mark.django_db]
+
+
+def _send(client, method, path, headers, payload=None):
+    kwargs = dict(headers)
+    if payload is not None:
+        kwargs.update(data=json.dumps(payload), content_type="application/json")
+    return getattr(client, method)(path, **kwargs)
+
+
+def test_discount_code_admin_crud_and_restore(client, user_factory, auth_headers, event_factory):
+    staff = user_factory(is_staff=True)
+    admin = user_factory(is_staff=True, is_superuser=True)
+    member = user_factory()
+    event = event_factory(price=10000)
+    path = "/api/payments/admin/discount-codes"
+    payload = {"code": "pytest10", "type": "percent", "value": 10, "applicable_event_ids": [event.pk]}
+    assert _send(client, "get", path, auth_headers(member)).status_code == 403
+    assert _send(client, "post", path, auth_headers(member), payload).status_code == 403
+    created = _send(client, "post", path, auth_headers(staff), payload)
+    assert created.status_code == 201, created.content
+    code = DiscountCode.objects.get(pk=created.json()["id"])
+    assert code.code == "PYTEST10" and list(code.applicable_events.all()) == [event]
+    assert _send(client, "post", path, auth_headers(staff), payload).status_code == 400
+    assert _send(client, "get", path + "?search=PYTEST10", auth_headers(staff)).json()["count"] == 1
+    changed = _send(client, "put", f"{path}/{code.pk}", auth_headers(staff), {**payload, "value": 20})
+    assert changed.status_code == 200, changed.content
+    code.refresh_from_db()
+    assert code.value == 20
+    assert _send(client, "delete", f"{path}/{code.pk}", auth_headers(staff)).status_code == 403
+    assert _send(client, "delete", f"{path}/{code.pk}", auth_headers(admin)).status_code == 200
+    assert DiscountCode.deleted_objects.filter(pk=code.pk).exists()
+    assert _send(client, "post", f"{path}/{code.pk}/restore", auth_headers(admin)).status_code == 200
+    assert DiscountCode.objects.filter(pk=code.pk).exists()
+
+
+@pytest.mark.parametrize("gateway_result,expected", [({"errors": {"code": -9}}, 502), (None, 502)])
+def test_payment_create_gateway_failures_leave_no_active_payment(client, user_factory, auth_headers, event_factory,
+                                                                 mocker, settings, gateway_result, expected):
+    settings.ZARINPAL_MERCHANT_ID = "test"
+    settings.ZARINPAL_REQUEST_URL = "https://gateway.example/request"
+    user = user_factory()
+    event = event_factory(price=25000)
+    gateway = mocker.patch("apps.payments.api.views.requests.post")
+    if gateway_result is None:
+        gateway.side_effect = RuntimeError("offline")
+    else:
+        gateway.return_value.json.return_value = gateway_result
+    response = _send(client, "post", "/api/payments/create", auth_headers(user),
+                     {"event_id": event.pk, "description": "Ticket"})
+    assert response.status_code == expected
+    assert not Payment.objects.filter(user=user, event=event).exists()
+    assert Registration.objects.filter(user=user, event=event).exists()
+
+
+@pytest.mark.parametrize("gateway_result", [None, {"data": {"code": -1}}])
+def test_payment_callback_verification_failures_notify_once(client, user_factory, event_factory, mocker,
+                                                            settings, gateway_result):
+    settings.ZARINPAL_MERCHANT_ID = "test"
+    settings.ZARINPAL_VERIFY_URL = "https://gateway.example/verify"
+    settings.FRONTEND_CALLBACK_URL = "https://frontend.example/result"
+    user = user_factory()
+    event = event_factory(price=25000)
+    registration = Registration.objects.create(event=event, user=user, status=Registration.StatusChoices.PENDING)
+    payment = Payment.objects.create(user=user, event=event, registration=registration, amount=25000,
+                                     base_amount=25000, authority="AUTH-FAIL", status=Payment.OrderStatusChoices.PENDING)
+    gateway = mocker.patch("apps.payments.api.views.requests.post")
+    notify = mocker.patch("apps.payments.api.views.notify_user")
+    if gateway_result is None:
+        gateway.side_effect = RuntimeError("offline")
+    else:
+        gateway.return_value.json.return_value = gateway_result
+    response = client.get("/api/payments/callback", {"Authority": "AUTH-FAIL", "Status": "OK"})
+    assert response.status_code == 302 and "status=failed" in response.url
+    payment.refresh_from_db()
+    registration.refresh_from_db()
+    assert payment.status == Payment.OrderStatusChoices.FAILED
+    assert registration.status == Registration.StatusChoices.PENDING
+    notify.assert_called_once()