feat: added pagination and deletion guard

api/experimentation/views.py

@@ -1,14 +1,16 @@
 import logging
 from typing import Any
 
+from django.db import IntegrityError
 from django.db.models import Q, QuerySet
-from rest_framework import mixins, status
+from rest_framework import mixins, serializers, status
 from rest_framework.decorators import action
 from rest_framework.permissions import IsAuthenticated
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.serializers import BaseSerializer
 
+from app.pagination import CustomPagination
 from environments.views import NestedEnvironmentViewSet
 from experimentation.models import (
     Experiment,
@@ -101,7 +103,7 @@ class ExperimentViewSet(
     mixins.DestroyModelMixin,
 ):
     serializer_class = ExperimentSerializer
-    pagination_class = None
+    pagination_class = CustomPagination
     permission_classes = [IsAuthenticated, ExperimentPermission]
     model_class = Experiment
     lookup_field = "id"
@@ -125,6 +127,10 @@ def get_queryset(self) -> "QuerySet[Experiment]":
             )
         status_filter = self.request.query_params.get("status")
         if status_filter:
+            if status_filter not in ExperimentStatus.values:
+                raise serializers.ValidationError(
+                    {"status": f"Invalid status '{status_filter}'."}
+                )
             qs = qs.filter(status=status_filter)
 
         q = self.request.query_params.get("q")
@@ -152,7 +158,13 @@ def create(self, request: Request, *args: object, **kwargs: object) -> Response:
                 status=status.HTTP_409_CONFLICT,
             )
 
-        self.perform_create(serializer)
+        try:
+            self.perform_create(serializer)
+        except IntegrityError:
+            return Response(
+                {"detail": "An active experiment already exists for this feature."},
+                status=status.HTTP_409_CONFLICT,
+            )
         return Response(serializer.data, status=status.HTTP_201_CREATED)
 
     def perform_create(self, serializer: BaseSerializer[Experiment]) -> None:
@@ -162,12 +174,28 @@ def perform_create(self, serializer: BaseSerializer[Experiment]) -> None:
         )
 
     def perform_update(self, serializer: BaseSerializer[Experiment]) -> None:
+        changed_fields = {
+            field
+            for field, value in serializer.validated_data.items()
+            if getattr(serializer.instance, field, None) != value
+        }
+        if not changed_fields:
+            return
         experiment: Experiment = serializer.save()
         create_experiment_audit_log(
             experiment, self._get_user(self.request), action="updated"
         )
 
     def perform_destroy(self, instance: Experiment) -> None:
+        if instance.status == ExperimentStatus.RUNNING:
+            raise serializers.ValidationError(
+                {
+                    "detail": (
+                        "Cannot delete a running experiment. "
+                        "Pause or complete it first."
+                    )
+                }
+            )
         create_experiment_audit_log(
             instance, self._get_user(self.request), action="deleted"
         )

api/tests/unit/experimentation/test_experiment_views.py

@@ -3,7 +3,9 @@
 from typing import TYPE_CHECKING
 
 import pytest
+from django.db import IntegrityError
 from django.urls import reverse
+from pytest_mock import MockerFixture
 from rest_framework import status
 from rest_framework.test import APIClient
 
@@ -265,8 +267,9 @@ def test_get_list__with_experiments__returns_all(
 
     # Then
     assert response.status_code == status.HTTP_200_OK
-    assert len(response.json()) == 1
-    assert response.json()[0]["id"] == experiment.id
+    results = response.json()["results"]
+    assert len(results) == 1
+    assert results[0]["id"] == experiment.id
 
 
 def test_get_list__with_experiments__returns_nested_feature(
@@ -284,9 +287,9 @@ def test_get_list__with_experiments__returns_nested_feature(
 
     # Then
     assert response.status_code == status.HTTP_200_OK
-    data = response.json()
-    assert len(data) == 1
-    feature_data = data[0]["feature"]
+    results = response.json()["results"]
+    assert len(results) == 1
+    feature_data = results[0]["feature"]
     assert isinstance(feature_data, dict)
     assert feature_data["id"] == multivariate_feature.id
     assert feature_data["name"] == multivariate_feature.name
@@ -329,7 +332,7 @@ def test_get_list__empty__returns_200(
 
     # Then
     assert response.status_code == status.HTTP_200_OK
-    assert response.json() == []
+    assert response.json()["results"] == []
 
 
 @pytest.mark.parametrize(
@@ -357,7 +360,7 @@ def test_get_list__filter_by_status__returns_filtered(
 
     # Then
     assert response.status_code == status.HTTP_200_OK
-    assert len(response.json()) == expected_count
+    assert len(response.json()["results"]) == expected_count
 
 
 def test_get_list__search_by_experiment_name__returns_matching(
@@ -374,8 +377,9 @@ def test_get_list__search_by_experiment_name__returns_matching(
 
     # Then
     assert response.status_code == status.HTTP_200_OK
-    assert len(response.json()) == 1
-    assert response.json()[0]["id"] == experiment.id
+    results = response.json()["results"]
+    assert len(results) == 1
+    assert results[0]["id"] == experiment.id
 
 
 def test_get_list__search_by_feature_name__returns_matching(
@@ -395,8 +399,9 @@ def test_get_list__search_by_feature_name__returns_matching(
 
     # Then
     assert response.status_code == status.HTTP_200_OK
-    assert len(response.json()) == 1
-    assert response.json()[0]["id"] == experiment.id
+    results = response.json()["results"]
+    assert len(results) == 1
+    assert results[0]["id"] == experiment.id
 
 
 def test_get_list__search_no_match__returns_empty(
@@ -413,7 +418,7 @@ def test_get_list__search_no_match__returns_empty(
 
     # Then
     assert response.status_code == status.HTTP_200_OK
-    assert len(response.json()) == 0
+    assert len(response.json()["results"]) == 0
 
 
 def test_get_detail__exists__returns_200(
@@ -670,3 +675,93 @@ def test_delete__valid_delete__creates_audit_log(
     ).last()
     assert audit is not None
     assert "deleted" in audit.log
+
+
+def test_get_list__invalid_status__returns_400(
+    admin_client_new: APIClient,
+    environment: Environment,
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given
+    enable_features(EXPERIMENT_FLAG)
+
+    # When
+    response = admin_client_new.get(_list_url(environment), {"status": "garbage"})
+
+    # Then
+    assert response.status_code == status.HTTP_400_BAD_REQUEST
+
+
+def test_delete__running_experiment__returns_400(
+    admin_client_new: APIClient,
+    environment: Environment,
+    experiment: Experiment,
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given
+    enable_features(EXPERIMENT_FLAG)
+    experiment.status = ExperimentStatus.RUNNING
+    experiment.save()
+
+    # When
+    response = admin_client_new.delete(_detail_url(environment, experiment))
+
+    # Then
+    assert response.status_code == status.HTTP_400_BAD_REQUEST
+    assert Experiment.objects.filter(id=experiment.id).exists()
+
+
+def test_patch__no_change__skips_audit_log(
+    admin_client_new: APIClient,
+    environment: Environment,
+    experiment: Experiment,
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given
+    enable_features(EXPERIMENT_FLAG)
+    audit_count_before = AuditLog.objects.filter(
+        related_object_type=RelatedObjectType.EXPERIMENT.name
+    ).count()
+
+    # When
+    response = admin_client_new.patch(
+        _detail_url(environment, experiment),
+        data={"name": experiment.name},
+        format="json",
+    )
+
+    # Then
+    assert response.status_code == status.HTTP_200_OK
+    audit_count_after = AuditLog.objects.filter(
+        related_object_type=RelatedObjectType.EXPERIMENT.name
+    ).count()
+    assert audit_count_after == audit_count_before
+
+
+def test_post__concurrent_create_race__returns_409(
+    admin_client_new: APIClient,
+    environment: Environment,
+    multivariate_feature: Feature,
+    enable_features: EnableFeaturesFixture,
+    mocker: MockerFixture,
+) -> None:
+    # Given
+    enable_features(EXPERIMENT_FLAG)
+    mocker.patch(
+        "experimentation.views.ExperimentViewSet.perform_create",
+        side_effect=IntegrityError(),
+    )
+
+    # When
+    response = admin_client_new.post(
+        _list_url(environment),
+        data={
+            "feature": multivariate_feature.id,
+            "name": "Race",
+            "hypothesis": "Should 409",
+        },
+        format="json",
+    )
+
+    # Then
+    assert response.status_code == status.HTTP_409_CONFLICT