Add comprehensive tests for Parks API and models

- Implemented extensive test cases for the Parks API, covering endpoints for listing, retrieving, creating, updating, and deleting parks.
- Added tests for filtering, searching, and ordering parks in the API.
- Created tests for error handling in the API, including malformed JSON and unsupported methods.
- Developed model tests for Park, ParkArea, Company, and ParkReview models, ensuring validation and constraints are enforced.
- Introduced utility mixins for API and model testing to streamline assertions and enhance test readability.
- Included integration tests to validate complete workflows involving park creation, retrieval, updating, and deletion.

parks/models/reviews.py

@@ -1,10 +1,16 @@
 from django.db import models
+from django.db.models import functions
 from django.core.validators import MinValueValidator, MaxValueValidator
 from core.history import TrackedModel
 import pghistory
 
 @pghistory.track()
 class ParkReview(TrackedModel):
+    
+    # Import managers  
+    from ..managers import ParkReviewManager
+    
+    objects = ParkReviewManager()
     """
     A review of a park.
     """
@@ -44,6 +50,27 @@ class ParkReview(TrackedModel):
     class Meta:
         ordering = ['-created_at']
         unique_together = ['park', 'user']
+        constraints = [
+            # Business rule: Rating must be between 1 and 10 (database level enforcement)
+            models.CheckConstraint(
+                name="park_review_rating_range",
+                check=models.Q(rating__gte=1) & models.Q(rating__lte=10),
+                violation_error_message="Rating must be between 1 and 10"
+            ),
+            # Business rule: Visit date cannot be in the future
+            models.CheckConstraint(
+                name="park_review_visit_date_not_future",
+                check=models.Q(visit_date__lte=functions.Now()),
+                violation_error_message="Visit date cannot be in the future"
+            ),
+            # Business rule: If moderated, must have moderator and timestamp
+            models.CheckConstraint(
+                name="park_review_moderation_consistency",
+                check=models.Q(moderated_by__isnull=True, moderated_at__isnull=True) | 
+                      models.Q(moderated_by__isnull=False, moderated_at__isnull=False),
+                violation_error_message="Moderated reviews must have both moderator and moderation timestamp"
+            ),
+        ]
 
     def __str__(self):
         return f"Review of {self.park.name} by {self.user.username}"