Fixed #373 -- Added CompositePrimaryKey.

Thanks Lily Foote and Simon Charette for reviews and mentoring
this Google Summer of Code 2024 project.

Co-authored-by: Simon Charette <charette.s@gmail.com>
Co-authored-by: Lily Foote <code@lilyf.org>

tests/composite_pk/test_delete.py

@@ -0,0 +1,83 @@
+from django.test import TestCase
+
+from .models import Comment, Tenant, User
+
+
+class CompositePKDeleteTests(TestCase):
+    maxDiff = None
+
+    @classmethod
+    def setUpTestData(cls):
+        cls.tenant_1 = Tenant.objects.create()
+        cls.tenant_2 = Tenant.objects.create()
+        cls.user_1 = User.objects.create(
+            tenant=cls.tenant_1,
+            id=1,
+            email="user0001@example.com",
+        )
+        cls.user_2 = User.objects.create(
+            tenant=cls.tenant_2,
+            id=2,
+            email="user0002@example.com",
+        )
+        cls.comment_1 = Comment.objects.create(id=1, user=cls.user_1)
+        cls.comment_2 = Comment.objects.create(id=2, user=cls.user_2)
+        cls.comment_3 = Comment.objects.create(id=3, user=cls.user_2)
+
+    def test_delete_tenant_by_pk(self):
+        result = Tenant.objects.filter(pk=self.tenant_1.pk).delete()
+
+        self.assertEqual(
+            result,
+            (
+                3,
+                {
+                    "composite_pk.Comment": 1,
+                    "composite_pk.User": 1,
+                    "composite_pk.Tenant": 1,
+                },
+            ),
+        )
+
+        self.assertIs(Tenant.objects.filter(pk=self.tenant_1.pk).exists(), False)
+        self.assertIs(Tenant.objects.filter(pk=self.tenant_2.pk).exists(), True)
+        self.assertIs(User.objects.filter(pk=self.user_1.pk).exists(), False)
+        self.assertIs(User.objects.filter(pk=self.user_2.pk).exists(), True)
+        self.assertIs(Comment.objects.filter(pk=self.comment_1.pk).exists(), False)
+        self.assertIs(Comment.objects.filter(pk=self.comment_2.pk).exists(), True)
+        self.assertIs(Comment.objects.filter(pk=self.comment_3.pk).exists(), True)
+
+    def test_delete_user_by_pk(self):
+        result = User.objects.filter(pk=self.user_1.pk).delete()
+
+        self.assertEqual(
+            result, (2, {"composite_pk.User": 1, "composite_pk.Comment": 1})
+        )
+
+        self.assertIs(User.objects.filter(pk=self.user_1.pk).exists(), False)
+        self.assertIs(User.objects.filter(pk=self.user_2.pk).exists(), True)
+        self.assertIs(Comment.objects.filter(pk=self.comment_1.pk).exists(), False)
+        self.assertIs(Comment.objects.filter(pk=self.comment_2.pk).exists(), True)
+        self.assertIs(Comment.objects.filter(pk=self.comment_3.pk).exists(), True)
+
+    def test_delete_comments_by_user(self):
+        result = Comment.objects.filter(user=self.user_2).delete()
+
+        self.assertEqual(result, (2, {"composite_pk.Comment": 2}))
+
+        self.assertIs(Comment.objects.filter(pk=self.comment_1.pk).exists(), True)
+        self.assertIs(Comment.objects.filter(pk=self.comment_2.pk).exists(), False)
+        self.assertIs(Comment.objects.filter(pk=self.comment_3.pk).exists(), False)
+
+    def test_delete_without_pk(self):
+        msg = (
+            "Comment object can't be deleted because its pk attribute is set "
+            "to None."
+        )
+
+        with self.assertRaisesMessage(ValueError, msg):
+            Comment().delete()
+        with self.assertRaisesMessage(ValueError, msg):
+            Comment(tenant_id=1).delete()
+        with self.assertRaisesMessage(ValueError, msg):
+            Comment(id=1).delete()