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_get.py

@@ -0,0 +1,126 @@
+from django.test import TestCase
+
+from .models import Comment, Tenant, User
+
+
+class CompositePKGetTests(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_1,
+            id=2,
+            email="user0002@example.com",
+        )
+        cls.user_3 = User.objects.create(
+            tenant=cls.tenant_2,
+            id=3,
+            email="user0003@example.com",
+        )
+        cls.comment_1 = Comment.objects.create(id=1, user=cls.user_1)
+
+    def test_get_user(self):
+        test_cases = (
+            {"pk": self.user_1.pk},
+            {"pk": (self.tenant_1.id, self.user_1.id)},
+            {"id": self.user_1.id},
+        )
+
+        for lookup in test_cases:
+            with self.subTest(lookup=lookup):
+                self.assertEqual(User.objects.get(**lookup), self.user_1)
+
+    def test_get_comment(self):
+        test_cases = (
+            {"pk": self.comment_1.pk},
+            {"pk": (self.tenant_1.id, self.comment_1.id)},
+            {"id": self.comment_1.id},
+            {"user": self.user_1},
+            {"user_id": self.user_1.id},
+            {"user__id": self.user_1.id},
+            {"user__pk": self.user_1.pk},
+            {"tenant": self.tenant_1},
+            {"tenant_id": self.tenant_1.id},
+            {"tenant__id": self.tenant_1.id},
+            {"tenant__pk": self.tenant_1.pk},
+        )
+
+        for lookup in test_cases:
+            with self.subTest(lookup=lookup):
+                self.assertEqual(Comment.objects.get(**lookup), self.comment_1)
+
+    def test_get_or_create_user(self):
+        test_cases = (
+            {
+                "pk": self.user_1.pk,
+                "defaults": {"email": "user9201@example.com"},
+            },
+            {
+                "pk": (self.tenant_1.id, self.user_1.id),
+                "defaults": {"email": "user9201@example.com"},
+            },
+            {
+                "tenant": self.tenant_1,
+                "id": self.user_1.id,
+                "defaults": {"email": "user3512@example.com"},
+            },
+            {
+                "tenant_id": self.tenant_1.id,
+                "id": self.user_1.id,
+                "defaults": {"email": "user8239@example.com"},
+            },
+        )
+
+        for fields in test_cases:
+            with self.subTest(fields=fields):
+                count = User.objects.count()
+                user, created = User.objects.get_or_create(**fields)
+                self.assertIs(created, False)
+                self.assertEqual(user.id, self.user_1.id)
+                self.assertEqual(user.pk, (self.tenant_1.id, self.user_1.id))
+                self.assertEqual(user.tenant_id, self.tenant_1.id)
+                self.assertEqual(user.email, self.user_1.email)
+                self.assertEqual(count, User.objects.count())
+
+    def test_lookup_errors(self):
+        m_tuple = "'%s' lookup of 'pk' must be a tuple or a list"
+        m_2_elements = "'%s' lookup of 'pk' must have 2 elements"
+        m_tuple_collection = (
+            "'in' lookup of 'pk' must be a collection of tuples or lists"
+        )
+        m_2_elements_each = "'in' lookup of 'pk' must have 2 elements each"
+        test_cases = (
+            ({"pk": 1}, m_tuple % "exact"),
+            ({"pk": (1, 2, 3)}, m_2_elements % "exact"),
+            ({"pk__exact": 1}, m_tuple % "exact"),
+            ({"pk__exact": (1, 2, 3)}, m_2_elements % "exact"),
+            ({"pk__in": 1}, m_tuple % "in"),
+            ({"pk__in": (1, 2, 3)}, m_tuple_collection),
+            ({"pk__in": ((1, 2, 3),)}, m_2_elements_each),
+            ({"pk__gt": 1}, m_tuple % "gt"),
+            ({"pk__gt": (1, 2, 3)}, m_2_elements % "gt"),
+            ({"pk__gte": 1}, m_tuple % "gte"),
+            ({"pk__gte": (1, 2, 3)}, m_2_elements % "gte"),
+            ({"pk__lt": 1}, m_tuple % "lt"),
+            ({"pk__lt": (1, 2, 3)}, m_2_elements % "lt"),
+            ({"pk__lte": 1}, m_tuple % "lte"),
+            ({"pk__lte": (1, 2, 3)}, m_2_elements % "lte"),
+        )
+
+        for kwargs, message in test_cases:
+            with (
+                self.subTest(kwargs=kwargs),
+                self.assertRaisesMessage(ValueError, message),
+            ):
+                Comment.objects.get(**kwargs)
+
+    def test_get_user_by_comments(self):
+        self.assertEqual(User.objects.get(comments=self.comment_1), self.user_1)