Add owns_thread test

tests/test_permissions.py

@@ -0,0 +1,31 @@
+from django.contrib.auth.models import User
+
+import pytest
+
+from django_ai_assistant.models import Thread
+from django_ai_assistant.permissions import owns_thread
+
+
+@pytest.fixture()
+def superuser(db):
+    return User.objects.create_superuser(username="superuser", password="password")
+
+
+@pytest.fixture()
+def regular_user(db):
+    return User.objects.create_user(username="regular", password="password")
+
+
+@pytest.mark.django_db()
+def test_owns_thread(superuser, regular_user):
+    thread = Thread.objects.create(name="AAA")
+    assert owns_thread(superuser, thread)
+    assert not owns_thread(regular_user, thread)
+
+    thread = Thread.objects.create(name="CCC", created_by=superuser)
+    assert owns_thread(superuser, thread)
+    assert not owns_thread(regular_user, thread)
+
+    thread = Thread.objects.create(name="BBB", created_by=regular_user)
+    assert owns_thread(superuser, thread)
+    assert owns_thread(regular_user, thread)