test: Add test to check duplicated dataset user

argilla-server/tests/unit/database/models/test_dataset_user_model.py

@@ -0,0 +1,40 @@
+#  Copyright 2021-present, the Recognai S.L. team.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+import pytest
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from argilla_server.models import DatasetUser
+from tests.factories import UserFactory, DatasetFactory
+
+
+@pytest.mark.asyncio
+class TestDatasetUserModel:
+    async def test_create_duplicated_dataset_user(self, db: AsyncSession):
+        user = await UserFactory.create()
+        dataset = await DatasetFactory.create()
+
+        db.add_all(
+            [
+                DatasetUser(user_id=user.id, dataset_id=dataset.id),
+                DatasetUser(user_id=user.id, dataset_id=dataset.id),
+            ]
+        )
+
+        with pytest.raises(
+            IntegrityError,
+            match="UNIQUE constraint failed: datasets_users.dataset_id, datasets_users.user_id",
+        ):
+            await db.commit()