def test_custom_vector_subfield_of_multimodal_should_fail_unstructured(self):
        """
        When attempting to add documents to an unstructured index or a semi-structured index, a custom vector can not
        be a subfield of a multimodal field.
        TODO Remove this test when this functionality becomes available.
        """

        for index in [self.unstructured_custom_index, self.unstructured_custom_index]:
            with self.subTest(f"Index: {index.name}, type: {index.type}"):
                add_docs_res = self.add_documents(
                    config=self.config, add_docs_params=AddDocsParams(
                        index_name=self.unstructured_custom_index.name,
                        docs=[
                            {
                                "_id": "doc0",
                                "my_custom_vector": {
                                    "content": "vec 1",
                                    "vector": self.random_vector_1  # size is 512
                                },
                            }
                        ],
                        device="cpu",
                        tensor_fields=["my_custom_vector", "bad_multimodal"],
                        mappings={
                            "my_custom_vector": {
                                "type": "custom_vector"
                            },
                            "bad_multimodal": {
                                "type": "multimodal_combination",
                                "weights": {
                                    "my_custom_vector": 0.5
                                }
                            }
                        }
                    )
                ).dict(exclude_none=True, by_alias=True)

                self.assertEqual(add_docs_res["errors"], True)
                self.assertEqual(add_docs_res["items"][0]["code"], "invalid_argument")
                self.assertEqual(add_docs_res["items"][0]["status"], 400)
                self.assertIn("Multimodal subfields must be strings", add_docs_res["items"][0]["error"])

        When attempting to add documents to an unstructured index or a semi-structured index, a custom vector can not
        be a subfield of a multimodal field.
        TODO Remove this test when this functionality becomes available.
        
tests/integ_tests/tensor_search/integ_tests/test_custom_vector_field.py