code: def _create_dummy_dataset(self):
      dset = Dataset.from_dict(
          {
              "filename": [
                  "my_name-train" + "_" + str(x)
                  for x in np.arange(30).tolist()
              ]
          }
      )
      return dset
  
imports: import os
  import tempfile
  from functools import partial
  from unittest import TestCase
  from unittest.mock import patch
  import numpy
  import pytest
  from datasets.arrow_dataset import Dataset
  from datasets.search import ElasticSearchIndex, FaissIndex, MissingIndex
  from .utils import require_elasticsearch, require_faiss
label_desc: Use image node_id 1 for calling the IndexableDatasetTest obj's underlying member method code with example usage: obj._create_dummy_dataset() and returns: dset