code: def test_generate_fake_fmri_error(rng):
      with pytest.raises(ValueError, match="10 is too small"):
          generate_fake_fmri(
              length=10,
              n_blocks=10,
              block_size=None,
              random_state=rng,
          )
  
imports: from __future__ import annotations
  import json
  import numpy
  import pytest
  from nilearn._utils.data_gen import add_metadata_to_bids_dataset, create_fake_bids_dataset, generate_fake_fmri, generate_labeled_regions, generate_maps, generate_regions_ts
  from nilearn.image import get_data
label_desc: Use image node_id 20 for calling a global function with example usage: test_generate_fake_fmri_error(rng) without return types