code: def test_empty_feature_should_generate_fixed_output(self) -> None:
      feature = EmptyFeature()
      contribution = torch.rand(1).item()
      expected_output = FeatureOutput(
          name="empty",
          base=None,
          modified=None,
          type="empty",
          contribution=contribution,
      )
  
      self.assertEqual(
          expected_output, feature.visualize(None, None, contribution)
      )
  
file_path: captum/tests/insights/test_features.py
imports: from unittest.mock import patch
  import torch
  from captum.insights.attr_vis.features import _convert_figure_base64, EmptyFeature, FeatureOutput, GeneralFeature, ImageFeature, TextFeature
  from matplotlib.figure import Figure
  from tests.helpers.basic import BaseTest
label_desc: Use image node_id 1 for calling the TestEmptyFeature obj's underlying member method code with example usage: obj.test_empty_feature_should_generate_fixed_output() without return types