code: def test_progress_bar_with_step_is_none(self):
      train_generator = SomeDataGeneratorUsingStopIteration(
          ModelFittingTestCase.batch_size, 10
      )
      valid_generator = SomeDataGeneratorUsingStopIteration(
          ModelFittingTestCase.batch_size, 10
      )
      _ = self.model.fit_generator(
          train_generator,
          valid_generator,
          epochs=ModelFittingTestCase.epochs,
          progress_options=dict(coloring=False, progress_bar=True),
      )
  
      self.assertStdoutContains(["s/step"])
      self.assertStdoutNotContains(
          ["[32m", "[35m", "[36m", "[94m", "\u2588", "%"]
      )
  
imports: from unittest import skipIf
  import torch
  import torch.nn
  from torch.utils.data import DataLoader
  from poutyne import Model, TensorDataset
  from tests.framework.model.base import ModelFittingTestCase
  from tests.framework.tools import SomeConstantMetric, SomeDataGeneratorUsingStopIteration, repeat_batch_metric, repeat_batch_metric_value, some_batch_metric_1, some_batch_metric_2, some_constant_metric_value, some_data_tensor_generator, some_metric_1_value, some_metric_2_value
label_desc: Use image node_id 17 for calling the ModelFittingTestCaseProgress obj's underlying member method code with example usage: obj.test_progress_bar_with_step_is_none() without return types