code: def test_transform(self):
      # given
      mock1 = self.DataTransformerMock1()
      mock2 = self.DataTransformerMock2()
      data = constant_timeseries(value=0, length=3)
      transformers = [mock1] * 10 + [mock2] * 10
      p = Pipeline(transformers)
      # when
      p.fit(data)
      transformed = p.transform(data)
  
      # then
      assert 63 == len(transformed)
      assert [0] * 3 + [1] * 30 + [2] * 30 == list(transformed.values())
      for t in transformers:
          assert t.transform_called
          assert not t.inverse_transform_called
  
imports: from typing import Any, Mapping
  import pytest
  from darts import TimeSeries
  from darts.dataprocessing import Pipeline
  from darts.dataprocessing.transformers import BaseDataTransformer, FittableDataTransformer, InvertibleDataTransformer, InvertibleMapper, Mapper
  from darts.utils.timeseries_generation import constant_timeseries
label_desc: Use image node_id 1 for calling the TestPipeline obj's underlying member method code with example usage: obj.test_transform() without return types