docstr: Check the component is executed exactly once.
docstr_tok: ["Check","the","component","is","executed","exactly","once","."]
code: def assertExecutedOnce(self, component: str) -> None:
      """Check the component is executed exactly once."""
      component_path = os.path.join(self._pipeline_root, component)
      self.assertTrue(fileio.exists(component_path))
      execution_path = os.path.join(
          component_path, ".system", "executor_execution"
      )
      execution = fileio.listdir(execution_path)
      self.assertLen(execution, 1)
  
imports: import importlib
  import os
  from typing import List
  from absl import logging
  from absl.testing import parameterized
  import tensorflow
  from tfx.examples.penguin import penguin_pipeline_local
  from tfx.v1 import proto
  from tfx.v1.dsl.io import fileio
  from tfx.v1.orchestration import LocalDagRunner
  from tfx.v1.orchestration import metadata
  import ml_metadata
  from ml_metadata.proto import metadata_store_pb2
label_desc: Use image node_id 3 for calling the PenguinPipelineLocalEndToEndTest obj's underlying member method code with example usage: obj.assertExecutedOnce(component) without return types