class_docstr: Test that the engine registry allows to:
  - select the right engine based on the configuration
  - deal with the typical error cases (unknowns, duplicates, etc)
code: def test_duplicate_engine_registration_error(self) -> None:
      with self.assertRaises(ValueError) as result:
  
          @register_engine("train")
          class Duplicate(Engine):
              def run_engine(self, *args, **kwargs):
                  pass
  
      msg = str(result.exception)
      assert msg.startswith("Engine (train) already registered at")
  
imports: import unittest
  from vissl.engines.engine_registry import Engine, get_engine, register_engine
label_desc: Use image node_id 3 for calling the TestEngineRegistry obj's underlying member method code with example usage: obj.test_duplicate_engine_registration_error() without return types