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_unknown_engine_raises_error(self) -> None:
      with self.assertRaises(ValueError) as result:
          get_engine("unknown_name")
      msg = str(result.exception)
      assert msg.startswith("Unknown engine name unknown_name")
  
imports: import unittest
  from vissl.engines.engine_registry import Engine, get_engine, register_engine
label_desc: Use image node_id 2 for calling the TestEngineRegistry obj's underlying member method code with example usage: obj.test_unknown_engine_raises_error() without return types