class_docstr: Unit test for operator loader.
class_docstr_tok: ["Unit","test","for","operator","loader","."]
code: def test_load_operator_from_path(self):
      op1 = ops.test_revision()
      self.assertEqual(op1()[0], "main")
  
      op1 = ops.test_revision().revision("no-init")
      self.assertEqual(op1()[0], "no-init")
  
      path = operator_cache / "add2"
      op3 = OperatorLoader()._load_operator_from_path(
          path, "towhee/add2", [1], {}
      )  # pylint: disable=protected-access
      self.assertEqual(op3([1, 2, 3]), [2, 3, 4])
  
file_path: towhee/tests/unittests/runtime/test_operator_loader.py
imports: import unittest
  from ..None import operator_cache
  from towhee.runtime import ops
  from towhee.runtime.operator_manager.operator_loader import OperatorLoader
label_desc: Use image node_id 7 for calling the TestOperatorLoader obj's underlying member method code with example usage: obj.test_load_operator_from_path() without return types