code: def test_json(handle_fn, base_model_context):
      test_data = [{"body": {"instances": [[1.0, 2.0]]}}]
      expected_result = ['{"predictions": [1]}']
  
      envelope = JSONEnvelope(handle_fn)
      results = envelope.handle(test_data, base_model_context)
      assert results == expected_result
  
file_path: serve/ts/torch_handler/unit_tests/test_envelopes.py
imports: import pytest
  from ts.torch_handler.base_handler import BaseHandler
  from ts.torch_handler.request_envelope.body import BodyEnvelope
  from ts.torch_handler.request_envelope.json import JSONEnvelope
label_desc: Use image node_id 2 for calling a global function with example usage: test_json(handle_fn, base_model_context) without return types