code: def test_get_sync_none(self, mocker):
      mocker.patch.dict(os.environ, {"KEY1": "value1"})
      provider = EnvSecretProvider()
  
      try:
          secret = provider.get_sync("KEY2")
      except:
          pytest.fail("Unresolved secrets should not throw an error")
  
      assert secret is None
  
file_path: fiftyone/tests/unittests/secrets/provider_tests.py
imports: import os
  import pytest
  from fiftyone.internal.secrets import EnvSecretProvider, UnencryptedSecret, ISecret
label_desc: Use image node_id 2 for calling the TestEnvSecretProvider obj's underlying member method code with example usage: obj.test_get_sync_none(mocker) without return types