docstr: Tests FileNotFound error thrown if file not found
docstr_tok: ["Tests","FileNotFound","error","thrown","if","file","not","found"]
code: def test_is_file_not_found(self, mock_exists):
      """
      Tests FileNotFound error thrown if file not found
      """
      mock_exists.return_value = False
      with self.assertRaises(FileNotFoundError) as ctx:
          is_file("some/path")
      self.assertEqual(
          str(ctx.exception), "File '{}' not found".format("some/path")
      )
  
imports: import unittest
  from unittest.mock import MagicMock, mock_open, patch
  from artifact_repository import *
label_desc: Use image node_id 36 for calling the TestArtifactRepositoryTool obj's underlying member method code with example usage: obj.test_is_file_not_found(mock_exists) without return types