docstr: Tests S3 key prefix with sub-directory is properly formated
docstr_tok: ["Tests","S3","key","prefix","with","sub-directory","is","properly","formated"]
code: def test_get_s3_key_prefix_with_subdir(self):
      """
      Tests S3 key prefix with sub-directory is properly formated
      """
      fake_args = TestArtifactRepositoryTool.create_argparse_namespace(
          git_sha="abc123",
          operating_system="linux",
          variant="cpu",
          libtype="static",
      )
  
      self.assertEqual(
          get_s3_key_prefix(fake_args, subdir="subdir"),
          "abc123/static/linux/cpu/subdir/",
      )
  
imports: import unittest
  from unittest.mock import MagicMock, mock_open, patch
  from artifact_repository import *
label_desc: Use image node_id 28 for calling the TestArtifactRepositoryTool obj's underlying member method code with example usage: obj.test_get_s3_key_prefix_with_subdir() without return types