code: def test_artifact_manifest_length():
      artifact = Artifact("test-artifact", "test-type")
      assert len(artifact.manifest) == 0
      with artifact.new_file("test.txt") as f:
          f.write("test")
      assert len(artifact.manifest) == 1
  
      testpath = Path("test.txt")
      testpath.write_text("also a test")
      artifact.add_reference(testpath.resolve().as_uri(), "test2.txt")
      assert len(artifact.manifest) == 2
  
imports: import asyncio
  import functools
  import queue
  import shutil
  import unittest.mock
  from pathlib import Path
  from typing import TYPE_CHECKING, Any, Mapping, Optional
  from unittest.mock import Mock
  import pytest
  import requests
  from wandb.filesync.step_prepare import ResponsePrepare, StepPrepare
  from wandb.sdk.artifacts.artifact import Artifact
  from wandb.sdk.artifacts.artifact_file_cache import ArtifactFileCache
  from wandb.sdk.artifacts.artifact_instance_cache import artifact_instance_cache
  from wandb.sdk.artifacts.artifact_manifest_entry import ArtifactManifestEntry
  from wandb.sdk.artifacts.exceptions import ArtifactNotLoggedError
  from wandb.sdk.artifacts.storage_policies.wandb_storage_policy import WandbStoragePolicy
label_desc: Use image node_id 14 for calling a global function with example usage: test_artifact_manifest_length() without return types