code: def test_save_as_text():
      save_as_text(image_data="test data", output_name="test_txt.txt")
      os.unlink("test_txt.txt")
  
file_path: pyecharts/test/test_snapshot.py
imports: import os
  from unittest.mock import patch
  from nose.tools import assert_equal, raises
  from pyecharts.charts import Bar
  from pyecharts.render import make_snapshot
  from pyecharts.render.snapshot import save_as, save_as_png, save_as_text, decode_base64
label_desc: Use image node_id 4 for calling a global function with example usage: test_save_as_text() without return types