code: def test_no_data_sparktext():
      """Test no data sparktext"""
      chart2 = Line()
      chart2.add("_", [])
      assert chart2.render_sparktext() == ""
  
      chart3 = Line()
      assert chart3.render_sparktext() == ""
  
file_path: pygal/pygal/test/test_sparktext.py
imports: from pygal import Bar, Line
label_desc: Use image node_id 6 for calling a global function with example usage: test_no_data_sparktext() without return types