class_docstr: For testing of AttrTree
class_docstr_tok: ["For","testing","of","AttrTree"]
code: def test_lowercase_attribute_error(self):
      msg = r"'AttrTree' object has no attribute c\."
      with pytest.raises(AttributeError, match=msg):
          self.tree.c
  
imports: import pytest
  from holoviews.core.element import AttrTree
  from holoviews.element.comparison import ComparisonTestCase
label_desc: Use image node_id 6 for calling the AttrTreeTest obj's underlying member method code with example usage: obj.test_lowercase_attribute_error() without return types