code: def test_group_by_key_name(self):
      table = Table(self.rows, self.column_names, self.column_types)
  
      tableset = table.group_by("one", key_name="test")
  
      self.assertIsInstance(tableset, TableSet)
      self.assertEqual(tableset.key_name, "test")
      self.assertIsInstance(tableset.key_type, Text)
  
      self.assertIn("a", tableset.keys())
      self.assertIn("b", tableset.keys())
      self.assertIn(None, tableset.keys())
  
      self.assertSequenceEqual(tableset["a"].columns["one"], ("a", "a"))
      self.assertSequenceEqual(tableset["b"].columns["one"], ("b",))
  
file_path: agate/tests/test_table/test_group_by.py
imports: from decimal import Decimal
  from agate import Table, TableSet
  from agate.data_types import Boolean, Number, Text
  from agate.testcase import AgateTestCase
label_desc: Use image node_id 4 for calling the TestGroupBy obj's underlying member method code with example usage: obj.test_group_by_key_name() without return types