code: def test_columnar_convert_features():
      converter = ColumnarConverter(
          name="some_name",
          default_type="foo",
          type_column=None,
          column_defaults={},
          selected_columns={"x": "x"},
          transform_columns={},
      )
      df = _EMPTY_DF.assign(a=[1, 2], b=[100, 200], x=123)
      ids, columns, type_info = converter.convert(df)
  
      _check_type_info(type_info, [("foo", [[1, 100], [2, 200]])])
      np.testing.assert_array_equal(columns["x"], 123)
  
imports: import networkx
  import numpy
  import pandas
  import pytest
  from stellargraph.core.convert import ColumnarConverter, convert_nodes, convert_edges, from_networkx
  from stellargraph.core.indexed_array import IndexedArray
label_desc: Use image node_id 8 for calling a global function with example usage: test_columnar_convert_features() without return types