code: def test_column_selector(data):
      """
      Checks if column selector works
      :param data: iris dataset from pytest.fixture
      """
      df = pd.DataFrame(data, columns=list("abcd"))
      columns = ["a", "d"]
      selector = ColumnSelector(columns)
      assert selector.column_names == columns
  
      result = selector.fit_transform(df)
      assert result.equals(result[columns])
  
imports: import pandas
  import pytest
  from sklearn.datasets import load_iris
  from greykite.sklearn.transform.column_selector import ColumnSelector
label_desc: Use image node_id 2 for calling a global function with example usage: test_column_selector(data) without return types