code: def test_reorder_columns():
      """Tests reorder_columns"""
      df = pd.DataFrame(np.random.randn(3, 4), columns=list("abcd"))
      reordered_df = reorder_columns(df, order_dict=None)
      assert_equal(df, reordered_df)
  
      order_dict = {"a": 3, "b": -1, "c": 5, "d": 2}
      reordered_df = reorder_columns(df, order_dict=order_dict)
      assert_equal(df[["b", "d", "a", "c"]], reordered_df)
  
imports: import warnings
  from dataclasses import dataclass
  from typing import List
  import numpy
  import pandas
  import pytest
  import scipy
  from greykite.common import constants
  from greykite.common.evaluation import ElementwiseEvaluationMetricEnum
  from greykite.common.python_utils import apply_func_to_columns
  from greykite.common.python_utils import assert_equal
  from greykite.common.python_utils import dictionaries_values_to_lists
  from greykite.common.python_utils import dictionary_values_to_lists
  from greykite.common.python_utils import flatten_list
  from greykite.common.python_utils import get_integer
  from greykite.common.python_utils import get_pattern_cols
  from greykite.common.python_utils import group_strs_with_regex_patterns
  from greykite.common.python_utils import ignore_warnings
  from greykite.common.python_utils import mutable_field
  from greykite.common.python_utils import reorder_columns
  from greykite.common.python_utils import split_offset_str
  from greykite.common.python_utils import unique_dict_in_list
  from greykite.common.python_utils import unique_elements_in_list
  from greykite.common.python_utils import unique_in_list
  from greykite.common.python_utils import update_dictionaries
  from greykite.common.python_utils import update_dictionary
label_desc: Use image node_id 12 for calling a global function with example usage: test_reorder_columns() without return types