code: def test_window_13173() -> None:
      df = pl.DataFrame(
          data={
              "color": ["yellow", "yellow"],
              "color2": [None, "light"],
              "val": ["2", "3"],
          }
      )
      assert df.with_columns(
          pl.min("val")
          .over(["color", "color2"])
          .alias("min_val_per_color")
      ).to_dict(as_series=False) == {
          "color": ["yellow", "yellow"],
          "color2": [None, "light"],
          "val": ["2", "3"],
          "min_val_per_color": ["2", "3"],
      }
  
imports: from __future__ import annotations
  import numpy
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 20 for calling a global function with example usage: test_window_13173() without return types