code: def test_convert_date_val_to_date():
      assert (
          chart_utils.convert_date_val_to_date("2020-01-01").strftime(
              "%Y%m%d"
          )
          == "20200101"
      )
      assert (
          chart_utils.convert_date_val_to_date(1577854800000).strftime(
              "%Y%m%d"
          )
          == "20200101"
      )
  
file_path: dtale/tests/dtale/charts/test_utils.py
imports: import mock
  import pytest
  import dtale.charts.utils
  from tests import ExitStack
  from tests.dtale.test_charts import build_col_def
label_desc: Use image node_id 5 for calling a global function with example usage: test_convert_date_val_to_date() without return types