docstr: Test case where 'ds' exists as an index name and column. Prophet should use the column.
docstr_tok: ["Test","case","where","'ds","'","exists","as","an","index","name","and","column",".","Prophet","should","use","the","column","."]
code: def test_setup_dataframe_ds_column(
      self, daily_univariate_ts, backend
  ):
      """Test case where 'ds' exists as an index name and column. Prophet should use the column."""
      train, _ = train_test_split(
          daily_univariate_ts, daily_univariate_ts.shape[0] // 2
      )
      train.index = pd.to_datetime(
          ["1970-01-01" for _ in range(train.shape[0])]
      )
      train.index.rename("ds", inplace=True)
      m = Prophet(stan_backend=backend)
      m.fit(train)
      assert np.all(m.history["ds"].values == train["ds"].values)
  
imports: import numpy
  import pandas
  import pytest
  from prophet import Prophet
  from prophet.utilities import warm_start_params
label_desc: Use image node_id 2 for calling the TestProphetDataPrep obj's underlying member method code with example usage: obj.test_setup_dataframe_ds_column(daily_univariate_ts, backend) without return types