code: def test_init(params):
      """Tests initialization"""
      model = ConstantBaseForecastEstimator(**params)
      assert model.score_func == mean_absolute_error
      assert model.coverage == 0.9
      assert model.null_model_params == params["null_model_params"]
      assert model.null_model is None
      assert model.time_col_ is None
      assert model.value_col_ is None
  
      # set_params must be able to replicate the init
      model2 = ConstantBaseForecastEstimator()
      model2.set_params(**params)
      assert model2.__dict__ == model.__dict__
  
      model = ConstantBaseForecastEstimator()
      assert model.score_func == mean_squared_error
      assert model.coverage == 0.95
      assert model.null_model_params is None
      assert model.null_model is None
      assert model.time_col_ is None
      assert model.value_col_ is None
  
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
  from sklearn.metrics import mean_absolute_error
  from sklearn.metrics import mean_squared_error
  from testfixtures import LogCapture
  from greykite.common.constants import LOGGER_NAME
  from greykite.common.constants import PREDICTED_COL
  from greykite.common.constants import PREDICTED_LOWER_COL
  from greykite.common.constants import PREDICTED_UPPER_COL
  from greykite.common.constants import TIME_COL
  from greykite.common.constants import VALUE_COL
  from greykite.common.evaluation import r2_null_model_score
  from greykite.sklearn.estimator.base_forecast_estimator import BaseForecastEstimator
  from greykite.sklearn.uncertainty.uncertainty_methods import UncertaintyMethodEnum
label_desc: Use image node_id 5 for calling a global function with example usage: test_init(params) without return types