code: def test_min_train_series_length(self, mode):
      lgbm_cls = LightGBMModel if lgbm_available else XGBModel
      cb_cls = CatBoostModel if cb_available else XGBModel
      model = lgbm_cls(lags=4, multi_models=mode)
      min_train_series_length_expected = (
          -model.lags["target"][0] + model.output_chunk_length + 1
      )
      assert (
          min_train_series_length_expected
          == model.min_train_series_length
      )
      model = cb_cls(lags=2, multi_models=mode)
      min_train_series_length_expected = (
          -model.lags["target"][0] + model.output_chunk_length + 1
      )
      assert (
          min_train_series_length_expected
          == model.min_train_series_length
      )
      model = lgbm_cls(lags=[-4, -3, -2], multi_models=mode)
      min_train_series_length_expected = (
          -model.lags["target"][0] + model.output_chunk_length + 1
      )
      assert (
          min_train_series_length_expected
          == model.min_train_series_length
      )
      model = XGBModel(lags=[-4, -3, -2], multi_models=mode)
      min_train_series_length_expected = (
          -model.lags["target"][0] + model.output_chunk_length + 1
      )
      assert (
          min_train_series_length_expected
          == model.min_train_series_length
      )
  
imports: import copy
  import functools
  import itertools
  import math
  from unittest.mock import patch
  import numpy
  import pandas
  import pytest
  from sklearn.ensemble import HistGradientBoostingRegressor, RandomForestRegressor
  from sklearn.linear_model import LinearRegression
  import darts
  from darts import TimeSeries
  from darts.dataprocessing.encoders import FutureCyclicEncoder, PastDatetimeAttributeEncoder
  from darts.logging import get_logger
  from darts.metrics import mae, rmse
  from darts.models import CatBoostModel, LightGBMModel, LinearRegressionModel, NotImportedModule, RandomForest, RegressionModel, XGBModel
  from darts.utils import timeseries_generation
  from darts.utils.multioutput import MultiOutputRegressor
label_desc: Use image node_id 13 for calling the TestRegressionModels obj's underlying member method code with example usage: obj.test_min_train_series_length(mode) without return types