code: def test_custom_scaler(self):
      # invalid scaler with missing inverse_transform
      class InvalidScaler:
          def fit(self):
              pass
  
          def transform(self):
              pass
  
      with pytest.raises(ValueError):
          _ = StaticCovariatesTransformer(
              transformer_num=InvalidScaler()
          )
  
      with pytest.raises(ValueError):
          _ = StaticCovariatesTransformer(
              transformer_cat=InvalidScaler()
          )
  
      class ValidScaler(InvalidScaler):
          def inverse_transform(self):
              pass
  
      _ = StaticCovariatesTransformer(transformer_num=ValidScaler())
      _ = StaticCovariatesTransformer(transformer_cat=ValidScaler())
      _ = StaticCovariatesTransformer(
          transformer_num=ValidScaler(), transformer_cat=ValidScaler()
      )
  
file_path: darts/darts/tests/dataprocessing/transformers/test_static_covariates_transformer.py
imports: import numpy
  import pandas
  import pytest
  from sklearn.preprocessing import MinMaxScaler, OneHotEncoder
  from darts import TimeSeries
  from darts.dataprocessing.transformers import StaticCovariatesTransformer
  from darts.utils import timeseries_generation
label_desc: Use image node_id 4 for calling the TestStaticCovariatesTransformer obj's underlying member method code with example usage: obj.test_custom_scaler() without return types