code: def test_input_validation(df):
      """Tests input validation"""
      with pytest.raises(
          ValueError, match="`coverage` must be provided"
      ):
          UnivariateForecast(
              df,
              train_end_date=datetime.datetime(2018, 1, 2),
              coverage=None,
          )
  
      with pytest.raises(
          ValueError, match="`coverage` must be between 0.0 and 1.0"
      ):
          UnivariateForecast(
              df,
              train_end_date=datetime.datetime(2018, 1, 2),
              coverage=80.0,
          )
  
      with pytest.raises(
          ValueError, match="2018-01-05 is not found in time column"
      ):
          UnivariateForecast(df, train_end_date="2018-01-05")
  
      with pytest.raises(
          ValueError, match="Column not found in data frame"
      ):
          UnivariateForecast(df, actual_col="not_a_column")
  
imports: import datetime
  import math
  import sys
  from functools import partial
  import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
  from pandas.testing import assert_series_equal
  from sklearn.pipeline import Pipeline
  from greykite.common import constants
  from greykite.common.evaluation import ElementwiseEvaluationMetricEnum
  from greykite.common.evaluation import EvaluationMetricEnum
  from greykite.common.python_utils import assert_equal
  from greykite.common.testing_utils import gen_sliced_df
  from greykite.framework.input.univariate_time_series import UnivariateTimeSeries
  from greykite.framework.output.univariate_forecast import UnivariateForecast
  from greykite.framework.pipeline.utils import get_forecast
  from greykite.sklearn.estimator.prophet_estimator import ProphetEstimator
  from greykite.sklearn.estimator.silverkite_estimator import SilverkiteEstimator
  from greykite.sklearn.estimator.testing_utils import params_component_breakdowns
label_desc: Use image node_id 6 for calling a global function with example usage: test_input_validation(df) without return types