code: def test_get_fit_params():
      """Tests get_fit_params"""
      params = get_fit_params(method="custom")
      assert params == {}
  
      params = get_fit_params(method="bottom_up")
      assert params == {}
  
      params = get_fit_params(method="ols")
      assert params["unbiased"]
      assert params["lam_var"] == 1.0
      assert params["covariance"] == "identity"
  
      params = get_fit_params(method="mint_sample")
      assert params["unbiased"]
      assert params["lam_var"] == 1.0
      assert params["covariance"] == "sample"
  
      with pytest.raises(
          ValueError,
          match="`method` 'unknown' is not recognized. "
          "Must be one of 'bottom_up', 'ols', 'mint_sample', 'custom'",
      ):
          get_fit_params(method="unknown")
  
imports: import math
  import os
  import warnings
  import cvxpy
  import numpy
  import pandas
  import pytest
  from scipy.linalg import sqrtm
  from sklearn.exceptions import NotFittedError
  from greykite.algo.reconcile.convex.reconcile_forecasts import ReconcileAdditiveForecasts
  from greykite.algo.reconcile.convex.reconcile_forecasts import TraceInfo
  from greykite.algo.reconcile.convex.reconcile_forecasts import apply_method_defaults
  from greykite.algo.reconcile.convex.reconcile_forecasts import evaluation_plot
  from greykite.algo.reconcile.convex.reconcile_forecasts import get_fit_params
  from greykite.algo.reconcile.convex.reconcile_forecasts import get_weight_matrix
  from greykite.algo.reconcile.hierarchical_relationship import HierarchicalRelationship
  from greykite.common.constants import TIME_COL
  from greykite.common.data_loader import DataLoader
  from greykite.common.evaluation import mean_absolute_percent_error
  from greykite.common.evaluation import median_absolute_percent_error
  from greykite.common.evaluation import root_mean_squared_error
  from greykite.common.python_utils import assert_equal
  from greykite.common.python_utils import reorder_columns
label_desc: Use image node_id 3 for calling a global function with example usage: test_get_fit_params() without return types