docstr: Test that all flattened params are returned if None
docstr_tok: ["Test","that","all","flattened","params","are","returned","if","None"]
code: def test_flat_no_params(self, hspace, flat_params):
      """Test that all flattened params are returned if None"""
      assert flatten_params(hspace) == flat_params
  
imports: import numpy
  import pandas
  import pytest
  from sklearn.ensemble import AdaBoostRegressor, BaggingRegressor, ExtraTreesRegressor, GradientBoostingRegressor, RandomForestRegressor
  from orion.analysis.base import average, flatten_numpy, flatten_params, ranking, to_numpy, train_regressor
  from orion.core.io.space_builder import SpaceBuilder
  from orion.core.worker.transformer import build_required_space
label_desc: Use image node_id 2 for calling the TestFlattenParams obj's underlying member method code with example usage: obj.test_flat_no_params(hspace, flat_params) without return types