code: def test_optimizer():
      """Tests ``Optimizer`` class."""
      optimizer = Optimizer()
      assert optimizer.reward is None
      assert optimizer.fit_info == {"param_full": None}
  
file_path: greykite/greykite/tests/detection/detector/test_optimizer.py
imports: import numpy
  import pandas
  from greykite.common.viz.timeseries_annotate import plot_lines_markers
  from greykite.detection.detector.optimizer import CalcResult
  from greykite.detection.detector.optimizer import Optimizer
  from greykite.detection.detector.reward import Reward
label_desc: Use image node_id 1 for calling a global function with example usage: test_optimizer() without return types