code: def test_ga_roulette_selection():
      new_ga = ga.GA()
  
      fitness = [10, 20, 30, 40, 50]
  
      idx = new_ga._roulette_selection(len(fitness), fitness)
  
      assert len(idx) == 4
  
file_path: opytimizer/tests/opytimizer/optimizers/evolutionary/test_ga.py
imports: import numpy
  from opytimizer.optimizers.evolutionary import ga
  from opytimizer.spaces import search
label_desc: Use image node_id 3 for calling a global function with example usage: test_ga_roulette_selection() without return types