code: def test_core50_nc_benchmark(self):
      benchmark_instance = CORe50(scenario="nc")
      self.assertEqual(1, len(benchmark_instance.test_stream))
  
      classes_in_test = benchmark_instance.classes_in_experience[
          "test"
      ][0]
      self.assertSetEqual(set(range(50)), set(classes_in_test))
  
      # Regression tests for issue #774
      self.assertSequenceEqual(
          [10] + ([5] * 8), benchmark_instance.n_classes_per_exp
      )
      self.assertSetEqual(
          set(range(50)), set(benchmark_instance.classes_order)
      )
      self.assertEqual(50, len(benchmark_instance.classes_order))
  
imports: import unittest
  from avalanche.benchmarks.classic import CORe50
  from tests.unit_tests_utils import FAST_TEST, is_github_action
label_desc: Use image node_id 2 for calling the CORe50Test obj's underlying member method code with example usage: obj.test_core50_nc_benchmark() without return types