old_contents: import pytest
  
  import selfies as sf
  
  
  @pytest.fixture()
  def test_cases():
      return {
          "": (0, []),
          "[C][C][C]": (3, ["[C]", "[C]", "[C]"]),
          "[C].[C]": (3, ["[C]", ".", "[C]"]),
          "[C].[C][nop]": (4, ["[C]", ".", "[C]", "[nop]"]),
          "[C][epsilon][C]": (3, ["[C]", "[epsilon]", "[C]"])
      }
  
  
  @pytest.fixture()
  def test_cases_alphabet():
      return {'.', '[C]', '[nop]', '[epsilon]'}
  
  
  def test_len_selfies(test_cases):
      for s, (length, _) in test_cases.items():
          assert sf.len_selfies(s) == length
  
  
  def test_split_selfies(test_cases):
      for s, (_, symbols) in test_cases.items():
          assert list(sf.split_selfies(s)) == symbols
  
  
  def test_get_alphabet_from_selfies(test_cases, test_cases_alphabet):
      alphabet = sf.get_alphabet_from_selfies(test_cases.keys())
  
      assert alphabet == test_cases_alphabet
  
new_contents: import pytest
  
  import selfies as sf
  
  
  @pytest.fixture()
  def test_cases():
      return {
          "": (0, []),
          "[C][C][C]": (3, ["[C]", "[C]", "[C]"]),
          "[C].[C]": (3, ["[C]", ".", "[C]"]),
          "[C].[C][nop]": (4, ["[C]", ".", "[C]", "[nop]"]),
          "[C][epsilon][C]": (3, ["[C]", "[epsilon]", "[C]"])
      }
  
  
  @pytest.fixture()
  def test_cases_alphabet():
      return {'[C]', '[nop]', '[epsilon]'}
  
  
  def test_len_selfies(test_cases):
      for s, (length, _) in test_cases.items():
          assert sf.len_selfies(s) == length
  
  
  def test_split_selfies(test_cases):
      for s, (_, symbols) in test_cases.items():
          assert list(sf.split_selfies(s)) == symbols
  
  
  def test_get_alphabet_from_selfies(test_cases, test_cases_alphabet):
      alphabet = sf.get_alphabet_from_selfies(test_cases.keys())
  
      assert alphabet == test_cases_alphabet
  
subject: Update test_selfies_utils.py