func test_memory_generateConstPlayfield() -> String {
  let idGroups = memory_generateConstPlayfield(2)
  if (
    idGroups.count == 4 &&
    idGroups[0] == 0 &&
    idGroups[1] == 0 &&
    idGroups[2] == 1 &&
    idGroups[3] == 1
  ) {
    return "OK: memory_generateConstPlayfield"
  }

  return "ERR: memory_generateConstPlayfield"
}