random_test.exs

defmodule RandomTest do
  use ExUnit.Case

  test "randomness may be seeded" do
    seed = :rand.export_seed()
    list = Enum.to_list(1..10_000)

    values =
      for _ <- 1..10_000 do
        Enum.random(list)
        |> tap(fn _ -> :rand.seed(seed) end)
      end

    assert values |> Enum.uniq() |> length == 1
  end
end