Elixir doctest fails for function that returns random values

I have a function in Elixir that produces three random RGB tuples in a list.

defmodule Color do



  @doc """
  Create three random r,g,b colors as a list of three tuples

  ## Examples

      iex> colors = Color.pick_color()
      iex> colors
      [{207, 127, 117}, {219, 121, 237}, {109, 101, 206}]

  """
      def pick_color() do
        color = Enum.map((0..2), fn(x)->
          r = Enum.random(0..255)
          g = Enum.random(0..255)
          b = Enum.random(0..255)
          {r, g, b}
        end)
end

When I run my tests, my doctests fail. The resulting list of tuples are different than what is defined in my doctest. How can I write a doctest for a function that returns a random value?