Programming Elixir 1.6: exercise StringsAndBinaries-4

script.exs

ExUnit.start()

IO.puts(
  "------------------------------------------RESTART------------------------------------------"
)

defmodule This do
  # takes a single-quoted string of the form number [+-*/] number and returns
  # the result of the calculation. The individual numbers do not have leading
  # plus or minus signs.
  # calculate('123 + 27') # => 150
  def calculate(command) do
    [arg1, operator, arg2] =
      command
      |> List.to_string()
      |> String.split()
      |> Enum.zip([
        &String.to_integer/1,
        &String.to_atom/1,
        &String.to_integer/1
      ])
      |> Enum.map(fn {item, func} -> func.(item) end)

    apply(:erlang, operator, [arg1, arg2])
  end
end

defmodule AssertionTest do
  use ExUnit.Case, async: true

  test "calculate" do
    assert This.calculate('1 + 2') == 3
    assert This.calculate('1 + 0') == 1
    assert This.calculate('1 - 2') == -1
    assert This.calculate('1 * 2') == 2
    assert This.calculate('9 / 3') == 3
    assert This.calculate('9 / 3') == 3
  end
end