Metaprogramming

Generate tests at compile time

defmodule ATest do
  use ExUnit.Case

  [{1, 2, 3}, {10, 20, 40}, {100, 200, 300}]
  |> Enum.each(fn {a, b, c} ->
    test "#{a} + #{b} = #{c}" do
      assert unquote(a) + unquote(b) = unquote(c)
    end
  end)
end

Output:

.

  1) test 10 + 20 = 40 (Test.Test)
     test.exs:6
     match (=) failed
     code: 10 + 20 = 40
     rhs:  40
     stacktrace:
       test.exs:7

.

Finished in 0.1 seconds (0.1s on load, 0.00s on tests)
3 tests, 1 failure