Property-Based Testing with PropEr, Erlang, and Elixir

State Machine Properties

Modeling the Circuit Breaker

First, the shim module:

Elixir                 code/FSMProperties/elixir/circuit/test/break_shim.ex

defmodule BreakShim do
  @service :test_service

  def success() do
    :circuit_breaker.call(
      @service,
      fn -> :success end,
      :timer.hours(1),

    fn -> true end,
    :timer.hours(1),
    options()
  )
end

def err(reason) do
  :circuit_breaker.call(
    @service,
    fn -> {:error, reason} end,
    :timer.hours(1),
    fn -> true end,
    :timer.hours(1),
    options()
  )
end

def ignored_error(reason), do: err(reason)

def timeout() do
  :circuit_breaker.call(
    @service,
    fn -> :timer.sleep(:infinity) end, 
    0,
    fn -> true end,
  ...