def deps do
  [{:cabbage, "~> 0.4.0"}]
end

config :cabbage, features: "some/other/path/from/your/project/root"

defmodule MyApp.Features.CoffeeTest do
  # Options, other than file:, are passed directly to `ExUnit`
  use Cabbage.Feature, async: false, file: "coffee.feature"

  # `setup_all/1` provides a callback for doing something before the entire suite runs
  # As below, `setup/1` provides means of doing something prior to each scenario
  setup do
    on_exit fn -> # Do something when the scenario is done
      IO.puts "Scenario completed, cleanup stuff"
    end
    %{my_starting: :state, user: %User{}} # Return some beginning state
  end

  # All `defgiven/4`, `defwhen/4` and `defthen/4` takes a regex, matched data, state and lastly a block
  defgiven ~r/^there (is|are) (?<number>\d+) coffee(s) left in the machine$/, %{number: number}, %{user: user} do
    # `{:ok, state}` gets returned from each callback which updates the state or
    # leaves the state unchanged when something else is returned
    {:ok, %{machine: Machine.put_coffee(Machine.new, number)}}
  end

  defgiven ~r/^I have deposited £(?<number>\d+)$/, %{number: number}, %{user: user, machine: machine} do
    {:ok, %{machine: Machine.deposit(machine, user, number)}} # State is automatically merged so this won't erase `user`
  end

  # With no matches, the map is empty. Since state is unchanged, its not necessary to return it
  defwhen ~r/^I press the coffee button$/, _, state do
    Machine.press_coffee(state.machine) # instead would be some `hound` or `wallaby` dsl
  end

  # Since state is unchanged, its not necessary to return it
  defthen ~r/^I should be served a coffee$/, _, state do
    assert %Coffee{} = Machine.take_drink(state.machine) # Make your `assert`ions in `defthen/4`s
  end
end

defmodule MyApp.Features.CoffeeTest do
  use ExUnit.Case, async: false

  setup do
    on_exit fn ->
      IO.puts "Scenario completed, cleanup stuff"
    end
    {:ok, %{my_starting: :state, user: %User{}}}
  end

  # Each scenario would generate a single test case
  @tag :integration
  test "Buy last coffee", %{my_starting: :state, user: user} do
    # From the given
    state = %{user: user, machine: Machine.put_coffee(Machine.new, number)}
    # From the and
    state = Map.put(state, :machine, Machine.deposit(machine, user, number))
    # From the when
    Machine.press_coffee(state.machine)
    # From the then
    assert %Coffee{} = Machine.take_drink(state.machine)
  end
end