WIP - Adds Machine to process a Statechart

This adds a test and functionality around processing the basic
Statechart in the first Statifier spec.

Relates #19

statifier-ex/lib/statifier/machine.ex

@@ -1,2 +1,29 @@
 defmodule Statifier.Machine do
+  @moduledoc """
+  A reactive system.
+
+  This corresponds to the SCXML Interpreter (also called SCXML Processor)
+  """
+
+  alias Statifier.{Statechart}
+
+  # This allows code to use the name of the module instead of __MODULE__
+  alias __MODULE__
+
+  # ID of a State
+  @type state_id :: String.t()
+
+  # The id(s) of the initial state(s) for the document.
+  # If not specified, the first child state in document order is used.
+  @type configuration :: [state_id]
+
+  @type t :: %Machine{
+          statechart: Statechart.t(),
+          configuration: configuration
+        }
+
+  defstruct statechart: nil,
+            configuration: []
+
+  def interpret(%Machine{} = machine), do: machine
 end

statifier-ex/test/statifier/machine_test.exs

@@ -1,2 +1,19 @@
 defmodule Statifier.MachineTest do
+  use ExUnit.Case
+
+  alias Statifier.{Machine, Statechart}
+
+  test "initial config of basic statechart" do
+    test_path = Path.join(File.cwd!(), "test/fixtures/basic.yml")
+
+    {:ok, test_config} = YamlElixir.read_from_file(test_path)
+
+    sc = Statechart.build(test_config["statechart"])
+
+    machine =
+      %Machine{statechart: sc}
+      |> Machine.interpret()
+
+    assert %Machine{configuration: ["greeting"]} = machine
+  end
 end