introduce platform to abstract cpu and load address

test/risc/test_platform.rb

@@ -0,0 +1,25 @@
+require_relative "../helper"
+
+module Risc
+  class TestPlaform < MiniTest::Test
+
+    def test_factory_exists
+      assert Platform.for("Arm")
+    end
+    def test_factory_raise
+      assert_raises{ Platform.for("NotArm")}
+    end
+    def test_platform_class
+      arm = Platform.for("Arm")
+      assert_equal Arm::ArmPlatform , arm.class
+    end
+    def test_platform_translator_class
+      arm = Platform.for("Arm")
+      assert_equal Arm::Translator , arm.translator.class
+    end
+    def test_platform_loaded_class
+      arm = Platform.for("Arm")
+      assert_equal Fixnum , arm.loaded_at.class
+    end
+  end
+end