add branch listener functionaliy

have to store the branches and loop again as labels
dont neccessarily have positions yet

test/risc/position/helper.rb

@@ -37,6 +37,14 @@ module Risc
       DummyInstruction.new
     end
   end
+  class DummyBranch < Branch
+    attr_reader :precheck_called
+
+    def precheck
+      @precheck_called = true
+    end
+  end
+
   class DummyInstruction < Dummy
     include Util::List
     def initialize(nekst = nil)

test/risc/position/test_branch_listener.rb

@@ -1,14 +1,35 @@
 require_relative "helper"
+require 'minitest/mock'
 
 module Risc
-  class TestBranchListener < MiniTest::Test
+  class TestBranchListenerBooted < MiniTest::Test
+    def setup
+      DummyPlatform.boot
+      @binary = Parfait::BinaryCode.new(1)
+      @bin_pos = CodeListener.init(@binary).set(0)
+      @label = Label.new("HI","ho" , FakeAddress.new(2))
+      @branch = DummyBranch.new( "Dummy" , @label )
+      @branch.insert @label
+      InstructionListener.init(@branch , @binary)
+      @position = Position.get(@label)
+    end
+    def test_init_add_listener
+      assert_equal BranchListener , @position.event_table.values.first.last.class
+    end
+    def test_set
+      Position.get(@branch).set(12)
+      assert_equal 16 , Position.get(@label).at
+    end
+    def test_set_fires
+      Position.get(@label).set(20)
+      assert @branch.precheck_called
+    end
+  end
+  class TestBranchListenerPositioned < MiniTest::Test
     def setup
       @machine = Risc.machine.boot
       @machine.translate(:interpreter)
       @machine.position_all
     end
-
-    def test_has_init
-    end
   end
 end