diff --git a/Gemfile.lock b/Gemfile.lock
index bc400ce..b0b2aaa 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,6 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     SgfParser (2.0.0)
+    ray (0.2.1)
 
 PLATFORMS
   java
@@ -9,3 +10,4 @@ PLATFORMS
 
 DEPENDENCIES
   SgfParser
+  ray
diff --git a/lib/weiqi.rb b/lib/weiqi.rb
index 61f8edf..27984c5 100644
--- a/lib/weiqi.rb
+++ b/lib/weiqi.rb
@@ -1,3 +1,4 @@
 require_relative "weiqi/board"
 require_relative "weiqi/gnu_go"
+require_relative "weiqi/scheduler"
 require_relative "weiqi/game"
diff --git a/lib/weiqi/game.rb b/lib/weiqi/game.rb
index 183efe8..f3ca1e3 100644
--- a/lib/weiqi/game.rb
+++ b/lib/weiqi/game.rb
@@ -1,12 +1,10 @@
-require "thread"
-
 module Weiqi
   class Game
-    def initialize(engine)
+    def initialize(engine, scheduler=Weiqi::AsyncScheduler.new)
       self.engine    = engine
       self.observers = []
       self.history   = []
-      self.mutex     = Mutex.new
+      self.scheduler = scheduler
     end
 
     def observe(&block)
@@ -27,17 +25,13 @@ def quit
 
     private
 
-    attr_accessor :engine, :observers, :history, :mutex
+    attr_accessor :engine, :observers, :history, :scheduler
     
     def move
-      return if mutex.locked?
-
-      Thread.new do 
-        mutex.synchronize do
-          notify_observers(yield)
+      scheduler.run do
+        notify_observers(yield)
 
-          notify_observers(engine.play_white) 
-        end
+        notify_observers(engine.play_white) 
       end
     end
 
diff --git a/lib/weiqi/scheduler.rb b/lib/weiqi/scheduler.rb
new file mode 100644
index 0000000..5518356
--- /dev/null
+++ b/lib/weiqi/scheduler.rb
@@ -0,0 +1,21 @@
+require "thread"
+
+module Weiqi
+  class SequentialScheduler
+    def run
+      yield
+    end
+  end
+
+  class AsyncScheduler
+    def initialize
+      @mutex = Mutex.new
+    end
+
+    def run(&block)
+      return if @mutex.locked?
+
+      @mutex.synchronize { yield }
+    end
+  end
+end
diff --git a/test/game_test.rb b/test/game_test.rb
new file mode 100644
index 0000000..20c96b7
--- /dev/null
+++ b/test/game_test.rb
@@ -0,0 +1,42 @@
+require "minitest/autorun"
+require "mocha/mini_test"
+
+require_relative "../lib/weiqi"
+require_relative "helpers/game_session"
+
+describe "Game" do
+  let(:engine)     { mock("Engine") }
+  let(:game)       { Weiqi::Game.new(engine, Weiqi::SequentialScheduler.new) }
+  let(:session)    { GameSession.new(engine, game) }
+  let(:transcript) { [] }
+
+  it "must be able to end game end by passing" do
+    assert_output "PASS!\nGame over. Final score 0\n" do
+      session.black_passes
+             .white_passes
+             .final_score(0)
+             .game_ends
+    end
+  end
+
+  it "must be able to end game by resignation" do
+    assert_output "PASS!\nYou win! The computer resigned\n" do
+      session.black_passes
+             .white_resigns
+             .game_ends
+    end
+  end
+
+  it "must be able to notify observers of moves" do
+   moves = []
+   game.observe { |board| moves << board.last_move }
+   
+   session.black_plays(3,3)
+          .white_plays(3,4)
+          .black_plays(4,4)
+          .white_plays(5,5)
+          .verify_results
+
+    moves.must_equal([[3,3],[3,4],[4,4],[5,5]])
+  end
+end
diff --git a/test/helpers/game_session.rb b/test/helpers/game_session.rb
new file mode 100644
index 0000000..e23c5ec
--- /dev/null
+++ b/test/helpers/game_session.rb
@@ -0,0 +1,69 @@
+class GameSession
+  def initialize(mock_engine, game)
+    @moves   = Mocha::Sequence.new('moves')
+    @engine  = mock_engine
+    @game    = game
+
+    @actions = []
+  end
+
+  def black_passes
+    @engine.expects(:pass_black).in_sequence(@moves).returns(move("PASS"))
+
+    @actions << lambda { @game.pass }
+
+    self
+  end
+
+  def black_plays(x,y)
+    @engine.expects(:play_black).in_sequence(@moves).returns(move([x,y]))
+
+    @actions << lambda { @game.play(x, y) }
+
+    self
+  end
+
+  def white_plays(x,y)
+    @engine.expects(:play_white).in_sequence(@moves).returns(move([x,y]))
+
+    self
+  end
+
+  def white_passes
+    @engine.expects(:play_white).in_sequence(@moves).returns(move("PASS"))
+
+    self
+  end
+
+  def white_resigns
+    @engine.expects(:play_white).in_sequence(@moves).returns(move("resign"))
+
+    self
+  end
+
+  def final_score(num)
+    @engine.expects(:final_score).returns(num)
+
+    self
+  end
+
+  def game_ends
+    @engine.expects(:quit)
+
+    verify_results
+
+    self
+  end
+
+  def verify_results
+    @actions.each { |a| a.call }
+
+    self
+  end
+
+  private
+
+  def move(data)
+    Struct.new(:last_move).new(data)
+  end
+end