From 2e9cd7ac29721c31ab00e56601765727aea68322 Mon Sep 17 00:00:00 2001
From: Kye Wei <kye.wei@shopify.com>
Date: Thu, 12 Nov 2015 16:32:39 +0000
Subject: [PATCH] Change to State from Enum, updated to match merged PR,
 removed Mutex code

---
 lib/semian.rb                       | 29 ++-------------
 lib/semian/circuit_breaker.rb       | 28 ++++++---------
 lib/semian/shared_memory_object.rb  |  2 --
 lib/semian/simple_enum.rb           | 42 ----------------------
 lib/semian/simple_integer.rb        |  2 --
 lib/semian/simple_sliding_window.rb |  3 --
 lib/semian/simple_state.rb          | 45 +++++++++++++++++++++++
 lib/semian/sysv_enum.rb             | 10 ------
 lib/semian/sysv_state.rb            | 56 +++++++++++++++++++++++++++++
 test/circuit_breaker_test.rb        |  2 +-
 test/simple_enum_test.rb            | 47 ------------------------
 test/simple_state_test.rb           | 45 +++++++++++++++++++++++
 test/sysv_enum_test.rb              | 49 -------------------------
 test/sysv_integer_test.rb           | 32 +++--------------
 test/sysv_sliding_window_test.rb    | 43 ++++++----------------
 test/sysv_state_test.rb             | 44 +++++++++++++++++++++++
 16 files changed, 218 insertions(+), 261 deletions(-)
 delete mode 100644 lib/semian/simple_enum.rb
 create mode 100644 lib/semian/simple_state.rb
 delete mode 100644 lib/semian/sysv_enum.rb
 create mode 100644 lib/semian/sysv_state.rb
 delete mode 100644 test/simple_enum_test.rb
 create mode 100644 test/simple_state_test.rb
 delete mode 100644 test/sysv_enum_test.rb
 create mode 100644 test/sysv_state_test.rb

diff --git a/lib/semian.rb b/lib/semian.rb
index 90f8a507..c16ff802 100644
--- a/lib/semian.rb
+++ b/lib/semian.rb
@@ -150,31 +150,6 @@ def destroy(name)
   def resources
     @resources ||= {}
   end
-
-  module ReentrantMutex
-    attr_reader :mutex
-
-    def call_with_mutex
-      @mutex ||= Monitor.new
-      @mutex.synchronize do
-        yield if block_given?
-      end
-    end
-
-    def self.included(base)
-      def base.surround_with_mutex(*names)
-        names.each do |name|
-          new_name = "#{name}_inner".freeze
-          alias_method new_name, name
-          define_method(name) do |*args, &block|
-            call_with_mutex do
-              method(new_name).call(*args, &block)
-            end
-          end
-        end
-      end
-    end
-  end
 end
 
 require 'semian/resource'
@@ -185,10 +160,10 @@ def base.surround_with_mutex(*names)
 require 'semian/shared_memory_object'
 require 'semian/simple_sliding_window'
 require 'semian/simple_integer'
-require 'semian/simple_enum'
+require 'semian/simple_state'
 require 'semian/sysv_sliding_window'
 require 'semian/sysv_integer'
-require 'semian/sysv_enum'
+require 'semian/sysv_state'
 if Semian.semaphores_enabled?
   require 'semian/semian'
 else
diff --git a/lib/semian/circuit_breaker.rb b/lib/semian/circuit_breaker.rb
index 27174a96..b6567314 100644
--- a/lib/semian/circuit_breaker.rb
+++ b/lib/semian/circuit_breaker.rb
@@ -1,5 +1,7 @@
 module Semian
   class CircuitBreaker #:nodoc:
+    extend Forwardable
+
     def initialize(name, exceptions:, success_threshold:, error_threshold:, error_timeout:, permissions:, implementation:)
       @name = name.to_s
       @success_count_threshold = success_threshold
@@ -12,9 +14,8 @@ def initialize(name, exceptions:, success_threshold:, error_threshold:, error_ti
                                                   permissions: permissions)
       @successes = implementation::Integer.new(name: "#{name}_sysv_integer",
                                                permissions: permissions)
-      @state = implementation::Enum.new(symbol_list: [:closed, :half_open, :open],
-                                        name: "#{name}_sysv_enum",
-                                        permissions: permissions)
+      @state = implementation::State.new(name: "#{name}_sysv_state",
+                                         permissions: permissions)
     end
 
     def acquire
@@ -67,33 +68,24 @@ def destroy
 
     private
 
-    def closed?
-      @state.value == :closed
-    end
+    def_delegators :@state, :closed?, :open?, :half_open?
+    private :closed?, :open?, :half_open?
 
     def close
       log_state_transition(:closed)
-      @state.value = :closed
+      @state.close
       @errors.clear
     end
 
-    def open?
-      @state.value == :open
-    end
-
     def open
       log_state_transition(:open)
-      @state.value = :open
-    end
-
-    def half_open?
-      @state.value == :half_open
+      @state.open
     end
 
     def half_open
       log_state_transition(:half_open)
-      @state.value = :half_open
-      @successes.value = 0
+      @state.half_open
+      @successes.reset
     end
 
     def success_threshold_reached?
diff --git a/lib/semian/shared_memory_object.rb b/lib/semian/shared_memory_object.rb
index 660cc1c0..bad3433f 100644
--- a/lib/semian/shared_memory_object.rb
+++ b/lib/semian/shared_memory_object.rb
@@ -1,7 +1,5 @@
 module Semian
   class SharedMemoryObject #:nodoc:
-    include ReentrantMutex
-
     @type_size = {}
     def self.sizeof(type)
       size = (@type_size[type.to_sym] ||= (respond_to?(:_sizeof) ? _sizeof(type.to_sym) : 0))
diff --git a/lib/semian/simple_enum.rb b/lib/semian/simple_enum.rb
deleted file mode 100644
index 7f6ab740..00000000
--- a/lib/semian/simple_enum.rb
+++ /dev/null
@@ -1,42 +0,0 @@
-require 'forwardable'
-
-module Semian
-  module Simple
-    class Enum < SharedMemoryObject #:nodoc:
-      extend Forwardable
-
-      def_delegators :@integer, :semid, :shmid, :execute_atomically, :transaction,
-                     :shared?, :destroy, :acquire_memory_object, :bind_init_fn
-      private :shared?, :acquire_memory_object, :bind_init_fn
-
-      def initialize(symbol_list:)
-        @integer = Semian::Simple::Integer.new
-        initialize_lookup(symbol_list)
-      end
-
-      def increment(val = 1)
-        @integer.value = (@integer.value + val) % @sym_to_num.size
-        value
-      end
-
-      def value
-        @num_to_sym.fetch(@integer.value)
-      end
-
-      def value=(sym)
-        @integer.value = @sym_to_num.fetch(sym)
-      end
-
-      private
-
-      def initialize_lookup(symbol_list)
-        # Assume symbol_list[0] is mapped to 0
-        # Cannot just use #object_id since #object_id for symbols is different in every run
-        # For now, implement a C-style enum type backed by integers
-
-        @sym_to_num = Hash[symbol_list.each_with_index.to_a]
-        @num_to_sym = @sym_to_num.invert
-      end
-    end
-  end
-end
diff --git a/lib/semian/simple_integer.rb b/lib/semian/simple_integer.rb
index 8778681a..ea27d6eb 100644
--- a/lib/semian/simple_integer.rb
+++ b/lib/semian/simple_integer.rb
@@ -22,8 +22,6 @@ def destroy
           @value = 0
         end
       end
-
-      surround_with_mutex :value, :value=, :increment
     end
   end
 end
diff --git a/lib/semian/simple_sliding_window.rb b/lib/semian/simple_sliding_window.rb
index 0efe8137..e551c8f6 100644
--- a/lib/semian/simple_sliding_window.rb
+++ b/lib/semian/simple_sliding_window.rb
@@ -42,9 +42,6 @@ def destroy
           clear
         end
       end
-
-      surround_with_mutex :size, :pop, :shift, :first, :last, :max_size,
-                          :resize_to, :<<, :push, :clear
     end
   end
 end
diff --git a/lib/semian/simple_state.rb b/lib/semian/simple_state.rb
new file mode 100644
index 00000000..59d6774a
--- /dev/null
+++ b/lib/semian/simple_state.rb
@@ -0,0 +1,45 @@
+require 'forwardable'
+
+module Semian
+  module Simple
+    class State < SharedMemoryObject #:nodoc:
+      def initialize
+        reset
+      end
+
+      attr_reader :value
+
+      def open?
+        value == :open
+      end
+
+      def closed?
+        value == :closed
+      end
+
+      def half_open?
+        value == :half_open
+      end
+
+      def open
+        @value = :open
+      end
+
+      def close
+        @value = :closed
+      end
+
+      def half_open
+        @value = :half_open
+      end
+
+      def reset
+        close
+      end
+
+      def destroy
+        reset
+      end
+    end
+  end
+end
diff --git a/lib/semian/sysv_enum.rb b/lib/semian/sysv_enum.rb
deleted file mode 100644
index 6122eb65..00000000
--- a/lib/semian/sysv_enum.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-module Semian
-  module SysV
-    class Enum < Semian::Simple::Enum #:nodoc:
-      def initialize(symbol_list:, name:, permissions:)
-        @integer = Semian::SysV::Integer.new(name: name, permissions: permissions)
-        initialize_lookup(symbol_list)
-      end
-    end
-  end
-end
diff --git a/lib/semian/sysv_state.rb b/lib/semian/sysv_state.rb
new file mode 100644
index 00000000..2d0f4568
--- /dev/null
+++ b/lib/semian/sysv_state.rb
@@ -0,0 +1,56 @@
+module Semian
+  module SysV
+    class State < Semian::Simple::State #:nodoc:
+      extend Forwardable
+
+      def_delegators :@integer, :semid, :shmid, :execute_atomically, :transaction,
+                     :shared?, :acquire_memory_object, :bind_init_fn
+      private :shared?, :acquire_memory_object, :bind_init_fn
+
+      def initialize(name:, permissions:)
+        @integer = Semian::SysV::Integer.new(name: name, permissions: permissions)
+        initialize_lookup([:closed, :open, :half_open])
+      end
+
+      def open
+        self.value = :open
+      end
+
+      def close
+        self.value = :closed
+      end
+
+      def half_open
+        self.value = :half_open
+      end
+
+      def reset
+        close
+      end
+
+      def destroy
+        reset
+        @integer.destroy
+      end
+
+      def value
+        @num_to_sym.fetch(@integer.value) { raise ArgumentError }
+      end
+
+      private
+
+      def value=(sym)
+        @integer.value = @sym_to_num.fetch(sym) { raise ArgumentError }
+      end
+
+      def initialize_lookup(symbol_list)
+        # Assume symbol_list[0] is mapped to 0
+        # Cannot just use #object_id since #object_id for symbols is different in every run
+        # For now, implement a C-style enum type backed by integers
+
+        @sym_to_num = Hash[symbol_list.each_with_index.to_a]
+        @num_to_sym = @sym_to_num.invert
+      end
+    end
+  end
+end
diff --git a/test/circuit_breaker_test.rb b/test/circuit_breaker_test.rb
index 305c31b0..e79964eb 100644
--- a/test/circuit_breaker_test.rb
+++ b/test/circuit_breaker_test.rb
@@ -138,7 +138,7 @@ def test_shared_fresh_worker_killed_should_not_reset_circuit_breaker_data
     Process.waitall
     fork do
       Semian.register(:unique_res, tickets: 1, exceptions: [SomeError], error_threshold: 2, error_timeout: 5, success_threshold: 1)
-      assert_circuit_opened
+      assert_circuit_opened Semian[:unique_res]
     end
 
     Process.waitall
diff --git a/test/simple_enum_test.rb b/test/simple_enum_test.rb
deleted file mode 100644
index 6846a6dc..00000000
--- a/test/simple_enum_test.rb
+++ /dev/null
@@ -1,47 +0,0 @@
-require 'test_helper'
-
-class TestSimpleEnum < MiniTest::Unit::TestCase
-  CLASS = ::Semian::Simple::Enum
-
-  def setup
-    @enum = CLASS.new(symbol_list: [:one, :two, :three])
-  end
-
-  def teardown
-    @enum.destroy
-  end
-
-  module EnumTestCases
-    def test_assigning
-      old = @enum.value
-      @enum.value = @enum.value
-      assert_equal old, @enum.value
-      @enum.value = :two
-      assert_equal :two, @enum.value
-    end
-
-    def test_iterate_enum
-      @enum.value = :one
-      @enum.increment
-      assert_equal :two, @enum.value
-      @enum.increment
-      assert_equal :three, @enum.value
-      @enum.increment
-      assert_equal :one, @enum.value
-      @enum.increment(2)
-      assert_equal :three, @enum.value
-      @enum.increment(4)
-      assert_equal :one, @enum.value
-      @enum.increment(0)
-      assert_equal :one, @enum.value
-    end
-
-    def test_will_throw_error_when_invalid_symbol_given
-      assert_raises KeyError do
-        @enum.value = :four
-      end
-    end
-  end
-
-  include EnumTestCases
-end
diff --git a/test/simple_state_test.rb b/test/simple_state_test.rb
new file mode 100644
index 00000000..edab7c22
--- /dev/null
+++ b/test/simple_state_test.rb
@@ -0,0 +1,45 @@
+require 'test_helper'
+
+class TestSimpleState < MiniTest::Unit::TestCase
+  CLASS = ::Semian::Simple::State
+
+  def setup
+    @state = CLASS.new
+  end
+
+  def teardown
+    @state.destroy
+  end
+
+  module StateTestCases
+    def test_start_closed?
+      assert @state.closed?
+    end
+
+    def test_open
+      @state.open
+      assert @state.open?
+      assert_equal @state.value, :open
+    end
+
+    def test_close
+      @state.close
+      assert @state.closed?
+      assert_equal @state.value, :closed
+    end
+
+    def test_half_open
+      @state.half_open
+      assert @state.half_open?
+      assert_equal @state.value, :half_open
+    end
+
+    def test_reset
+      @state.reset
+      assert @state.closed?
+      assert_equal @state.value, :closed
+    end
+  end
+
+  include StateTestCases
+end
diff --git a/test/sysv_enum_test.rb b/test/sysv_enum_test.rb
deleted file mode 100644
index ecf64784..00000000
--- a/test/sysv_enum_test.rb
+++ /dev/null
@@ -1,49 +0,0 @@
-require 'test_helper'
-
-class TestSysVEnum < MiniTest::Unit::TestCase
-  # Emulate sharedness to test correctness against real SysVAtomicEnum class
-  class FakeSysVAtomicEnum < Semian::Simple::Enum
-    class << self
-      attr_accessor :resources
-    end
-    self.resources = {}
-    attr_accessor :name
-    def self.new(symbol_list:, name:, permissions:)
-      obj = resources[name] ||= super
-      obj.name = name
-      obj
-    end
-
-    def destroy
-      self.class.resources.delete(@name)
-    end
-
-    def shared?
-      true
-    end
-  end
-
-  CLASS = ::Semian::SysV::Enum
-
-  def setup
-    @enum = CLASS.new(symbol_list: [:one, :two, :three],
-                      name: 'TestAtomicEnum',
-                      permissions: 0660)
-  end
-
-  def teardown
-    @enum.destroy
-  end
-
-  include TestSimpleEnum::EnumTestCases
-
-  def test_memory_is_shared
-    assert_equal :one, @enum.value
-    @enum.value = :three
-
-    enum_2 = CLASS.new(symbol_list: [:one, :two, :three],
-                       name: 'TestAtomicEnum',
-                       permissions: 0660)
-    assert_equal :three, enum_2.value
-  end
-end
diff --git a/test/sysv_integer_test.rb b/test/sysv_integer_test.rb
index a36bc653..c445193d 100644
--- a/test/sysv_integer_test.rb
+++ b/test/sysv_integer_test.rb
@@ -1,32 +1,10 @@
 require 'test_helper'
 
 class TestSysVInteger < MiniTest::Unit::TestCase
-  # Emulate sharedness to test correctness against real SysVAtomicInteger class
-  class FakeSysVAtomicInteger < Semian::Simple::Integer
-    class << self
-      attr_accessor :resources
-    end
-    self.resources = {}
-    attr_accessor :name
-    def self.new(name:, permissions:)
-      obj = resources[name] ||= super
-      obj.name = name
-      obj
-    end
-
-    def destroy
-      self.class.resources.delete(@name)
-    end
-
-    def shared?
-      true
-    end
-  end
-
   CLASS = ::Semian::SysV::Integer
 
   def setup
-    @integer = CLASS.new(name: 'TestAtomicInteger', permissions: 0660)
+    @integer = CLASS.new(name: 'TestSysVInteger', permissions: 0660)
     @integer.value = 0
   end
 
@@ -37,7 +15,7 @@ def teardown
   include TestSimpleInteger::IntegerTestCases
 
   def test_memory_is_shared
-    integer_2 = CLASS.new(name: 'TestAtomicInteger', permissions: 0660)
+    integer_2 = CLASS.new(name: 'TestSysVInteger', permissions: 0660)
     integer_2.value = 100
     assert_equal 100, @integer.value
     @integer.value = 200
@@ -48,10 +26,10 @@ def test_memory_is_shared
 
   def test_memory_not_reset_when_at_least_one_worker_using_it
     @integer.value = 109
-    integer_2 = CLASS.new(name: 'TestAtomicInteger', permissions: 0660)
+    integer_2 = CLASS.new(name: 'TestSysVInteger', permissions: 0660)
     assert_equal @integer.value, integer_2.value
     pid = fork do
-      integer_3 = CLASS.new(name: 'TestAtomicInteger', permissions: 0660)
+      integer_3 = CLASS.new(name: 'TestSysVInteger', permissions: 0660)
       assert_equal 109, integer_3.value
       sleep
     end
@@ -59,7 +37,7 @@ def test_memory_not_reset_when_at_least_one_worker_using_it
     Process.kill("KILL", pid)
     Process.waitall
     fork do
-      integer_3 = CLASS.new(name: 'TestAtomicInteger', permissions: 0660)
+      integer_3 = CLASS.new(name: 'TestSysVInteger', permissions: 0660)
       assert_equal 109, integer_3.value
     end
     Process.waitall
diff --git a/test/sysv_sliding_window_test.rb b/test/sysv_sliding_window_test.rb
index 888f6d99..3ee7be64 100644
--- a/test/sysv_sliding_window_test.rb
+++ b/test/sysv_sliding_window_test.rb
@@ -1,34 +1,11 @@
 require 'test_helper'
 
 class TestSysVSlidingWindow < MiniTest::Unit::TestCase
-  # Emulate sharedness to test correctness against real SysVSlidingWindow class
-  class FakeSysVSlidingWindow < Semian::Simple::SlidingWindow
-    class << self
-      attr_accessor :resources
-    end
-    self.resources = {}
-    attr_accessor :name
-    def self.new(max_size:, name:, permissions:)
-      obj = resources[name] ||= super
-      obj.name = name
-      obj.resize_to(max_size)
-      obj
-    end
-
-    def destroy
-      self.class.resources.delete(@name)
-    end
-
-    def shared?
-      true
-    end
-  end
-
   CLASS = ::Semian::SysV::SlidingWindow
 
   def setup
     @sliding_window = CLASS.new(max_size: 6,
-                                name: 'TestSlidingWindow',
+                                name: 'TestSysVSlidingWindow',
                                 permissions: 0660)
     @sliding_window.clear
   end
@@ -47,7 +24,7 @@ def test_forcefully_killing_worker_holding_on_to_semaphore_releases_it
 
     pid = fork do
       sliding_window_2 = CLASS.new(max_size: 6,
-                                   name: 'TestSlidingWindow',
+                                   name: 'TestSysVSlidingWindow',
                                    permissions: 0660)
       sliding_window_2.execute_atomically { sleep }
     end
@@ -65,7 +42,7 @@ def test_forcefully_killing_worker_holding_on_to_semaphore_releases_it
   def test_sliding_window_memory_is_actually_shared
     assert_equal 0, @sliding_window.size
     sliding_window_2 = CLASS.new(max_size: 6,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     assert_equal 0, sliding_window_2.size
 
@@ -85,14 +62,14 @@ def test_sliding_window_memory_is_actually_shared
   def test_restarting_worker_should_not_reset_queue
     @sliding_window << 10 << 20 << 30
     sliding_window_2 = CLASS.new(max_size: 6,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     assert_correct_first_and_last_and_size(@sliding_window, 10, 30, 3, 6)
     sliding_window_2.pop
     assert_sliding_windows_in_sync(@sliding_window, sliding_window_2)
 
     sliding_window_3 = CLASS.new(max_size: 6,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     assert_correct_first_and_last_and_size(@sliding_window, 10, 20, 2, 6)
     sliding_window_3.pop
@@ -105,14 +82,14 @@ def test_other_workers_automatically_switching_to_new_memory_resizing_up_or_down
     # Test explicit resizing, and resizing through making new memory associations
 
     sliding_window_2 = CLASS.new(max_size: 4,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     sliding_window_2 << 80 << 90 << 100 << 110 << 120
     assert_correct_first_and_last_and_size(@sliding_window, 90, 120, 4, 4)
     assert_sliding_windows_in_sync(@sliding_window, sliding_window_2)
 
     sliding_window_2 = CLASS.new(max_size: 3,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     assert_sliding_windows_in_sync(@sliding_window, sliding_window_2)
     assert_correct_first_and_last_and_size(@sliding_window, 100, 120, 3, 3)
@@ -122,7 +99,7 @@ def test_other_workers_automatically_switching_to_new_memory_resizing_up_or_down
     assert_correct_first_and_last_and_size(@sliding_window, 110, 120, 2, 2)
 
     sliding_window_2 = CLASS.new(max_size: 4,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     assert_sliding_windows_in_sync(@sliding_window, sliding_window_2)
     assert_correct_first_and_last_and_size(@sliding_window, 110, 120, 2, 4)
@@ -133,7 +110,7 @@ def test_other_workers_automatically_switching_to_new_memory_resizing_up_or_down
     assert_correct_first_and_last_and_size(@sliding_window, 110, 130, 3, 6)
 
     sliding_window_2 = CLASS.new(max_size: 2,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     assert_sliding_windows_in_sync(@sliding_window, sliding_window_2)
     assert_correct_first_and_last_and_size(@sliding_window, 120, 130, 2, 2)
@@ -143,7 +120,7 @@ def test_other_workers_automatically_switching_to_new_memory_resizing_up_or_down
     assert_correct_first_and_last_and_size(@sliding_window, 120, 130, 2, 4)
 
     sliding_window_2 = CLASS.new(max_size: 6,
-                                 name: 'TestSlidingWindow',
+                                 name: 'TestSysVSlidingWindow',
                                  permissions: 0660)
     assert_sliding_windows_in_sync(@sliding_window, sliding_window_2)
     assert_correct_first_and_last_and_size(@sliding_window, 120, 130, 2, 6)
diff --git a/test/sysv_state_test.rb b/test/sysv_state_test.rb
new file mode 100644
index 00000000..a5b77e3b
--- /dev/null
+++ b/test/sysv_state_test.rb
@@ -0,0 +1,44 @@
+require 'test_helper'
+
+class TestSysVState < MiniTest::Unit::TestCase
+  CLASS = ::Semian::SysV::State
+
+  def setup
+    @state = CLASS.new(name: 'TestSysVState',
+                       permissions: 0660)
+  end
+
+  def teardown
+    @state.destroy
+  end
+
+  include TestSimpleState::StateTestCases
+
+  def test_memory_is_shared
+    assert_equal :closed, @state.value
+    @state.open
+
+    state_2 = CLASS.new(name: 'TestSysVState',
+                        permissions: 0660)
+    assert_equal :open, state_2.value
+    assert state_2.open?
+  end
+
+  def test_will_throw_error_when_invalid_symbol_given
+    # May occur if underlying integer gets into bad state
+    integer = @state.instance_eval "@integer"
+    integer.value = 100
+    assert_raises ArgumentError do
+      @state.value
+    end
+    assert_raises ArgumentError do
+      @state.open?
+    end
+    assert_raises ArgumentError do
+      @state.half_open?
+    end
+    assert_raises ArgumentError do
+      @state.closed?
+    end
+  end
+end