diff --git a/lib/vagrant/action/builder.rb b/lib/vagrant/action/builder.rb
index efc8c3e8b..2ed8a968b 100644
--- a/lib/vagrant/action/builder.rb
+++ b/lib/vagrant/action/builder.rb
@@ -23,14 +23,6 @@ module Vagrant
         instance_eval(&block) if block_given?
       end
 
-      # Returns the current stack of middlewares. You probably won't
-      # need to use this directly, and it's recommended that you don't.
-      #
-      # @return [Array]
-      def stack
-        @stack ||= []
-      end
-
       # Returns a mergeable version of the builder. If `use` is called with
       # the return value of this method, then the stack will merge, instead
       # of being treated as a separate single middleware.
@@ -75,9 +67,9 @@ module Vagrant
         insert(index + 1, middleware, *args, &block)
       end
 
-      # Swaps out the given middlware object or index with the new
+      # Replaces the given middlware object or index with the new
       # middleware.
-      def swap(index, middleware, *args, &block)
+      def replace(index, middleware, *args, &block)
         if index.is_a?(Integer)
           delete(index)
           insert(index, middleware, *args, &block)
@@ -93,6 +85,13 @@ module Vagrant
         stack.delete_at(index)
       end
 
+      # Runs the builder stack with the given environment.
+      def call(env)
+        to_app(env).call(env)
+      end
+
+      protected
+
       # Returns the numeric index for the given middleware object.
       #
       # @param [Object] object The item to find the index for
@@ -105,6 +104,14 @@ module Vagrant
         nil
       end
 
+      # Returns the current stack of middlewares. You probably won't
+      # need to use this directly, and it's recommended that you don't.
+      #
+      # @return [Array]
+      def stack
+        @stack ||= []
+      end
+
       # Converts the builder stack to a runnable action sequence.
       #
       # @param [Vagrant::Action::Environment] env The action environment
@@ -114,11 +121,6 @@ module Vagrant
         # and predictable behavior upon exceptions.
         Warden.new(stack.dup, env)
       end
-
-      # Runs the builder stack with the given environment.
-      def call(env)
-        to_app(env).call(env)
-      end
     end
   end
 end
diff --git a/lib/vagrant/action/environment.rb b/lib/vagrant/action/environment.rb
index 769a16832..011601975 100644
--- a/lib/vagrant/action/environment.rb
+++ b/lib/vagrant/action/environment.rb
@@ -7,25 +7,6 @@ module Vagrant
     # some helper methods for accessing the environment as well
     # as being a hash, to store any additional options.
     class Environment < Util::HashWithIndifferentAccess
-      def initialize
-        @interrupted = false
-      end
-
-      # Marks an environment as interrupted (by an outside signal or
-      # anything). This will trigger any middleware sequences using this
-      # environment to halt. This is automatically set by {Action} when
-      # a SIGINT is captured.
-      def interrupt!
-        @interrupted = true
-      end
-
-      # Returns a boolean denoting if environment has been interrupted
-      # with a SIGINT.
-      #
-      # @return [Bool]
-      def interrupted?
-        !!@interrupted
-      end
     end
   end
 end
diff --git a/lib/vagrant/action/runner.rb b/lib/vagrant/action/runner.rb
index aa667e009..57deccfc6 100644
--- a/lib/vagrant/action/runner.rb
+++ b/lib/vagrant/action/runner.rb
@@ -34,13 +34,13 @@ module Vagrant
         # chain has been run.
         ui = environment[:ui] if environment.has_key?(:ui)
         int_callback = lambda do
-          if environment.interrupted?
+          if environment[:interrupted]
             ui.error I18n.t("vagrant.actions.runner.exit_immediately") if ui
             abort
           end
 
           ui.warn I18n.t("vagrant.actions.runner.waiting_cleanup") if ui && !@@reported_interrupt
-          environment.interrupt!
+          environment[:interrupted] = true
           @@reported_interrupt = true
         end
 
diff --git a/lib/vagrant/action/warden.rb b/lib/vagrant/action/warden.rb
index 42c50e49a..8a5d4978d 100644
--- a/lib/vagrant/action/warden.rb
+++ b/lib/vagrant/action/warden.rb
@@ -27,11 +27,11 @@ module Vagrant
         begin
           # Call the next middleware in the sequence, appending to the stack
           # of "recoverable" middlewares in case something goes wrong!
-          raise Errors::VagrantInterrupt if env.interrupted?
+          raise Errors::VagrantInterrupt if env[:interrupted]
           action = @actions.shift
           @logger.info("Calling action: #{action}")
           @stack.unshift(action).first.call(env)
-          raise Errors::VagrantInterrupt if env.interrupted?
+          raise Errors::VagrantInterrupt if env[:interrupted]
         rescue SystemExit
           # This means that an "exit" or "abort" was called. In these cases,
           # we just exit immediately.
diff --git a/test/unit/vagrant/action/builder_test.rb b/test/unit/vagrant/action/builder_test.rb
new file mode 100644
index 000000000..3eb09f304
--- /dev/null
+++ b/test/unit/vagrant/action/builder_test.rb
@@ -0,0 +1,161 @@
+require File.expand_path("../../../base", __FILE__)
+
+describe Vagrant::Action::Builder do
+  let(:data) { { :data => [] } }
+  let(:instance) { described_class.new }
+
+  # This returns a proc that can be used with the builder
+  # that simply appends data to an array in the env.
+  def appender_proc(data)
+    Proc.new { |env| env[:data] << data }
+  end
+
+  context "basic `use`" do
+    it "should add items to the stack and make them callable" do
+      data = {}
+      proc = Proc.new { |env| env[:data] = true }
+
+      instance.use proc
+      instance.call(data)
+
+      data[:data].should == true
+    end
+
+    it "should be able to add multiple items" do
+      data = {}
+      proc1 = Proc.new { |env| env[:one] = true }
+      proc2 = Proc.new { |env| env[:two] = true }
+
+      instance.use proc1
+      instance.use proc2
+      instance.call(data)
+
+      data[:one].should == true
+      data[:two].should == true
+    end
+
+    it "should be able to add another builder" do
+      data  = {}
+      proc1 = Proc.new { |env| env[:one] = true }
+
+      # Build the first builder
+      one   = described_class.new
+      one.use proc1
+
+      # Add it to this builder
+      two   = described_class.new
+      two.use one
+
+      # Call the 2nd and verify results
+      two.call(data)
+      data[:one].should == true
+    end
+
+    it "should be able to set additional variables if using another builder" do
+      data  = { }
+      proc1 = Proc.new { |env| env[:data] += 1 }
+
+      # Build the first builder
+      one   = described_class.new
+      one.use proc1
+
+      # Add it to this builder
+      two   = described_class.new
+      two.use one, :data => 10
+
+      # Call the 2nd and verify results
+      two.call(data)
+      data[:data].should == 11
+    end
+  end
+
+  context "inserting" do
+    it "can insert at an index" do
+      instance.use appender_proc(1)
+      instance.insert(0, appender_proc(2))
+      instance.call(data)
+
+      data[:data].should == [2, 1]
+    end
+
+    it "can insert next to a previous object" do
+      proc2 = appender_proc(2)
+      instance.use appender_proc(1)
+      instance.use proc2
+      instance.insert(proc2, appender_proc(3))
+      instance.call(data)
+
+      data[:data].should == [1, 3, 2]
+    end
+
+    it "can insert before" do
+      instance.use appender_proc(1)
+      instance.insert_before 0, appender_proc(2)
+      instance.call(data)
+
+      data[:data].should == [2, 1]
+    end
+
+    it "can insert after" do
+      instance.use appender_proc(1)
+      instance.use appender_proc(3)
+      instance.insert_after 0, appender_proc(2)
+      instance.call(data)
+
+      data[:data].should == [1, 2, 3]
+    end
+
+    it "raises an exception if an invalid object given" do
+      expect { instance.insert_after "object", appender_proc(1) }.
+        to raise_error(RuntimeError)
+    end
+  end
+
+  context "replace" do
+    it "can replace an object" do
+      proc1 = appender_proc(1)
+      proc2 = appender_proc(2)
+
+      instance.use proc1
+      instance.replace proc1, proc2
+      instance.call(data)
+
+      data[:data].should == [2]
+    end
+
+    it "can replace by index" do
+      proc1 = appender_proc(1)
+      proc2 = appender_proc(2)
+
+      instance.use proc1
+      instance.replace 0, proc2
+      instance.call(data)
+
+      data[:data].should == [2]
+    end
+  end
+
+  context "deleting" do
+    it "can delete by object" do
+      proc1 = appender_proc(1)
+
+      instance.use proc1
+      instance.use appender_proc(2)
+      instance.delete proc1
+      instance.call(data)
+
+      data[:data].should == [2]
+    end
+
+    it "can delete by index" do
+      proc1 = appender_proc(1)
+
+      instance.use proc1
+      instance.use appender_proc(2)
+      instance.delete 0
+      instance.call(data)
+
+      data[:data].should == [2]
+    end
+  end
+end
diff --git a/test/unit/vagrant/action/environment_test.rb b/test/unit/vagrant/action/environment_test.rb
index 4f278d566..e516429bc 100644
--- a/test/unit/vagrant/action/environment_test.rb
+++ b/test/unit/vagrant/action/environment_test.rb
@@ -13,10 +13,4 @@ describe Vagrant::Action::Environment do
     instance["foo"] = "bar"
     instance[:foo].should == "bar"
   end
-
-  it "should keep track of interrupted state" do
-    instance.should_not be_interrupted
-    instance.interrupt!
-    instance.should be_interrupted
-  end
 end
diff --git a/test/unit_legacy/vagrant/action/builder_test.rb b/test/unit_legacy/vagrant/action/builder_test.rb
deleted file mode 100644
index cc0e350e2..000000000
--- a/test/unit_legacy/vagrant/action/builder_test.rb
+++ /dev/null
@@ -1,207 +0,0 @@
-require "test_helper"
-require "logger"
-
-class ActionBuilderTest < Test::Unit::TestCase
-  setup do
-    @klass = Vagrant::Action::Builder
-  end
-
-  context "initializing" do
-    should "setup empty middleware stack" do
-      builder = @klass.new
-      assert builder.stack.empty?
-    end
-
-    should "take block to setup stack" do
-      builder = @klass.new do
-        use Hash
-        use lambda { |i| i }
-      end
-
-      assert !builder.stack.empty?
-      assert_equal 2, builder.stack.length
-    end
-  end
-
-  context "with an instance" do
-    setup do
-      @instance = @klass.new
-    end
-
-    context "adding to the stack" do
-      should "return self" do
-        assert @instance.equal?(@instance.use(1))
-      end
-
-      should "add to the end" do
-        @instance.use 1
-        @instance.use 2
-        assert_equal [2, [], nil], @instance.stack.last
-      end
-
-      should "merge in other builder's stack" do
-        other = @klass.new do
-          use 2
-          use 3
-        end
-
-        @instance.use 1
-        @instance.use other
-        assert_equal 3, @instance.stack.length
-      end
-
-      should "prepend a set environment task for merging middlewares if given" do
-        other = @klass.new do
-          use 1
-        end
-
-        @instance.use 0
-        @instance.use(other, :foo => :bar)
-        assert_equal 3, @instance.stack.length
-        assert_equal Vagrant::Action::Env::Set, @instance.stack[1].first
-      end
-    end
-
-    context "flatten" do
-      should "return the flattened format of the builder" do
-        env = Vagrant::Action::Environment.new(nil)
-        env["logger"] = Logger.new(nil)
-        env.expects(:foo).once
-
-        func = lambda { |x| x.foo }
-        @instance.use func
-        proc = @instance.flatten
-        assert proc.respond_to?(:call)
-        proc.call(env)
-      end
-    end
-
-    context "inserting" do
-      setup do
-        @instance.use "1"
-        @instance.use "2"
-      end
-
-      should "insert at the proper numeric index" do
-        @instance.insert(1, "3")
-        assert_equal "3", @instance.stack[1].first
-      end
-
-      should "insert next to the proper object if given" do
-        @instance.insert("2", "3")
-        assert_equal "3", @instance.stack[1].first
-      end
-
-      should "be able to call insert_before as well" do
-        @instance.insert_before("1", "0")
-        assert_equal "0", @instance.stack.first.first
-      end
-
-      should "be able to insert_after" do
-        @instance.insert_after("1", "0")
-        assert_equal "0", @instance.stack[1].first
-      end
-
-      should "be able to insert_after using numeric index" do
-        @instance.insert_after(1, "0")
-        assert_equal "0", @instance.stack[2].first
-      end
-
-      should "raise an exception if invalid index" do
-        assert_raises(RuntimeError) {
-          @instance.insert_after("15", "0")
-        }
-      end
-    end
-
-    context "swapping" do
-      setup do
-        @instance.use "1"
-        @instance.use "2"
-      end
-
-      should "be able to swap using the object" do
-        @instance.swap "1", "3"
-        assert_equal "3", @instance.stack.first.first
-      end
-
-      should "be able to swap using the index" do
-        @instance.swap 0, "3"
-        assert_equal "3", @instance.stack.first.first
-      end
-    end
-
-    context "deleting" do
-      setup do
-        @instance.use "1"
-      end
-
-      should "delete the proper object" do
-        @instance.delete("1")
-        assert @instance.stack.empty?
-      end
-
-      should "delete by index if given" do
-        @instance.delete(0)
-        assert @instance.stack.empty?
-      end
-    end
-
-    context "getting an index of an object" do
-      should "return the proper index if it exists" do
-        @instance.use 1
-        @instance.use 2
-        @instance.use 3
-        assert_equal 1, @instance.index(2)
-      end
-    end
-
-    context "converting to an app" do
-      should "make non-classes lambdas" do
-        env = Vagrant::Action::Environment.new(nil)
-        env["logger"] = Logger.new(nil)
-        env.expects(:foo).once
-
-        func = lambda { |x| x.foo }
-        @instance.use func
-        @instance.to_app(env).call(env)
-      end
-
-      should "raise exception if given invalid middleware" do
-        @instance.use 7
-        assert_raises(RuntimeError) {
-          @instance.to_app(nil)
-        }
-      end
-    end
-
-    context "calling" do
-      def mock_middleware
-        middleware = Class.new do
-          def initialize(app, env)
-            @app = app
-          end
-
-          def call(env)
-            @app.call(env)
-          end
-        end
-      end
-
-      should "convert to an app then call with the env" do
-        mw = mock_middleware
-        mw.any_instance.expects(:call).with() do |env|
-          assert env.has_key?(:key)
-          true
-        end
-
-        env = Vagrant::Action::Environment.new(nil)
-        env["logger"] = Logger.new(nil)
-        env[:key] = :value
-
-        @instance.use(mw)
-        @instance.call(env)
-      end
-    end
-  end
-end