From 52f3847b0af83f42cfb9eb3f0ba0c510c0923c06 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 3 Apr 2013 21:47:57 -0700
Subject: [PATCH] Laying the foundation for the new guest plugin

---
 lib/vagrant/errors.rb               |   4 ++
 lib/vagrant/guest.rb                | 101 ++++++++++++++++++++++++++++
 lib/vagrant/machine.rb              |  28 +-------
 lib/vagrant/plugin/v2/components.rb |   6 ++
 lib/vagrant/plugin/v2/guest.rb      |  40 ++++-------
 lib/vagrant/plugin/v2/manager.rb    |   2 +-
 lib/vagrant/plugin/v2/plugin.rb     |  15 ++---
 plugins/guests/arch/guest.rb        |   4 ++
 plugins/guests/arch/plugin.rb       |   2 +-
 plugins/guests/debian/guest.rb      |   4 ++
 plugins/guests/debian/plugin.rb     |   2 +-
 plugins/guests/fedora/guest.rb      |   4 ++
 plugins/guests/fedora/plugin.rb     |   2 +-
 plugins/guests/freebsd/guest.rb     |   5 ++
 plugins/guests/gentoo/guest.rb      |   4 ++
 plugins/guests/gentoo/plugin.rb     |   2 +-
 plugins/guests/linux/guest.rb       |   5 ++
 plugins/guests/openbsd/guest.rb     |   5 ++
 plugins/guests/openbsd/plugin.rb    |   2 +-
 plugins/guests/pld/guest.rb         |   4 ++
 plugins/guests/pld/plugin.rb        |   2 +-
 plugins/guests/redhat/guest.rb      |   4 ++
 plugins/guests/redhat/plugin.rb     |   2 +-
 plugins/guests/solaris/guest.rb     |   4 ++
 plugins/guests/suse/guest.rb        |   4 ++
 plugins/guests/suse/plugin.rb       |   2 +-
 plugins/guests/ubuntu/guest.rb      |   4 ++
 plugins/guests/ubuntu/plugin.rb     |   2 +-
 templates/locales/en.yml            |  18 ++---
 test/unit/vagrant/guest_test.rb     |  75 +++++++++++++++++++++
 test/unit/vagrant/machine_test.rb   |  55 ++-------------
 31 files changed, 281 insertions(+), 132 deletions(-)
 create mode 100644 lib/vagrant/guest.rb
 create mode 100644 test/unit/vagrant/guest_test.rb

diff --git a/lib/vagrant/errors.rb b/lib/vagrant/errors.rb
index 084d66c84..9db88ceb6 100644
--- a/lib/vagrant/errors.rb
+++ b/lib/vagrant/errors.rb
@@ -227,6 +227,10 @@ module Vagrant
       error_key(:port_collision_resume)
     end
 
+    class GuestNotDetected < VagrantError
+      error_key(:guest_not_detected)
+    end
+
     class LocalDataDirectoryNotAccessible < VagrantError
       error_key(:local_data_dir_not_accessible)
     end
diff --git a/lib/vagrant/guest.rb b/lib/vagrant/guest.rb
new file mode 100644
index 000000000..52dcd3e21
--- /dev/null
+++ b/lib/vagrant/guest.rb
@@ -0,0 +1,101 @@
+require "log4r"
+
+module Vagrant
+  # This class handles guest-OS specific interactions with a machine.
+  # It is primarily responsible for detecting the proper guest OS
+  # implementation and then delegating capabilities.
+  #
+  # Vagrant has many tasks which require specific guest OS knowledge.
+  # These are implemented using a guest/capability system. Various plugins
+  # register as "guests" which determine the underlying OS of the system.
+  # Then, "guest capabilities" register themselves for a specific OS (one
+  # or more), and these capabilities are called.
+  #
+  # Example capabilities might be "mount_virtualbox_shared_folder" or
+  # "configure_networks".
+  #
+  # This system allows for maximum flexibility and pluginability for doing
+  # guest OS specific operations.
+  class Guest
+    attr_reader :chain
+
+    def initialize(machine, guests)
+      @logger  = Log4r::Logger.new("vagrant::guest")
+      @chain   = []
+      @guests  = guests
+      @machine = machine
+    end
+
+    # This will detect the proper guest OS for the machine and set up
+    # the class to actually execute capabilities.
+    def detect!
+      @logger.info("Detect guest for machine: #{@machine}")
+
+      # Get the mapping of guests with the most parents. We start searching
+      # with the guests with the most parents first.
+      parent_count = {}
+      @guests.each do |name, parts|
+        parent_count[name] = 0
+
+        parent = parts[1]
+        while parent
+          parent_count[name] += 1
+          parent = @guests[parent]
+          parent = parent[1] if parent
+        end
+      end
+
+      # Now swap around the mapping so that it is a mapping of
+      # count to the actual list of guest names
+      parent_count_to_guests = {}
+      parent_count.each do |name, count|
+        parent_count_to_guests[count] ||= []
+        parent_count_to_guests[count] << name
+      end
+
+      catch(:guest_os) do
+        sorted_counts = parent_count_to_guests.keys.sort.reverse
+        sorted_counts.each do |count|
+          parent_count_to_guests[count].each do |name|
+            @logger.debug("Trying: #{name}")
+            guest_info = @guests[name]
+            guest      = guest_info[0].new
+
+            if guest.detect?(@machine)
+              @logger.info("Detected: #{name}!")
+              @chain << guest
+
+              # Build the proper chain of parents if there are any.
+              # This allows us to do "inheritence" of capabilities later
+              if guest_info[1]
+                parent_info = @guests[guest_info[1]]
+                while parent_info
+                  @chain << parent_info[0].new
+                  parent_info = @guests[parent_info[1]]
+                end
+              end
+
+              @logger.info("Full guest chain: #{@chain.inspect}")
+
+              # Exit the search
+              throw :guest_os
+            end
+          end
+        end
+      end
+
+      # We shouldn't reach this point. Ideally we would detect
+      # all operating systems.
+      raise Errors::GuestNotDetected if @chain.empty?
+    end
+
+    # This returns whether the guest is ready to work. If this returns
+    # `false`, then {#detect!} should be called in order to detect the
+    # guest OS.
+    #
+    # @return [Boolean]
+    def ready?
+      !@chain.empty?
+    end
+  end
+end
diff --git a/lib/vagrant/machine.rb b/lib/vagrant/machine.rb
index f8be78aef..0b12580b1 100644
--- a/lib/vagrant/machine.rb
+++ b/lib/vagrant/machine.rb
@@ -83,6 +83,7 @@ module Vagrant
       @config          = config
       @data_dir        = data_dir
       @env             = env
+      @guest           = Guest.new(self)
       @name            = name
       @provider_config = provider_config
       @provider_name   = provider_name
@@ -169,32 +170,7 @@ module Vagrant
     # @return [Object]
     def guest
       raise Errors::MachineGuestNotReady if !communicate.ready?
-
-      # Load the initial guest.
-      last_guest = config.vm.guest
-      guest      = load_guest(last_guest)
-
-      # Loop and distro dispatch while there are distros.
-      while true
-        distro = guest.distro_dispatch
-        break if !distro
-
-        # This is just some really basic loop detection and avoiding for
-        # guest classes. This is just here to help implementers a bit
-        # avoid a situation that is fairly easy, since if you subclass
-        # a parent which does `distro_dispatch`, you'll end up dispatching
-        # forever.
-        if distro == last_guest
-          @logger.warn("Distro dispatch loop in '#{distro}'. Exiting loop.")
-          break
-        end
-
-        last_guest = distro
-        guest      = load_guest(distro)
-      end
-
-      # Return the result
-      guest
+      @guest
     end
 
     # This sets the unique ID associated with this machine. This will
diff --git a/lib/vagrant/plugin/v2/components.rb b/lib/vagrant/plugin/v2/components.rb
index 9510b0a87..636f7ae6c 100644
--- a/lib/vagrant/plugin/v2/components.rb
+++ b/lib/vagrant/plugin/v2/components.rb
@@ -16,6 +16,11 @@ module Vagrant
         # @return [Hash<Symbol, Registry>]
         attr_reader :configs
 
+        # This contains all the guests and their parents.
+        #
+        # @return [Registry<Symbol, Array<Class, Symbol>>]
+        attr_reader :guests
+
         # This contains all the provider plugins by name, and returns
         # the provider class and options.
         #
@@ -27,6 +32,7 @@ module Vagrant
           @action_hooks = Hash.new { |h, k| h[k] = [] }
 
           @configs = Hash.new { |h, k| h[k] = Registry.new }
+          @guests  = Registry.new
           @providers = Registry.new
         end
       end
diff --git a/lib/vagrant/plugin/v2/guest.rb b/lib/vagrant/plugin/v2/guest.rb
index f757296dd..9af83887b 100644
--- a/lib/vagrant/plugin/v2/guest.rb
+++ b/lib/vagrant/plugin/v2/guest.rb
@@ -1,35 +1,21 @@
 module Vagrant
   module Plugin
     module V2
-      # The base class for a guest. A guest represents an installed system
-      # within a machine that Vagrant manages. There are some portions of
-      # Vagrant which are OS-specific such as mountaing shared folders and
-      # halting the machine, and this abstraction allows the implementation
-      # for these to be seperate from the core of Vagrant.
+      # A base class for a guest OS. A guest OS is responsible for detecting
+      # that the guest operating system running within the machine. The guest
+      # can then be extended with various "guest capabilities" which are their
+      # own form of plugin.
+      #
+      # The guest class itself is only responsible for detecting itself,
+      # and may provide helpers for the capabilties.
       class Guest
-        class BaseError < Errors::VagrantError
-          error_namespace("vagrant.guest.base")
-        end
-
-        include Vagrant::Util
-
-        # The VM which this system is tied to.
-        attr_reader :vm
-
-        # Initializes the system. Any subclasses MUST make sure this
-        # method is called on the parent. Therefore, if a subclass overrides
-        # `initialize`, then you must call `super`.
-        def initialize(vm)
-          @vm = vm
-        end
-
-        # This method is automatically called when the system is available (when
-        # Vagrant can successfully SSH into the machine) to give the system a chance
-        # to determine the distro and return a distro-specific system.
+        # This method is called when the machine is booted and has communication
+        # capabilities in order to detect whether this guest operating system
+        # is running within the machine.
         #
-        # If this method returns nil, then this instance is assumed to be
-        # the most specific guest implementation.
-        def distro_dispatch
+        # @return [Boolean]
+        def guest?(machine)
+          false
         end
 
         # Halt the machine. This method should gracefully shut down the
diff --git a/lib/vagrant/plugin/v2/manager.rb b/lib/vagrant/plugin/v2/manager.rb
index f7cfa5c4e..887bd5c0e 100644
--- a/lib/vagrant/plugin/v2/manager.rb
+++ b/lib/vagrant/plugin/v2/manager.rb
@@ -67,7 +67,7 @@ module Vagrant
         def guests
           Registry.new.tap do |result|
             @registered.each do |plugin|
-              result.merge!(plugin.guest)
+              result.merge!(plugin.components.guests)
             end
           end
         end
diff --git a/lib/vagrant/plugin/v2/plugin.rb b/lib/vagrant/plugin/v2/plugin.rb
index be2d11802..0480631fc 100644
--- a/lib/vagrant/plugin/v2/plugin.rb
+++ b/lib/vagrant/plugin/v2/plugin.rb
@@ -124,7 +124,6 @@ module Vagrant
         # without breaking anything in future versions of Vagrant.
         #
         # @param [String] name Configuration key.
-        # XXX: Document options hash
         def self.config(name, scope=nil, &block)
           scope ||= :top
           components.configs[scope].register(name.to_sym, &block)
@@ -135,14 +134,14 @@ module Vagrant
         # the given key.
         #
         # @param [String] name Name of the guest.
-        def self.guest(name=UNSET_VALUE, &block)
-          data[:guests] ||= Registry.new
+        # @param [String] parent Name of the parent guest (if any)
+        def self.guest(name=UNSET_VALUE, parent=nil, &block)
+          components.guests.register(name.to_sym) do
+            parent = parent.to_sym if parent
 
-          # Register a new guest class only if a name was given
-          data[:guests].register(name.to_sym, &block) if name != UNSET_VALUE
-
-          # Return the registry
-          data[:guests]
+            [block.call, parent]
+          end
+          nil
         end
 
         # Defines an additionally available host implementation with
diff --git a/plugins/guests/arch/guest.rb b/plugins/guests/arch/guest.rb
index 7b0b5f373..a354f6799 100644
--- a/plugins/guests/arch/guest.rb
+++ b/plugins/guests/arch/guest.rb
@@ -12,6 +12,10 @@ module VagrantPlugins
       # Make the TemplateRenderer top-level
       include Vagrant::Util
 
+      def detect?(machine)
+        machine.communicate.test("cat /etc/arch-release")
+      end
+
       def change_host_name(name)
         # Only do this if the hostname is not already set
         if !vm.communicate.test("sudo hostname | grep '#{name}'")
diff --git a/plugins/guests/arch/plugin.rb b/plugins/guests/arch/plugin.rb
index bcbb945ae..36c2d76ce 100644
--- a/plugins/guests/arch/plugin.rb
+++ b/plugins/guests/arch/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "Arch guest"
       description "Arch guest support."
 
-      guest("arch") do
+      guest("arch", "linux") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/debian/guest.rb b/plugins/guests/debian/guest.rb
index c5a32cb19..2712b32c7 100644
--- a/plugins/guests/debian/guest.rb
+++ b/plugins/guests/debian/guest.rb
@@ -12,6 +12,10 @@ module VagrantPlugins
       # Make the TemplateRenderer top-level
       include Vagrant::Util
 
+      def detect?(machine)
+        machine.communicate.test("cat /proc/version | grep 'Debian'")
+      end
+
       def configure_networks(networks)
         # First, remove any previous network modifications
         # from the interface file.
diff --git a/plugins/guests/debian/plugin.rb b/plugins/guests/debian/plugin.rb
index 7cb276635..b9190d4bf 100644
--- a/plugins/guests/debian/plugin.rb
+++ b/plugins/guests/debian/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "Debian guest"
       description "Debian guest support."
 
-      guest("debian") do
+      guest("debian", "linux") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/fedora/guest.rb b/plugins/guests/fedora/guest.rb
index 54856a3f5..f32d8f3d2 100644
--- a/plugins/guests/fedora/guest.rb
+++ b/plugins/guests/fedora/guest.rb
@@ -12,6 +12,10 @@ module VagrantPlugins
       # Make the TemplateRenderer top-level
       include Vagrant::Util
 
+      def detect?(machine)
+        machine.communicate.test("grep 'Fedora release 1[678]' /etc/redhat-release")
+      end
+
       def configure_networks(networks)
         # Accumulate the configurations to add to the interfaces file as well
         # as what interfaces we're actually configuring since we use that later.
diff --git a/plugins/guests/fedora/plugin.rb b/plugins/guests/fedora/plugin.rb
index 29323f188..73bbcb911 100644
--- a/plugins/guests/fedora/plugin.rb
+++ b/plugins/guests/fedora/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "Fedora guest"
       description "Fedora guest support."
 
-      guest("fedora") do
+      guest("fedora", "linux") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/freebsd/guest.rb b/plugins/guests/freebsd/guest.rb
index 7a3b5ea66..c5ff14951 100644
--- a/plugins/guests/freebsd/guest.rb
+++ b/plugins/guests/freebsd/guest.rb
@@ -11,6 +11,11 @@ module VagrantPlugins
         error_namespace("vagrant.guest.freebsd")
       end
 
+      def detect?(machine)
+        # TODO: FreeBSD detection
+        false
+      end
+
       def halt
         begin
           vm.communicate.sudo("shutdown -p now")
diff --git a/plugins/guests/gentoo/guest.rb b/plugins/guests/gentoo/guest.rb
index 2f59dbd2c..5aaacd573 100644
--- a/plugins/guests/gentoo/guest.rb
+++ b/plugins/guests/gentoo/guest.rb
@@ -11,6 +11,10 @@ module VagrantPlugins
       # Make the TemplateRenderer top-level
       include Vagrant::Util
 
+      def detect?(machine)
+        machine.communicate.test("cat /etc/gentoo-release")
+      end
+
       def configure_networks(networks)
         # Remove any previous host only network additions to the interface file
         vm.communicate.sudo("sed -e '/^#VAGRANT-BEGIN/,/^#VAGRANT-END/ d' /etc/conf.d/net > /tmp/vagrant-network-interfaces")
diff --git a/plugins/guests/gentoo/plugin.rb b/plugins/guests/gentoo/plugin.rb
index c888d811d..b37b39565 100644
--- a/plugins/guests/gentoo/plugin.rb
+++ b/plugins/guests/gentoo/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "Gentoo guest"
       description "Gentoo guest support."
 
-      guest("gentoo") do
+      guest("gentoo", "linux") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/linux/guest.rb b/plugins/guests/linux/guest.rb
index 7c649be92..f0bc77c1d 100644
--- a/plugins/guests/linux/guest.rb
+++ b/plugins/guests/linux/guest.rb
@@ -18,6 +18,11 @@ module VagrantPlugins
         @logger = Log4r::Logger.new("vagrant::guest::linux")
       end
 
+      def detect?(machine)
+        # TODO: Linux detection
+        false
+      end
+
       def distro_dispatch
         @vm.communicate.tap do |comm|
           if comm.test("cat /etc/debian_version")
diff --git a/plugins/guests/openbsd/guest.rb b/plugins/guests/openbsd/guest.rb
index dd4a4831a..8a4e6408d 100644
--- a/plugins/guests/openbsd/guest.rb
+++ b/plugins/guests/openbsd/guest.rb
@@ -5,6 +5,11 @@ require Vagrant.source_root.join("plugins/guests/linux/guest")
 module VagrantPlugins
   module GuestOpenBSD
     class Guest < VagrantPlugins::GuestLinux::Guest
+      def detect?(machine)
+        # TODO: OpenBSD detection
+        false
+      end
+
       def halt
         vm.communicate.sudo("shutdown -p -h now")
       end
diff --git a/plugins/guests/openbsd/plugin.rb b/plugins/guests/openbsd/plugin.rb
index ce74391c0..dd6f38a76 100644
--- a/plugins/guests/openbsd/plugin.rb
+++ b/plugins/guests/openbsd/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "OpenBSD guest"
       description "OpenBSD guest support."
 
-      guest("openbsd") do
+      guest("openbsd", "linux") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/pld/guest.rb b/plugins/guests/pld/guest.rb
index b183102a4..a2d7ad881 100644
--- a/plugins/guests/pld/guest.rb
+++ b/plugins/guests/pld/guest.rb
@@ -5,6 +5,10 @@ require Vagrant.source_root.join("plugins/guests/redhat/guest")
 module VagrantPlugins
   module GuestPld
     class Guest < VagrantPlugins::GuestRedHat::Guest
+      def detect?(machine)
+        machine.communicate.test("cat /etc/pld-release")
+      end
+
       def network_scripts_dir
         '/etc/sysconfig/interfaces/'
       end
diff --git a/plugins/guests/pld/plugin.rb b/plugins/guests/pld/plugin.rb
index b072ed9f6..bd457b8c1 100644
--- a/plugins/guests/pld/plugin.rb
+++ b/plugins/guests/pld/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "PLD Linux guest"
       description "PLD Linux guest support."
 
-      guest("pld") do
+      guest("pld", "redhat") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/redhat/guest.rb b/plugins/guests/redhat/guest.rb
index 39c508856..0ac990ea0 100644
--- a/plugins/guests/redhat/guest.rb
+++ b/plugins/guests/redhat/guest.rb
@@ -12,6 +12,10 @@ module VagrantPlugins
       # Make the TemplateRenderer top-level
       include Vagrant::Util
 
+      def detect?(machine)
+        machine.communicate.test("cat /etc/redhat-release")
+      end
+
       def configure_networks(networks)
         # Accumulate the configurations to add to the interfaces file as
         # well as what interfaces we're actually configuring since we use that
diff --git a/plugins/guests/redhat/plugin.rb b/plugins/guests/redhat/plugin.rb
index 4355152ff..dd80ef78f 100644
--- a/plugins/guests/redhat/plugin.rb
+++ b/plugins/guests/redhat/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "RedHat guest"
       description "RedHat guest support."
 
-      guest("redhat") do
+      guest("redhat", "linux") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/solaris/guest.rb b/plugins/guests/solaris/guest.rb
index a5f13c92e..a815748d0 100644
--- a/plugins/guests/solaris/guest.rb
+++ b/plugins/guests/solaris/guest.rb
@@ -11,6 +11,10 @@ module VagrantPlugins
         error_namespace("vagrant.guest.solaris")
       end
 
+      def detect?(machine)
+        machine.communicate.test("grep 'Solaris' /etc/release")
+      end
+
       def configure_networks(networks)
         networks.each do |network|
           device = "#{vm.config.solaris.device}#{network[:interface]}"
diff --git a/plugins/guests/suse/guest.rb b/plugins/guests/suse/guest.rb
index 8694b669e..e6caeda45 100644
--- a/plugins/guests/suse/guest.rb
+++ b/plugins/guests/suse/guest.rb
@@ -5,6 +5,10 @@ require Vagrant.source_root.join("plugins/guests/redhat/guest")
 module VagrantPlugins
   module GuestSuse
     class Guest < VagrantPlugins::GuestRedHat::Guest
+      def detect?(machine)
+        machine.communicate.test("cat /etc/SuSE-release")
+      end
+
       def network_scripts_dir
         '/etc/sysconfig/network/'
       end
diff --git a/plugins/guests/suse/plugin.rb b/plugins/guests/suse/plugin.rb
index 12e925f02..0fd401ea7 100644
--- a/plugins/guests/suse/plugin.rb
+++ b/plugins/guests/suse/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "SUSE guest"
       description "SUSE guest support."
 
-      guest("suse") do
+      guest("suse", "redhat") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/plugins/guests/ubuntu/guest.rb b/plugins/guests/ubuntu/guest.rb
index bc199b535..707f2e8fa 100644
--- a/plugins/guests/ubuntu/guest.rb
+++ b/plugins/guests/ubuntu/guest.rb
@@ -5,6 +5,10 @@ require Vagrant.source_root.join("plugins/guests/debian/guest")
 module VagrantPlugins
   module GuestUbuntu
     class Guest < VagrantPlugins::GuestDebian::Guest
+      def detect?(machine)
+        machine.communicate.test("cat /proc/version | grep 'Ubuntu'")
+      end
+
       def mount_shared_folder(name, guestpath, options)
         # Mount it like normal
         super
diff --git a/plugins/guests/ubuntu/plugin.rb b/plugins/guests/ubuntu/plugin.rb
index 8e3cc72c1..f8e5c0708 100644
--- a/plugins/guests/ubuntu/plugin.rb
+++ b/plugins/guests/ubuntu/plugin.rb
@@ -6,7 +6,7 @@ module VagrantPlugins
       name "Ubuntu guest"
       description "Ubuntu guest support."
 
-      guest("ubuntu") do
+      guest("ubuntu", "debian") do
         require File.expand_path("../guest", __FILE__)
         Guest
       end
diff --git a/templates/locales/en.yml b/templates/locales/en.yml
index 832fb2701..ea5ae4d1d 100644
--- a/templates/locales/en.yml
+++ b/templates/locales/en.yml
@@ -173,18 +173,12 @@ en:
         of the official installers or another gem is wrongly attempting to
         use Vagrant internals directly. Please properly install Vagrant to
         fix this. If this error persists, please contact support.
-      guest:
-        invalid_class: |-
-          The specified guest class does not inherit from a proper guest
-          component class. The guest class must inherit from this.
-
-          The specified guest class was: %{guest}
-        unknown_type: |-
-          The specified guest type is unknown: %{guest}. Please change this
-          to a proper value.
-        unspecified: |-
-          A VM guest type must be specified! This is done via the `config.vm.guest`
-          configuration value. Please read the documentation online for more information.
+      guest_not_detected: |-
+        The guest operating system of the machine could not be detected!
+        Vagrant requires this knowledge to perform specific tasks such
+        as mounting shared folders and configuring networks. Please add
+        the ability to detect this guest operating system to Vagrant
+        by creating a plugin or reporting a bug.
       home_dir_not_accessible: |-
         The home directory you specified is not accessible. The home
         directory that Vagrant uses must be both readable and writable.
diff --git a/test/unit/vagrant/guest_test.rb b/test/unit/vagrant/guest_test.rb
new file mode 100644
index 000000000..0cff98738
--- /dev/null
+++ b/test/unit/vagrant/guest_test.rb
@@ -0,0 +1,75 @@
+require "pathname"
+
+require File.expand_path("../../base", __FILE__)
+
+describe Vagrant::Guest do
+  include_context "unit"
+
+  let(:guests)  { {} }
+  let(:machine) { double("machine") }
+
+  subject { described_class.new(machine, guests) }
+
+  # This registers a guest with the class.
+  #
+  # @param [Symbol] name Name of the guest
+  # @param [Symbol] parent Name of the parent
+  # @param [Boolean] detect Whether or not to detect properly
+  def register_guest(name, parent, detect)
+    guest = Class.new(Vagrant.plugin("2", "guest")) do
+      define_method(:name) do
+        name
+      end
+
+      define_method(:detect?) do |m|
+        detect
+      end
+    end
+
+    guests[name] = [guest, parent]
+  end
+
+  describe "#detect!" do
+    it "detects the first match" do
+      register_guest(:foo, nil, false)
+      register_guest(:bar, nil, true)
+      register_guest(:baz, nil, false)
+
+      subject.detect!
+      subject.chain.length.should == 1
+      subject.chain[0].name.should == :bar
+    end
+
+    it "detects those with the most parents first" do
+      register_guest(:foo, nil, true)
+      register_guest(:bar, :foo, true)
+      register_guest(:baz, :bar, true)
+      register_guest(:foo2, nil, true)
+      register_guest(:bar2, :foo2, true)
+
+      subject.detect!
+      subject.chain.length.should == 3
+      subject.chain.map(&:name).should == [:baz, :bar, :foo]
+    end
+
+    it "raises an exception if no guest can be detected" do
+      expect { subject.detect! }.
+        to raise_error(Vagrant::Errors::GuestNotDetected)
+    end
+  end
+
+  describe "#ready?" do
+    before(:each) do
+      register_guest(:foo, nil, true)
+    end
+
+    it "should not be ready by default" do
+      subject.ready?.should_not be
+    end
+
+    it "should be ready after detecting" do
+      subject.detect!
+      subject.ready?.should be
+    end
+  end
+end
diff --git a/test/unit/vagrant/machine_test.rb b/test/unit/vagrant/machine_test.rb
index 7a24be9ab..74cdb51c1 100644
--- a/test/unit/vagrant/machine_test.rb
+++ b/test/unit/vagrant/machine_test.rb
@@ -197,6 +197,7 @@ describe Vagrant::Machine do
     let(:communicator) do
       result = double("communicator")
       result.stub(:ready?).and_return(true)
+      result.stub(:test).and_return(false)
       result
     end
 
@@ -212,63 +213,19 @@ describe Vagrant::Machine do
     end
 
     it "should return the configured guest" do
-      test_guest = Class.new(Vagrant.plugin("2", :guest))
+      test_guest = Class.new(Vagrant.plugin("2", :guest)) do
+        def detect?(machine)
+          true
+        end
+      end
 
       register_plugin do |p|
         p.guest(:test) { test_guest }
       end
 
-      config.vm.guest = :test
-
       result = instance.guest
       result.should be_kind_of(test_guest)
     end
-
-    it "should raise an exception if it can't find the configured guest" do
-      config.vm.guest = :bad
-
-      expect { instance.guest }.
-        to raise_error(Vagrant::Errors::VMGuestError)
-    end
-
-    it "should distro dispatch to the most specific guest" do
-      # Create the classes and dispatch the parent into the child
-      guest_parent = Class.new(Vagrant.plugin("2", :guest)) do
-        def distro_dispatch
-          :child
-        end
-      end
-
-      guest_child  = Class.new(Vagrant.plugin("2", :guest))
-
-      # Register the classes
-      register_plugin do |p|
-        p.guest(:parent) { guest_parent }
-        p.guest(:child)  { guest_child }
-      end
-
-      # Test that the result is the child
-      config.vm.guest = :parent
-      instance.guest.should be_kind_of(guest_child)
-    end
-
-    it "should protect against loops in the distro dispatch" do
-      # Create the classes and dispatch the parent into the child
-      guest_parent = Class.new(Vagrant.plugin("2", :guest)) do
-        def distro_dispatch
-          :parent
-        end
-      end
-
-      # Register the classes
-      register_plugin do |p|
-        p.guest(:parent) { guest_parent }
-      end
-
-      # Test that the result is the child
-      config.vm.guest = :parent
-      instance.guest.should be_kind_of(guest_parent)
-     end
   end
 
   describe "setting the ID" do