core: Add synced_folder plugin type

lib/vagrant/plugin/v2.rb

@@ -17,6 +17,7 @@ module Vagrant
       autoload :Plugin, "vagrant/plugin/v2/plugin"
       autoload :Provider, "vagrant/plugin/v2/provider"
       autoload :Provisioner, "vagrant/plugin/v2/provisioner"
+      autoload :SyncedFolder, "vagrant/plugin/v2/synced_folder"
     end
   end
 end

lib/vagrant/plugin/v2/components.rb

@@ -32,6 +32,11 @@ module Vagrant
         # @return [Hash<Symbol, Registry>]
         attr_reader :providers
 
+        # This contains all the synced folder implementations by name.
+        #
+        # @return [Registry<Symbol, Class>]
+        attr_reader :synced_folders
+
         def initialize
           # The action hooks hash defaults to []
           @action_hooks = Hash.new { |h, k| h[k] = [] }
@@ -40,6 +45,7 @@ module Vagrant
           @guests  = Registry.new
           @guest_capabilities = Hash.new { |h, k| h[k] = Registry.new }
           @providers = Registry.new
+          @synced_folders = Registry.new
         end
       end
     end

lib/vagrant/plugin/v2/plugin.rb

@@ -194,6 +194,19 @@ module Vagrant
           data[:provisioners]
         end
 
+        # Registers additional synced folder implementations.
+        #
+        # @param [String] name Name of the implementation.
+        # @param [Integer] priority The priority of the implementation,
+        # higher (big) numbers are tried before lower (small) numbers.
+        def self.synced_folder(name, priority=10, &block)
+          components.synced_folders.register(name.to_sym) do
+            [block.call, priority]
+          end
+
+          nil
+        end
+
         # Returns the internal data associated with this plugin. This
         # should NOT be called by the general public.
         #

lib/vagrant/plugin/v2/synced_folder.rb

@@ -0,0 +1,17 @@
+module Vagrant
+  module Plugin
+    module V2
+      # This is the base class for a synced folder implementation.
+      class SyncedFolder
+        def usable?(machine)
+        end
+
+        def prepare(machine)
+        end
+
+        def enable(machine)
+        end
+      end
+    end
+  end
+end

test/unit/vagrant/plugin/v2/components_test.rb

@@ -3,15 +3,19 @@ require File.expand_path("../../../../base", __FILE__)
 require "vagrant/registry"
 
 describe Vagrant::Plugin::V2::Components do
-  let(:instance) { described_class.new }
+  subject { described_class.new }
+
+  it "should have synced folders" do
+    subject.synced_folders.should be_kind_of(Vagrant::Registry)
+  end
 
   describe "configs" do
     it "should have configs" do
-      instance.configs.should be_kind_of(Hash)
+      subject.configs.should be_kind_of(Hash)
     end
 
     it "should default the values to registries" do
-      instance.configs[:i_probably_dont_exist].should be_kind_of(Vagrant::Registry)
+      subject.configs[:i_probably_dont_exist].should be_kind_of(Vagrant::Registry)
     end
   end
 end

test/unit/vagrant/plugin/v2/plugin_test.rb

@@ -278,6 +278,42 @@ describe Vagrant::Plugin::V2::Plugin do
     end
   end
 
+  describe "synced folders" do
+    it "should register implementations" do
+      plugin = Class.new(described_class) do
+        synced_folder("foo") { "bar" }
+      end
+
+      plugin.components.synced_folders[:foo].should == ["bar", 10]
+    end
+
+    it "should be able to specify priorities" do
+      plugin = Class.new(described_class) do
+        synced_folder("foo", 50) { "bar" }
+      end
+
+      plugin.components.synced_folders[:foo].should == ["bar", 50]
+    end
+
+    it "should lazily register implementations" do
+      # Below would raise an error if the value of the config class was
+      # evaluated immediately. By asserting that this does not raise an
+      # error, we verify that the value is actually lazily loaded
+      plugin = nil
+      expect {
+        plugin = Class.new(described_class) do
+          synced_folder("foo") { raise StandardError, "FAIL!" }
+        end
+      }.to_not raise_error
+
+      # Now verify when we actually get the configuration key that
+      # a proper error is raised.
+      expect {
+        plugin.components.synced_folders[:foo]
+      }.to raise_error(StandardError)
+    end
+  end
+
   describe "plugin registration" do
     let(:manager) { described_class.manager }