Add #length and #size methods to Registry

lib/vagrant/registry.rb

@@ -49,6 +49,14 @@ module Vagrant
       end
     end
 
+    # Return the number of elements in this registry.
+    #
+    # @return [Fixnum]
+    def length
+      @items.keys.length
+    end
+    alias_method :size, :length
+
     # Merge one registry with another and return a completely new
     # registry. Note that the result cache is completely busted, so
     # any gets on the new registry will result in a cache miss.

test/unit/vagrant/registry_test.rb

@@ -90,6 +90,28 @@ describe Vagrant::Registry do
     expect(result["bar"]).to eq("barvalue")
   end
 
+  describe "#length" do
+    it "should return 0 when the registry is empty" do
+      expect(instance.length).to eq(0)
+    end
+
+    it "should return the number of items in the registry" do
+      instance.register("foo") { }
+      instance.register("bar") { }
+
+      expect(instance.length).to eq(2)
+    end
+  end
+
+  describe "#size" do
+    it "should be an alias to #length" do
+      size = described_class.instance_method(:size)
+      length = described_class.instance_method(:length)
+
+      expect(size).to eq(length)
+    end
+  end
+
   describe "merging" do
     it "should merge in another registry" do
       one = described_class.new