Unknown keys return a DummyConfig rather than OpenStruct

lib/vagrant/config/v1.rb

@@ -1,6 +1,7 @@
 module Vagrant
   module Config
     module V1
+      autoload :DummyConfig, "vagrant/config/v1/dummy_config"
       autoload :Loader, "vagrant/config/v1/loader"
       autoload :Root,   "vagrant/config/v1/root"
     end

lib/vagrant/config/v1/dummy_config.rb

@@ -0,0 +1,13 @@
+module Vagrant
+  module Config
+    module V1
+      # This is a configuration object that can have anything done
+      # to it. Anything, and it just appears to keep working.
+      class DummyConfig
+        def method_missing(name, *args, &block)
+          DummyConfig.new
+        end
+      end
+    end
+  end
+end

lib/vagrant/config/v1/root.rb

@@ -1,4 +1,3 @@
-require "ostruct"
 require "set"
 
 module Vagrant
@@ -31,7 +30,7 @@ module Vagrant
           else
             # Record access to a missing key as an error
             @missing_key_calls.add(name.to_s)
-            return OpenStruct.new
+            return DummyConfig.new
           end
         end
 

test/unit/vagrant/config/v1/dummy_config_test.rb

@@ -0,0 +1,24 @@
+require File.expand_path("../../../../base", __FILE__)
+
+describe Vagrant::Config::V1::DummyConfig do
+  it "should allow attribute setting" do
+    expect { subject.foo = :bar }.
+      to_not raise_error
+  end
+
+  it "should allow method calls that return more DummyConfigs" do
+    subject.foo.should be_kind_of(described_class)
+  end
+
+  it "should allow hash access" do
+    expect { subject[:foo] }.
+      to_not raise_error
+
+    subject[:foo].should be_kind_of(described_class)
+  end
+
+  it "should allow setting hash values" do
+    expect { subject[:foo] = :bar }.
+      to_not raise_error
+  end
+end