Adding a "none" node source, which will be the default node source and will just return an empty node.

lib/puppet/configuration.rb

@@ -549,7 +549,9 @@ module Puppet
     setdefaults(:parser,
         :typecheck => [true, "Whether to validate types during parsing."],
         :paramcheck => [true, "Whether to validate parameters during parsing."],
-        :node_source => ["", "Where to look for node configuration information.
+        :node_source => ["none", "Where to look for node configuration information.
+            The default node source, ``none``, just returns a node with its facts
+            filled in, which is required for normal functionality.
             See the `NodeSourceReference`:trac: for more information."]
     )
     

lib/puppet/node_source/none.rb

@@ -0,0 +1,10 @@
+Puppet::Network::Handler::Node.newnode_source(:none, :fact_merge => true) do
+    desc "Always return an empty node object.  This is the node source you should
+        use when you don't have some other, functional source you want to use,
+        as the compiler will not work without this node information."
+
+    # Just return an empty node.
+    def nodesearch(name)
+        newnode(name)
+    end
+end

test/network/handler/node.rb

@@ -529,6 +529,24 @@ class TestNodeSources < Test::Unit::TestCase
         assert_equal(%w{one two three four five}.sort, node.classes.sort, "node classes were not set correctly with the top node")
         assert_equal({"base" => "true", "center" => "boo", "master" => "far"}, node.parameters, "node parameters were not set correctly with the top node")
     end
+
+    # Make sure we always get a node back from the 'none' nodesource.
+    def test_nodesource_none
+        source = Node.node_source(:none)
+        assert(source, "Could not find 'none' node source")
+        searcher = mk_searcher(:none)
+        assert(searcher.fact_merge?, "'none' node source does not merge facts")
+
+        # Run a couple of node names through it
+        node = nil
+        %w{192.168.0.1 0:0:0:3:a:f host host.domain.com}.each do |name|
+            assert_nothing_raised("Could not create an empty node with name '%s'" % name) do
+                node = searcher.nodesearch(name)
+            end
+            assert_instance_of(SimpleNode, node, "Did not get a simple node back for %s" % name)
+            assert_equal(name, node.name, "Name was not set correctly")
+        end
+    end
 end
 
 class LdapNodeTest < PuppetTest::TestCase