get thnads tests to work

test/graph_helper.rb

@@ -0,0 +1,22 @@
+require 'gritty'
+
+def dump(obj, name)
+  g = digraph do
+    graph_attribs << 'bgcolor=black'
+
+    node_attribs << 'color=white'
+    node_attribs << 'penwidth=2'
+    node_attribs << 'fontcolor=white'
+    node_attribs << 'labelloc=c'
+    node_attribs << 'fontname="Courier New"'
+    node_attribs << 'fontsize=36'
+
+    edge_attribs << 'color=white'
+    edge_attribs << 'penwidth=2'
+
+    builder = Gritty::NodeBuilder.new self
+    builder.build obj, 'root'
+
+    save name, 'pdf'
+  end
+end