Test Tempdir class cleans itself up

test/support/tempdir.rb

@@ -3,9 +3,6 @@ require 'tempfile'
 
 # This class provides an easy way of creating a temporary
 # directory and having it removed when the application exits.
-#
-# TODO: This class doesn't currently delete the temporary
-# directory on exit.
 class Tempdir
   attr_reader :path
 
@@ -25,10 +22,22 @@ class Tempdir
         @path = nil
       end
     end
+
+    # Setup a finalizer to delete the directory. This is the same way
+    # that Tempfile and friends do this...
+    @cleanup_proc = lambda do
+      FileUtils.rm_rf(@path) if File.directory?(@path)
+    end
+
+    ObjectSpace.define_finalizer(self, @cleanup_proc)
   end
 
   # This deletes the temporary directory.
   def unlink
-    FileUtils.rm_rf(@path)
+    # Delete the directory
+    @cleanup_proc.call
+
+    # Undefine the finalizer since we're all cleaned up
+    ObjectSpace.undefine_finalizer(self)
   end
 end