Added tests for changeset upload code. Refactored diff reading code and put it into /lib. Changed the route of a changeset upload to explicitly refer to the changeset it applies to (i.e: resource).

app/models/node.rb

@@ -75,20 +75,25 @@ class Node < ActiveRecord::Base
   def self.from_xml_node(pt, create=false)
     node = Node.new
     
-    node.version = pt['version'].to_i
     node.lat = pt['lat'].to_f
     node.lon = pt['lon'].to_f
     node.changeset_id = pt['changeset'].to_i
 
     return nil unless node.in_world?
 
+    # version must be present unless creating
+    return nil unless create or not pt['version'].nil?
+    node.version = pt['version'].to_i
+
     unless create
       if pt['id'] != '0'
         node.id = pt['id'].to_i
       end
     end
 
-    node.visible = pt['visible'] and pt['visible'] == 'true'
+    # visible if it says it is, or as the default if the attribute
+    # is missing.
+    node.visible = pt['visible'].nil? or pt['visible'] == 'true'
 
     if create
       node.timestamp = Time.now
@@ -235,4 +240,11 @@ class Node < ActiveRecord::Base
     @tags[k] = v
   end
 
+  ##
+  # dummy method to make the interfaces of node, way and relation
+  # more consistent.
+  def fix_placeholders!(id_map)
+    # nodes don't refer to anything, so there is nothing to do here
+  end
+
 end

app/models/relation.rb

@@ -320,4 +320,22 @@ class Relation < ActiveRecord::Base
   def tags_as_hash
     return self.tags
   end
+
+  ##
+  # if any members are referenced by placeholder IDs (i.e: negative) then
+  # this calling this method will fix them using the map from placeholders 
+  # to IDs +id_map+. 
+  def fix_placeholders!(id_map)
+    self.members.map! do |type, id, role|
+      old_id = id.to_i
+      if old_id < 0
+        new_id = id_map[type.to_sym][old_id]
+        raise "invalid placeholder" if new_id.nil?
+        [type, new_id, role]
+      else
+        [type, id, role]
+      end
+    end
+  end
+
 end

app/models/way.rb

@@ -299,4 +299,21 @@ class Way < ActiveRecord::Base
   def tags_as_hash
     return self.tags
   end
+
+  ##
+  # if any referenced nodes are placeholder IDs (i.e: are negative) then
+  # this calling this method will fix them using the map from placeholders 
+  # to IDs +id_map+. 
+  def fix_placeholders!(id_map)
+    self.nds.map! do |node_id|
+      if node_id < 0
+        new_id = id_map[:node][node_id]
+        raise "invalid placeholder for #{node_id.inspect}: #{new_id.inspect}" if new_id.nil?
+        new_id
+      else
+        node_id
+      end
+    end
+  end
+
 end