+ ##
+ # yields the relation with the given +id+ (and optional +version+
+ # to read from the history tables) into the block. the parsed XML
+ # doc is returned.
+ def with_relation(id, ver = nil)
+ if ver.nil?
+ get :read, :id => id
+ else
+ with_controller(OldRelationController.new) do
+ get :version, :id => id, :version => ver
+ end
+ end
+ assert_response :success
+ yield xml_parse(@response.body)
+ end
+
+ ##
+ # updates the relation (XML) +rel+ and
+ # yields the new version of that relation into the block.
+ # the parsed XML doc is retured.
+ def with_update(rel)
+ rel_id = rel.find("//osm/relation").first["id"].to_i
+ content rel
+ put :update, :id => rel_id
+ assert_response :success, "can't update relation: #{@response.body}"
+ version = @response.body.to_i
+
+ # now get the new version
+ get :read, :id => rel_id
+ assert_response :success
+ new_rel = xml_parse(@response.body)
+
+ yield new_rel
+
+ return version
+ end
+
+ ##
+ # updates the relation (XML) +rel+ via the diff-upload API and
+ # yields the new version of that relation into the block.
+ # the parsed XML doc is retured.
+ def with_update_diff(rel)
+ rel_id = rel.find("//osm/relation").first["id"].to_i
+ cs_id = rel.find("//osm/relation").first['changeset'].to_i
+ version = nil
+
+ with_controller(ChangesetController.new) do
+ doc = OSM::API.new.get_xml_doc
+ change = XML::Node.new 'osmChange'
+ doc.root = change
+ modify = XML::Node.new 'modify'
+ change << modify
+ modify << doc.import(rel.find("//osm/relation").first)
+
+ content doc.to_s
+ post :upload, :id => cs_id
+ assert_response :success, "can't upload diff relation: #{@response.body}"
+ version = xml_parse(@response.body).find("//diffResult/relation").first["new_version"].to_i
+ end
+
+ # now get the new version
+ get :read, :id => rel_id
+ assert_response :success
+ new_rel = xml_parse(@response.body)
+
+ yield new_rel
+
+ return version
+ end
+
+ ##
+ # returns a k->v hash of tags from an xml doc
+ def get_tags_as_hash(a)
+ a.find("//osm/relation/tag").inject({}) do |h,v|
+ h[v['k']] = v['v']
+ h
+ end
+ end
+
+ ##
+ # assert that all tags on relation documents +a+ and +b+
+ # are equal
+ def assert_tags_equal(a, b)
+ # turn the XML doc into tags hashes
+ a_tags = get_tags_as_hash(a)
+ b_tags = get_tags_as_hash(b)
+
+ assert_equal a_tags.keys, b_tags.keys, "Tag keys should be identical."
+ a_tags.each do |k, v|
+ assert_equal v, b_tags[k],
+ "Tags which were not altered should be the same. " +
+ "#{a_tags.inspect} != #{b_tags.inspect}"
+ end
+ end
+