Fix URL builder to use GitlabRoutingHelper

lib/gitlab/url_builder.rb

 module Gitlab
   class UrlBuilder
     include Rails.application.routes.url_helpers
+    include GitlabRoutingHelper
 
     def initialize(type)
       @type = type
@@ -9,27 +10,22 @@ module Gitlab
     def build(id)
       case @type
       when :issue
-        issue_url(id)
+        build_issue_url(id)
       when :merge_request
-        merge_request_url(id)
+        build_merge_request_url(id)
       end
     end
 
     private
 
-    def issue_url(id)
+    def build_issue_url(id)
       issue = Issue.find(id)
-      namespace_project_issue_url(namespace_id: issue.project.namespace,
-                                  id: issue.iid,
-                                  project_id: issue.project,
-                                  host: Gitlab.config.gitlab['url'])
+      issue_url(issue, host: Gitlab.config.gitlab['url'])
     end
 
-    def merge_request_url(id)
+    def build_merge_request_url(id)
       merge_request = MergeRequest.find(id)
-      project_merge_request_url(id: merge_request.id,
-                                project_id: merge_request.project,
-                                host: Gitlab.config.gitlab['url'])
+      merge_request_url(merge_request, host: Gitlab.config.gitlab['url'])
     end
   end
 end

spec/lib/gitlab/url_builder_spec.rb

@@ -13,7 +13,7 @@ describe Gitlab::UrlBuilder do
     it 'returns the merge request url' do
       merge_request = create(:merge_request)
       url = Gitlab::UrlBuilder.new(:merge_request).build(merge_request.id)
-      expect(url).to eq "#{Settings.gitlab['url']}/#{merge_request.project.to_param}/merge_requests/#{merge_request.id}"
+      expect(url).to eq "#{Settings.gitlab['url']}/#{merge_request.project.path_with_namespace}/merge_requests/#{merge_request.iid}"
     end
   end
 end