Render milestone links as references

app/models/milestone.rb

@@ -22,6 +22,7 @@ class Milestone < ActiveRecord::Base
 
   include InternalId
   include Sortable
+  include Referable
   include StripAttribute
 
   belongs_to :project
@@ -61,6 +62,23 @@ class Milestone < ActiveRecord::Base
     end
   end
 
+  def self.reference_pattern
+    nil
+  end
+
+  def self.link_reference_pattern
+    super("milestones", /(?<milestone>\d+)/)
+  end
+
+  def to_reference(from_project = nil)
+    h = Gitlab::Application.routes.url_helpers
+    h.namespace_project_milestone_url(self.project.namespace, self.project, self)
+  end
+
+  def reference_link_text(from_project = nil)
+    %Q{<i class="fa fa-clock-o"></i> }.html_safe + self.title
+  end
+
   def expired?
     if due_date
       due_date.past?

lib/banzai/filter/abstract_reference_filter.rb

@@ -60,6 +60,7 @@ module Banzai
       end
 
       def call
+        if object_class.reference_pattern
           # `#123`
           replace_text_nodes_matching(object_class.reference_pattern) do |content|
             object_link_filter(content, object_class.reference_pattern)
@@ -70,7 +71,9 @@ module Banzai
           replace_link_nodes_with_href(object_class.reference_pattern) do |link, text|
             object_link_filter(link, object_class.reference_pattern, link_text: text)
           end
+        end
 
+        if object_class.link_reference_pattern
           # `http://gitlab.example.com/namespace/project/issues/123`, which is turned into
           # `<a href="http://gitlab.example.com/namespace/project/issues/123">http://gitlab.example.com/namespace/project/issues/123</a>`
           replace_link_nodes_with_text(object_class.link_reference_pattern) do |text|
@@ -83,6 +86,7 @@ module Banzai
             object_link_filter(link, object_class.link_reference_pattern, link_text: text)
           end
         end
+      end
 
       # Replace references (like `!123` for merge requests) in text with links
       # to the referenced object's details page.

lib/banzai/filter/milestone_reference_filter.rb

+require 'banzai'
+
+module Banzai
+  module Filter
+    # HTML filter that replaces milestone references with links.
+    #
+    # This filter supports cross-project references.
+    class MilestoneReferenceFilter < AbstractReferenceFilter
+      def self.object_class
+        Milestone
+      end
+
+      def find_object(project, id)
+        project.milestones.find_by(iid: id)
+      end
+
+      def url_for_object(issue, project)
+        h = Gitlab::Application.routes.url_helpers
+        h.namespace_project_milestone_url(project.namespace, project, milestone,
+                                        only_path: context[:only_path])
+      end
+    end
+  end
+end

lib/banzai/pipeline/gfm_pipeline.rb

@@ -22,6 +22,7 @@ module Banzai
           Filter::CommitRangeReferenceFilter,
           Filter::CommitReferenceFilter,
           Filter::LabelReferenceFilter,
+          Filter::MilestoneReferenceFilter,
 
           Filter::TaskListFilter
         ]

lib/gitlab/reference_extractor.rb

@@ -18,7 +18,7 @@ module Gitlab
       super(text, context.merge(project: project))
     end
 
-    %i(user label merge_request snippet commit commit_range).each do |type|
+    %i(user label milestone merge_request snippet commit commit_range).each do |type|
       define_method("#{type}s") do
         @references[type] ||= references(type, project: project, current_user: current_user)
       end

spec/features/markdown_spec.rb

@@ -212,6 +212,7 @@ describe 'GitLab Markdown', feature: true do
         expect(doc).to reference_commit_ranges
         expect(doc).to reference_commits
         expect(doc).to reference_labels
+        expect(doc).to reference_milestones
       end
     end
 

spec/fixtures/markdown.md.erb

@@ -214,6 +214,14 @@ References should be parseable even inside _<%= merge_request.to_reference %>_ e
 - Ignored in links: [Link to <%= simple_label.to_reference %>](#label-link)
 - Link to label by reference: [Label](<%= label.to_reference %>)
 
+#### MilestoneReferenceFilter
+
+- Milestone: <%= milestone.to_reference %>
+- Milestone in another project: <%= xmilestone.to_reference(project) %>
+- Ignored in code: `<%= milestone.to_reference %>`
+- Ignored in links: [Link to <%= milestone.to_reference %>](#milestone-link)
+- Link to milestone by URL: [Milestone](<%= urls.namespace_project_milestone_url(milestone.project.namespace, milestone.project, milestone) %>)
+
 ### Task Lists
 
 - [ ] Incomplete task 1

spec/lib/banzai/filter/milestone_reference_filter_spec.rb

+require 'spec_helper'
+
+describe Banzai::Filter::MilestoneReferenceFilter, lib: true do
+  include FilterSpecHelper
+
+  let(:project) { create(:project, :public) }
+  let(:milestone)   { create(:milestone, project: project) }
+
+  it 'requires project context' do
+    expect { described_class.call('') }.to raise_error(ArgumentError, /:project/)
+  end
+
+  %w(pre code a style).each do |elem|
+    it "ignores valid references contained inside '#{elem}' element" do
+      exp = act = "<#{elem}>milestone #{milestone.to_reference}</#{elem}>"
+      expect(reference_filter(act).to_html).to eq exp
+    end
+  end
+
+  context 'internal reference' do
+    let(:reference) { milestone.to_reference }
+
+    it 'links to a valid reference' do
+      doc = reference_filter("See #{reference}")
+
+      expect(doc.css('a').first.attr('href')).to eq urls.
+        namespace_project_milestone_url(project.namespace, project, milestone)
+    end
+
+    it 'links with adjacent text' do
+      doc = reference_filter("milestone (#{reference}.)")
+      expect(doc.to_html).to match(/\(<a.+><i.+><\/i> #{Regexp.escape(milestone.title)}<\/a>\.\)/)
+    end
+
+    it 'includes a title attribute' do
+      doc = reference_filter("milestone #{reference}")
+      expect(doc.css('a').first.attr('title')).to eq "Milestone: #{milestone.title}"
+    end
+
+    it 'escapes the title attribute' do
+      milestone.update_attribute(:title, %{"></a>whatever<a title="})
+
+      doc = reference_filter("milestone #{reference}")
+      expect(doc.text).to eq "milestone  #{milestone.title}"
+    end
+
+    it 'includes default classes' do
+      doc = reference_filter("milestone #{reference}")
+      expect(doc.css('a').first.attr('class')).to eq 'gfm gfm-milestone'
+    end
+
+    it 'includes a data-project attribute' do
+      doc = reference_filter("milestone #{reference}")
+      link = doc.css('a').first
+
+      expect(link).to have_attribute('data-project')
+      expect(link.attr('data-project')).to eq project.id.to_s
+    end
+
+    it 'includes a data-milestone attribute' do
+      doc = reference_filter("See #{reference}")
+      link = doc.css('a').first
+
+      expect(link).to have_attribute('data-milestone')
+      expect(link.attr('data-milestone')).to eq milestone.id.to_s
+    end
+
+    it 'adds to the results hash' do
+      result = reference_pipeline_result("milestone #{reference}")
+      expect(result[:references][:milestone]).to eq [milestone]
+    end
+  end
+end

spec/support/markdown_feature.rb

@@ -59,6 +59,10 @@ class MarkdownFeature
     @label ||= create(:label, name: 'awaiting feedback', project: project)
   end
 
+  def milestone
+    @milestone ||= create(:milestone, project: project)
+  end
+
   # Cross-references -----------------------------------------------------------
 
   def xproject
@@ -93,6 +97,10 @@ class MarkdownFeature
     end
   end
 
+  def xmilestone
+    @xmilestone ||= create(:milestone, project: xproject)
+  end
+
   def urls
     Gitlab::Application.routes.url_helpers
   end

spec/support/matchers/markdown_matchers.rb

@@ -130,6 +130,15 @@ module MarkdownMatchers
     end
   end
 
+  # MilestoneReferenceFilter
+  matcher :reference_milestones do
+    set_default_markdown_messages
+
+    match do |actual|
+      expect(actual).to have_selector('a.gfm.gfm-milestone', count: 3)
+    end
+  end
+
   # TaskListFilter
   matcher :parse_task_lists do
     set_default_markdown_messages