Add group milestones to dashboard milestone page

app/controllers/dashboard/milestones_controller.rb

@@ -21,8 +21,19 @@ class Dashboard::MilestonesController < Dashboard::ApplicationController
 
   private
 
+  def group_milestones
+    groups = GroupsFinder.new(current_user, all_available: true).execute
+
+    DashboardGroupMilestone.build_collection(groups)
+  end
+
+  # See [#39545](https://gitlab.com/gitlab-org/gitlab-ce/issues/39545) for info about the deprecation of dynamic milestones
+  def dynamic_milestones
+    DashboardMilestone.build_collection(@projects, params)
+  end
+
   def milestones
-    @milestones = DashboardMilestone.build_collection(@projects, params)
+    @milestones = group_milestones + dynamic_milestones
   end
 
   def milestone

app/helpers/milestones_helper.rb

@@ -233,4 +233,12 @@ module MilestonesHelper
       group_milestone_path(@group, milestone.iid, milestone: params)
     end
   end
+
+  def group_or_dashboard_milestone_path(milestone)
+    if milestone.group_milestone?
+      group_milestone_path(milestone.group, milestone.iid, milestone: { title: milestone.title })
+    else
+      dashboard_milestone_path(milestone.safe_title, title: milestone.title)
+    end
+  end
 end

app/models/dashboard_group_milestone.rb

+# frozen_string_literal: true
+# Dashboard Group Milestones are milestones that allow us to pull more info out for the UI that the Milestone object doesn't allow for
+class DashboardGroupMilestone < GlobalMilestone
+  extend ::Gitlab::Utils::Override
+
+  attr_reader :group_name
+
+  override :initialize
+  def initialize(milestone)
+    super(milestone.title, Array(milestone))
+
+    @group_name = milestone.group.full_name
+  end
+
+  def self.build_collection(groups)
+    MilestonesFinder.new(group_ids: groups.pluck(:id)).execute.map { |m| new(m) }
+  end
+
+  override :group_milestone?
+  def group_milestone?
+    @first_milestone.group_milestone?
+  end
+
+  override :milestoneish_ids
+  def milestoneish_ids
+    milestones.map(&:id)
+  end
+
+  def group
+    @first_milestone.group
+  end
+
+  def iid
+    @first_milestone.iid
+  end
+end

app/models/global_milestone.rb

 # frozen_string_literal: true
-
+# Global Milestones are milestones that can be shared across multiple projects
 class GlobalMilestone
   include Milestoneish
 

app/models/group_milestone.rb

 # frozen_string_literal: true
-
+# Group Milestones are milestones that can be shared among many projects within the same group
 class GroupMilestone < GlobalMilestone
   attr_accessor :group
 

app/views/dashboard/milestones/_milestone.html.haml

 = render 'shared/milestones/milestone',
-          milestone_path: dashboard_milestone_path(milestone.safe_title, title: milestone.title),
+          milestone_path: group_or_dashboard_milestone_path(milestone),
           issues_path: issues_dashboard_path(milestone_title: milestone.title),
           merge_requests_path: merge_requests_dashboard_path(milestone_title: milestone.title),
           milestone: milestone,

changelogs/unreleased/cr-add-group-milestone-to-dashboard.yml

+---
+title: Adds the ability to view group milestones on the dashboard milestone page.
+merge_request: 20618
+author:
+type: fixed

changelogs/unreleased/cr-add-path-of-group-milestone.yml

+---
+title: Adds the project and group name to the return type for project and group milestones.
+merge_request: 20890
+author:
+type: changed

spec/controllers/dashboard/milestones_controller_spec.rb

@@ -2,8 +2,10 @@ require 'spec_helper'
 
 describe Dashboard::MilestonesController do
   let(:project) { create(:project) }
+  let(:group) { create(:group) }
   let(:user) { create(:user) }
   let(:project_milestone) { create(:milestone, project: project) }
+  let(:group_milestone) { create(:milestone, group: group) }
   let(:milestone) do
     DashboardMilestone.build(
       [project],
@@ -11,13 +13,17 @@ describe Dashboard::MilestonesController do
     )
   end
   let(:issue) { create(:issue, project: project, milestone: project_milestone) }
+  let(:group_issue) { create(:issue, milestone: group_milestone) }
+
   let!(:label) { create(:label, project: project, title: 'Issue Label', issues: [issue]) }
+  let!(:group_label) { create(:group_label, group: group, title: 'Group Issue Label', issues: [group_issue]) }
   let!(:merge_request) { create(:merge_request, source_project: project, target_project: project, milestone: project_milestone) }
   let(:milestone_path) { dashboard_milestone_path(milestone.safe_title, title: milestone.title) }
 
   before do
     sign_in(user)
     project.add_maintainer(user)
+    group.add_developer(user)
   end
 
   it_behaves_like 'milestone tabs'
@@ -35,4 +41,15 @@ describe Dashboard::MilestonesController do
       expect(response).to have_gitlab_http_status(200)
     end
   end
+
+  describe "#index" do
+    it 'should contain group and project milestones' do
+      get :index, format: :json
+
+      expect(response).to have_gitlab_http_status(200)
+      expect(json_response.size).to eq(2)
+      expect(json_response.map { |i| i["first_milestone"]["id"] }).to include(group_milestone.id, project_milestone.id)
+      expect(json_response.map { |i| i["group_name"] }).to include(group.name)
+    end
+  end
 end