Fix issues/MRs filter when ordering by milestone due date

app/finders/issuable_finder.rb

@@ -253,9 +253,9 @@ class IssuableFinder
         items = items.where(milestone_id: [-1, nil])
       elsif filter_by_upcoming_milestone?
         upcoming_ids = Milestone.upcoming_ids_by_projects(projects)
-        items = items.joins(:milestone).where(milestone_id: upcoming_ids)
+        items = items.left_joins_milestones.where(milestone_id: upcoming_ids)
       else
-        items = items.joins(:milestone).where(milestones: { title: params[:milestone_title] })
+        items = items.left_joins_milestones.where(milestones: { title: params[:milestone_title] })
 
         if projects
           items = items.where(milestones: { project_id: projects })

app/models/concerns/issuable.rb

@@ -35,10 +35,12 @@ module Issuable
     scope :only_opened, -> { with_state(:opened) }
     scope :only_reopened, -> { with_state(:reopened) }
     scope :closed, -> { with_state(:closed) }
+
+    scope :left_joins_milestones,    -> { joins("LEFT OUTER JOIN milestones ON #{table_name}.milestone_id = milestones.id") }
     scope :order_milestone_due_desc, -> { outer_join_milestone.reorder('milestones.due_date IS NULL ASC, milestones.due_date DESC, milestones.id DESC') }
     scope :order_milestone_due_asc, -> { outer_join_milestone.reorder('milestones.due_date IS NULL ASC, milestones.due_date ASC, milestones.id ASC') }
-    scope :without_label, -> { joins("LEFT OUTER JOIN label_links ON label_links.target_type = '#{name}' AND label_links.target_id = #{table_name}.id").where(label_links: { id: nil }) }
 
+    scope :without_label, -> { joins("LEFT OUTER JOIN label_links ON label_links.target_type = '#{name}' AND label_links.target_id = #{table_name}.id").where(label_links: { id: nil }) }
     scope :join_project, -> { joins(:project) }
     scope :references_project, -> { references(:project) }
     scope :non_archived, -> { join_project.where(projects: { archived: false }) }

spec/models/concerns/issuable_spec.rb

 require 'spec_helper'
 
 describe Issue, "Issuable" do
-  let(:issue) { create(:issue) }
+  let!(:issue) { create(:issue) }
   let(:user) { create(:user) }
 
   describe "Associations" do
@@ -114,6 +114,45 @@ describe Issue, "Issuable" do
     end
   end
 
+  describe "#sort" do
+    #Correct order is:
+    #Issues/MRs with milestones ordered by date
+    #Issues/MRs with milestones without dates
+    #Issues/MRs without milestones
+    let(:project) { issue.project }
+    let!(:early_milestone) { create(:milestone, project: project, due_date: 10.days.from_now) }
+    let!(:late_milestone) { create(:milestone, project: project, due_date: 30.days.from_now) }
+    let!(:issue1) { create(:issue, project: project, milestone: early_milestone) }
+    let!(:issue2) { create(:issue, project: project, milestone: late_milestone) }
+    let!(:issue3) { create(:issue, project: project) }
+
+
+    context "milestone due later" do
+      subject { Issue.where(project_id: project.id).order_milestone_due_desc }
+      before  { @issues = subject }
+
+      it "puts issues with nil values at the end of collection" do
+        expect(@issues.first).to eq(issue2)
+        expect(@issues.second).to eq(issue1)
+        expect(@issues.third).to eq(issue)
+        expect(@issues.fourth).to eq(issue3)
+      end
+    end
+
+    context "milestone due soon" do
+      subject { Issue.where(project_id: project.id).order_milestone_due_asc }
+      before  { @issues = subject }
+
+      it "puts issues with nil values at the end of collection" do
+        expect(@issues.first).to eq(issue1)
+        expect(@issues.second).to eq(issue2)
+        expect(@issues.third).to eq(issue)
+        expect(@issues.fourth).to eq(issue3)
+      end
+    end
+  end
+
+
   describe '#subscribed?' do
     context 'user is not a participant in the issue' do
       before { allow(issue).to receive(:participants).with(user).and_return([]) }