improve ordering sql for milestones

app/models/concerns/issuable.rb

@@ -37,8 +37,8 @@ module Issuable
     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, -> { left_joins_milestones.reorder('CASE WHEN milestones.due_date IS NULL then 0 ELSE 1 END DESC, CASE WHEN milestones.id IS NULL then 0 ELSE 1 END DESC, milestones.due_date DESC') }
-    scope :order_milestone_due_asc,  -> { left_joins_milestones.reorder('CASE WHEN milestones.due_date IS NULL then 1 ELSE 0 END ASC, CASE WHEN milestones.id IS NULL then 1 ELSE 0 END ASC, milestones.due_date ASC') }
+    scope :order_milestone_due_desc, -> { left_joins_milestones.reorder('milestones.due_date IS NULL, milestones.id IS NULL, milestones.due_date DESC') }
+    scope :order_milestone_due_asc,  -> { left_joins_milestones.reorder('milestones.due_date IS NULL, milestones.id IS NULL, milestones.due_date 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 :join_project, -> { joins(:project) }

spec/models/concerns/issuable_spec.rb

@@ -115,13 +115,15 @@ describe Issue, "Issuable" do
   end
 
   describe "#sort" do
+    let(:project) { build_stubbed(:empty_project) }
+
+    context "by milestone due date" do
       #Correct order is:
       #Issues/MRs with milestones ordered by date
       #Issues/MRs with milestones without dates
       #Issues/MRs without milestones
 
-    let!(:issue) { create(:issue) }
-    let(:project) { issue.project }
+      let!(:issue) { create(:issue, project: 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) }
@@ -129,27 +131,14 @@ describe Issue, "Issuable" do
       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)
+      it "sorts desc" do
+        issues = project.issues.sort('milestone_due_desc')
+        expect(issues).to match_array([issue2, issue1, issue, 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)
+      it "sorts asc" do
+        issues = project.issues.sort('milestone_due_asc')
+        expect(issues).to match_array([issue1, issue2, issue, issue3])
       end
     end
   end