Add a note when an Issue or Merge Request's title changes

CHANGELOG

@@ -15,6 +15,7 @@ v 7.12.0 (unreleased)
   - Default extention for wiki pages is now .md instead of .markdown (Jeroen van Baarsen)
   - Add validation to wiki page creation (only [a-zA-Z0-9/_-] are allowed) (Jeroen van Baarsen)
   - Fix new/empty milestones showing 100% completion value (Jonah Bishop)
+  - Add a note when an Issue or Merge Request's title changes
 
 v 7.11.2
   - no changes

app/services/issuable_base_service.rb

@@ -15,4 +15,9 @@ class IssuableBaseService < BaseService
     SystemNoteService.change_label(
       issuable, issuable.project, current_user, added_labels, removed_labels)
   end
+
+  def create_title_change_note(issuable, old_title)
+    SystemNoteService.change_title(
+      issuable, issuable.project, current_user, old_title)
+  end
 end

app/services/issues/update_service.rb

@@ -37,6 +37,10 @@ module Issues
           notification_service.reassigned_issue(issue, current_user)
         end
 
+        if issue.previous_changes.include?('title')
+          create_title_change_note(issue, issue.previous_changes['title'].first)
+        end
+
         issue.notice_added_references(issue.project, current_user)
         execute_hooks(issue, 'update')
       end

app/services/merge_requests/update_service.rb

@@ -50,6 +50,10 @@ module MergeRequests
           notification_service.reassigned_merge_request(merge_request, current_user)
         end
 
+        if merge_request.previous_changes.include?('title')
+          create_title_change_note(merge_request, merge_request.previous_changes['title'].first)
+        end
+
         merge_request.notice_added_references(merge_request.project, current_user)
         execute_hooks(merge_request, 'update')
       end

app/services/system_note_service.rb

@@ -130,6 +130,25 @@ class SystemNoteService
     create_note(noteable: noteable, project: project, author: author, note: body)
   end
 
+  # Called when the title of a Noteable is changed
+  #
+  # noteable  - Noteable object that responds to `title`
+  # project   - Project owning noteable
+  # author    - User performing the change
+  # old_title - Previous String title
+  #
+  # Example Note text:
+  #
+  #   "Title changed from **Old** to **New**"
+  #
+  # Returns the created Note object
+  def self.change_title(noteable, project, author, old_title)
+    return unless noteable.respond_to?(:title)
+
+    body = "Title changed from **#{old_title}** to **#{noteable.title}**"
+    create_note(noteable: noteable, project: project, author: author, note: body)
+  end
+
   # Called when a Mentionable references a Noteable
   #
   # noteable  - Noteable object being referenced

spec/services/issues/update_service_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 describe Issues::UpdateService do
   let(:user) { create(:user) }
   let(:user2) { create(:user) }
-  let(:issue) { create(:issue) }
+  let(:issue) { create(:issue, title: 'Old title') }
   let(:label) { create(:label) }
   let(:project) { issue.project }
 
@@ -12,7 +12,7 @@ describe Issues::UpdateService do
     project.team << [user2, :developer]
   end
 
-  describe :execute do
+  describe 'execute' do
     context "valid params" do
       before do
         opts = {
@@ -40,15 +40,32 @@ describe Issues::UpdateService do
         expect(email.subject).to include(issue.title)
       end
 
+      def find_note(starting_with)
+        @issue.notes.find do |n|
+          n && n.note.start_with?(starting_with)
+        end
+      end
+
       it 'should create system note about issue reassign' do
-        note = @issue.notes.last
+        note = find_note('Reassigned to')
+
+        expect(note).not_to be_nil
         expect(note.note).to include "Reassigned to \@#{user2.username}"
       end
 
       it 'should create system note about issue label edit' do
-        note = @issue.notes[1]
+        note = find_note('Added ~')
+
+        expect(note).not_to be_nil
         expect(note.note).to include "Added ~#{label.id} label"
       end
+
+      it 'creates system note about title change' do
+        note = find_note('Title changed')
+
+        expect(note).not_to be_nil
+        expect(note.note).to eq 'Title changed from **Old title** to **New title**'
+      end
     end
   end
 end

spec/services/merge_requests/update_service_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 describe MergeRequests::UpdateService do
   let(:user) { create(:user) }
   let(:user2) { create(:user) }
-  let(:merge_request) { create(:merge_request, :simple) }
+  let(:merge_request) { create(:merge_request, :simple, title: 'Old title') }
   let(:project) { merge_request.project }
   let(:label) { create(:label) }
 
@@ -12,7 +12,7 @@ describe MergeRequests::UpdateService do
     project.team << [user2, :developer]
   end
 
-  describe :execute do
+  describe 'execute' do
     context 'valid params' do
       let(:opts) do
         {
@@ -51,15 +51,32 @@ describe MergeRequests::UpdateService do
         expect(email.subject).to include(merge_request.title)
       end
 
+      def find_note(starting_with)
+        @merge_request.notes.find do |n|
+          n && n.note.start_with?(starting_with)
+        end
+      end
+
       it 'should create system note about merge_request reassign' do
-        note = @merge_request.notes.last
+        note = find_note('Reassigned to')
+
+        expect(note).not_to be_nil
         expect(note.note).to include "Reassigned to \@#{user2.username}"
       end
 
       it 'should create system note about merge_request label edit' do
-        note = @merge_request.notes[1]
+        note = find_note('Added ~')
+
+        expect(note).not_to be_nil
         expect(note.note).to include "Added ~#{label.id} label"
       end
+
+      it 'creates system note about title change' do
+        note = find_note('Title changed')
+
+        expect(note).not_to be_nil
+        expect(note.note).to eq 'Title changed from **Old title** to **New title**'
+      end
     end
   end
 end

spec/services/system_note_service_spec.rb

@@ -207,6 +207,27 @@ describe SystemNoteService do
     end
   end
 
+  describe '.change_title' do
+    subject { described_class.change_title(noteable, project, author, 'Old title') }
+
+    context 'when noteable responds to `title`' do
+      it_behaves_like 'a system note'
+
+      it 'sets the note text' do
+        expect(subject.note).
+          to eq "Title changed from **Old title** to **#{noteable.title}**"
+      end
+    end
+
+    context 'when noteable does not respond to `title' do
+      let(:noteable) { double('noteable') }
+
+      it 'returns nil' do
+        expect(subject).to be_nil
+      end
+    end
+  end
+
   describe '.cross_reference' do
     subject { described_class.cross_reference(noteable, mentioner, author) }