Fix project dashboard showing the wrong timestamps

Use the max of the `last_activity_at` and `last_repository_updated_at`
columns. The latter is updated only when a push happens, but the former is
updated whenever any activity (e.g. issue creation) happens.

Closes #27181

app/models/project.rb

@@ -274,7 +274,8 @@ class Project < ActiveRecord::Base
   scope :without_storage_feature, ->(feature) { where('storage_version < :version OR storage_version IS NULL', version: HASHED_STORAGE_FEATURES[feature]) }
   scope :with_unmigrated_storage, -> { where('storage_version < :version OR storage_version IS NULL', version: LATEST_STORAGE_VERSION) }
 
-  scope :sorted_by_activity, -> { reorder(last_activity_at: :desc) }
+  # last_activity_at is throttled every minute, but last_repository_updated_at is updated with every push
+  scope :sorted_by_activity, -> { reorder("GREATEST(COALESCE(last_activity_at, '1970-01-01'), COALESCE(last_repository_updated_at, '1970-01-01')) DESC") }
   scope :sorted_by_stars, -> { reorder('projects.star_count DESC') }
 
   scope :in_namespace, ->(namespace_ids) { where(namespace_id: namespace_ids) }
@@ -776,7 +777,7 @@ class Project < ActiveRecord::Base
   end
 
   def last_activity_date
-    last_repository_updated_at || last_activity_at || updated_at
+    [last_activity_at, last_repository_updated_at, updated_at].compact.max
   end
 
   def project_id

changelogs/unreleased/sh-dashboard-sort-fix.yml

+---
+title: Fix project dashboard showing the wrong timestamps
+merge_request:
+author:
+type: fixed

spec/features/dashboard/projects_spec.rb

@@ -37,6 +37,14 @@ feature 'Dashboard Projects' do
 
       expect(page).to have_xpath("//time[@datetime='#{project.last_repository_updated_at.getutc.iso8601}']")
     end
+
+    it 'shows the last_activity_at attribute as the update date' do
+      project.update_attributes!(last_repository_updated_at: 1.hour.ago, last_activity_at: Time.now)
+
+      visit dashboard_projects_path
+
+      expect(page).to have_xpath("//time[@datetime='#{project.last_activity_at.getutc.iso8601}']")
+    end
   end
 
   context 'when last_repository_updated_at and last_activity_at are missing' do

spec/models/project_spec.rb

@@ -517,6 +517,20 @@ describe Project do
       it 'returns the project\'s last update date if it has no events' do
         expect(project.last_activity_date).to eq(project.updated_at)
       end
+
+      it 'returns the most recent timestamp' do
+        project.update_attributes(updated_at: nil,
+                                  last_activity_at: timestamp,
+                                  last_repository_updated_at: timestamp - 1.hour)
+
+        expect(project.last_activity_date).to eq(timestamp)
+
+        project.update_attributes(updated_at: timestamp,
+                                  last_activity_at: timestamp - 1.hour,
+                                  last_repository_updated_at: nil)
+
+        expect(project.last_activity_date).to eq(timestamp)
+      end
     end
   end