Create task that destroys removed activities

app/jobs/remove_activities_job.rb

@@ -0,0 +1,42 @@
+class RemoveActivitiesJob < ApplicationJob
+  # permanently remove activities that match all of the following criteria:
+  # - status is 'removed'
+  # - updated_at is more than 1 month ago
+  # - one of the following is true:
+  #   - draft is true (never published)
+  #   - series_memberships is empty and less then 25 submissions and latest submission is more than 1 month ago
+  #
+  # Destroy is called on each activity individually to ensure that callbacks are run
+  # This means the activity will be removed from any series, evaluations it is a member of
+  # and any submissions will be removed
+  queue_as :cron
+
+  def perform
+    ContentPage.where(status: 'removed').where('updated_at < ?', 1.month.ago).find_each do |activity|
+      if activity.draft? || activity.series_memberships.empty?
+        # destroy series memberships first explicitly, as they are dependent: :restrict_with_error
+        activity.series_memberships.destroy_all
+
+        activity.destroy
+      end
+    end
+
+    Exercise.where(status: 'removed').where('updated_at < ?', 1.month.ago).find_each do |activity|
+      if activity.draft? ||
+         (activity.series_memberships.empty? &&
+           (activity.submissions.empty? ||
+             (activity.submissions.count < 25 && activity.submissions.reorder(:created_at).last.created_at < 1.month.ago)))
+        # destroy submissions first explicitly, as they are dependent: :restrict_with_error
+        activity.submissions.destroy_all
+
+        # destroy series memberships first explicitly, as they are dependent: :restrict_with_error
+        activity.series_memberships.destroy_all
+
+        activity.destroy
+      end
+    end
+
+    # rerun this job in 1 month
+    RemoveActivitiesJob.set(wait: 1.month).perform_later
+  end
+end

config/deploy/production.rb

@@ -13,7 +13,7 @@
 set :delayed_job_pools_per_server,
     'dodona' => {
       'default,statistics,exports,cleaning' => 2,
-      'git' => 1,
+      'git,cron' => 1,
     },
     'sisyphus' => {
       'submissions,low_priority_submissions,high_priority_submissions' => 6

test/jobs/remove_activities_job_test.rb

@@ -0,0 +1,105 @@
+require 'test_helper'
+
+class RemoveActivitiesJobTest < ActiveJob::TestCase
+  test 'should remove "removed" draft activities' do
+    c = create :content_page
+    create :activity_read_state, activity: c
+    c.update status: :removed, draft: true, updated_at: 2.months.ago
+    e = create :exercise
+    create :submission, exercise: e
+    e.update status: :removed, draft: true, updated_at: 2.months.ago
+    s = create :series
+    s.activities << c
+    s.activities << e
+
+    assert_difference 'ContentPage.count', -1 do
+      assert_difference 'Exercise.count', -1 do
+        RemoveActivitiesJob.perform_now
+      end
+    end
+  end
+
+  test 'should remove "removed" activities with no series memberships and no submissions' do
+    create :content_page, status: :removed, draft: false, updated_at: 2.months.ago
+    create :exercise, status: :removed, draft: false, updated_at: 2.months.ago
+
+    assert_difference 'ContentPage.count', -1 do
+      assert_difference 'Exercise.count', -1 do
+        RemoveActivitiesJob.perform_now
+      end
+    end
+  end
+
+  test 'should not remove "removed" activities with series memberships' do
+    c = create :content_page, status: :removed, draft: false, updated_at: 2.months.ago
+    e = create :exercise, status: :removed, draft: false, updated_at: 2.months.ago
+    s = create :series
+    s.activities << c
+    s.activities << e
+
+    assert_no_difference 'ContentPage.count' do
+      assert_no_difference 'Exercise.count' do
+        RemoveActivitiesJob.perform_now
+      end
+    end
+  end
+
+  test 'should not remove "removed" activities with more than 25 submissions' do
+    e = create :exercise, status: :removed, draft: false, updated_at: 2.months.ago
+    create_list :submission, 26, exercise: e
+
+    assert_no_difference 'Exercise.count' do
+      RemoveActivitiesJob.perform_now
+    end
+  end
+
+  test 'should remove "removed" activities with less than 25 submissions and last submission more than 1 month ago' do
+    e = create :exercise, status: :removed, draft: false, updated_at: 2.months.ago
+    create_list :submission, 21, exercise: e, created_at: 2.months.ago
+
+    assert_difference 'Submission.count', -21 do
+      assert_difference 'Exercise.count', -1 do
+        RemoveActivitiesJob.perform_now
+      end
+    end
+  end
+
+  test 'should not remove "removed" activities with less than 25 submissions and last submission less than 1 month ago' do
+    e = create :exercise, status: :removed, draft: false, updated_at: 2.months.ago
+    create_list :submission, 5, exercise: e, created_at: 2.months.ago
+    create_list :submission, 3, exercise: e, created_at: 2.weeks.ago
+
+    assert_no_difference 'Submission.count' do
+      assert_no_difference 'Exercise.count' do
+        RemoveActivitiesJob.perform_now
+      end
+    end
+  end
+
+  test 'should not removed non removed activities' do
+    create :exercise, updated_at: 2.months.ago
+    create :content_page, updated_at: 2.months.ago
+    create :exercise, draft: true, updated_at: 2.months.ago
+    create :content_page, draft: true, updated_at: 2.months.ago
+
+    assert_no_difference 'Exercise.count' do
+      assert_no_difference 'ContentPage.count' do
+        RemoveActivitiesJob.perform_now
+      end
+    end
+  end
+
+  test 'should not remove activities updated less than 1 month ago' do
+    create :exercise, status: :removed, draft: true, updated_at: 2.weeks.ago
+
+    assert_no_difference 'Exercise.count' do
+      RemoveActivitiesJob.perform_now
+    end
+  end
+
+  test 'should reschedule itself' do
+    assert_enqueued_with(job: RemoveActivitiesJob) do
+      RemoveActivitiesJob.perform_now
+    end
+  end
+end