Implement un-setting the deletion date & add tests

app/models/user_cleaner.rb

@@ -5,7 +5,7 @@ class UserCleaner
   # Returns all users who have been inactive for 6 months,
   # i.e. their last sign-in date is more than 6 months ago.
   def inactive_users
-    User.where("last_sign_in_at < ?", 6.months.ago)
+    User.where("last_sign_in_at < ?", 6.months.ago.to_date)
   end
 
   # Sets the deletion date for inactive users.
@@ -18,6 +18,25 @@ def set_deletion_date_for_inactive_users
     end
   end
 
+  # Unsets the deletion date for users who have been active recently.
+  #
+  # This method finds all users whose deletion date is set and unsets it if the
+  # user has been active in the last 6 months.
+  #
+  # Note that this method just serves as a safety measure. The deletion date
+  # should be unset after every successful user sign-in, see the Warden callback
+  # in `config/initializers/after_sign_in.rb`. If for some reason the callback
+  # does not work, this method will prevent active users from being deleted
+  # as a last resort.
+  def unset_deletion_date_for_recently_active_users
+    User.where.not(deletion_date: nil).find_each do |user|
+      # Note that technically, 40 days is the maximum possible value here,
+      # if our intended flow works as expected. We use 6 months to be on the
+      # safe side as we do not want to delete active users.
+      user.update(deletion_date: nil) if user.last_sign_in_at >= 6.months.ago.to_date
+    end
+  end
+
   # Deletes all users whose deletion date is in the past.
   #
   # The deletion date must have been set beforehand by calling
@@ -33,8 +52,9 @@ def delete_users_according_to_deletion_date
     puts "#{deleted_count} stale users deleted."
   end
 
-  def handle_inactive_users
+  def handle_inactive_users!
     set_deletion_date_for_inactive_users
+    unset_deletion_date_for_recently_active_users
     delete_users_according_to_deletion_date
   end
 end

spec/models/user_cleaner_spec.rb

@@ -13,6 +13,29 @@
     expect(active_user.deletion_date).to be_nil
   end
 
+  it "unassigns a deletion date from recently active users" do
+    deletion_date = Date.current + 5.days
+    user_inactive = FactoryBot.create(:user, deletion_date: deletion_date,
+                                             last_sign_in_at: 7.months.ago)
+    user_inactive2 = FactoryBot.create(:user, deletion_date: deletion_date,
+                                              last_sign_in_at: 6.months.ago - 1.day)
+    user_active = FactoryBot.create(:user, deletion_date: deletion_date,
+                                           last_sign_in_at: 6.months.ago)
+    user_active_recently = FactoryBot.create(:user, deletion_date: deletion_date,
+                                                    last_sign_in_at: 2.days.ago)
+
+    UserCleaner.new.unset_deletion_date_for_recently_active_users
+    user_inactive.reload
+    user_inactive2.reload
+    user_active.reload
+    user_active_recently.reload
+
+    expect(user_inactive.deletion_date).to eq(deletion_date)
+    expect(user_inactive2.deletion_date).to eq(deletion_date)
+    expect(user_active.deletion_date).to be_nil
+    expect(user_active_recently.deletion_date).to be_nil
+  end
+
   it "deletes users with a deletion date in the past or present" do
     user_past1 = FactoryBot.create(:user, deletion_date: Date.current - 1.day)
     user_past2 = FactoryBot.create(:user, deletion_date: Date.current - 1.year)