feat(dunning): Allow soft deletion on dunning campaign

app/models/dunning_campaign.rb

@@ -2,6 +2,8 @@
 
 class DunningCampaign < ApplicationRecord
   include PaperTrailTraceable
+  include Discard::Model
+  self.discard_column = :deleted_at
 
   ORDERS = %w[name code].freeze
 
@@ -15,8 +17,9 @@ class DunningCampaign < ApplicationRecord
   validates :name, presence: true
   validates :days_between_attempts, numericality: {greater_than: 0}
   validates :max_attempts, numericality: {greater_than: 0}
-  validates :code, uniqueness: {scope: :organization_id}
+  validates :code, uniqueness: {scope: :organization_id}, unless: :deleted_at
 
+  default_scope -> { kept }
   scope :applied_to_organization, -> { where(applied_to_organization: true) }
   scope :with_currency_threshold, ->(currencies) {
     joins(:thresholds)
@@ -37,6 +40,7 @@ def self.ransackable_attributes(_auth_object = nil)
 #  applied_to_organization :boolean          default(FALSE), not null
 #  code                    :string           not null
 #  days_between_attempts   :integer          default(1), not null
+#  deleted_at              :datetime
 #  description             :text
 #  max_attempts            :integer          default(1), not null
 #  name                    :string           not null
@@ -46,8 +50,9 @@ def self.ransackable_attributes(_auth_object = nil)
 #
 # Indexes
 #
+#  index_dunning_campaigns_on_deleted_at                  (deleted_at)
 #  index_dunning_campaigns_on_organization_id             (organization_id)
-#  index_dunning_campaigns_on_organization_id_and_code    (organization_id,code) UNIQUE
+#  index_dunning_campaigns_on_organization_id_and_code    (organization_id,code) UNIQUE WHERE (deleted_at IS NULL)
 #  index_unique_applied_to_organization_per_organization  (organization_id) UNIQUE WHERE (applied_to_organization = true)
 #
 # Foreign Keys

db/migrate/20241120085057_add_deleted_at_to_dunning_campaigns.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class AddDeletedAtToDunningCampaigns < ActiveRecord::Migration[7.1]
+  def change
+    add_column :dunning_campaigns, :deleted_at, :timestamp
+
+    safety_assured do
+      add_index :dunning_campaigns, :deleted_at
+    end
+  end
+end

db/migrate/20241120090305_update_unique_index_on_dunning_campaigns.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class UpdateUniqueIndexOnDunningCampaigns < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def change
+    remove_index :dunning_campaigns, %i[organization_id code], unique: true, algorithm: :concurrently
+
+    add_index :dunning_campaigns,
+      [:organization_id, :code],
+      unique: true,
+      where: "deleted_at IS NULL",
+      algorithm: :concurrently
+  end
+end

spec/models/dunning_campaign_spec.rb

@@ -17,4 +17,32 @@
   it { is_expected.to validate_numericality_of(:max_attempts).is_greater_than(0) }
 
   it { is_expected.to validate_uniqueness_of(:code).scoped_to(:organization_id) }
+
+  describe "code validation" do
+    let(:code) { "123456" }
+    let(:organization) { create(:organization) }
+
+    it "validates uniqueness of code scoped to organization_id excluding deleted records" do
+      create(:dunning_campaign, code:, organization:)
+      new_record = build(:dunning_campaign, code:, organization:)
+
+      expect(new_record).not_to be_valid
+      expect(new_record.errors[:code]).to include("value_already_exist")
+
+      # Records with deleted_at set should not conflict
+      deleted_record = create(:dunning_campaign, :deleted, code:, organization:)
+      expect(deleted_record).to be_valid
+    end
+  end
+
+  describe "default scope" do
+    let(:deleted_dunning_campaign) { create(:dunning_campaign, :deleted) }
+
+    before { deleted_dunning_campaign }
+
+    it "only returns non-deleted dunning_campaign objects" do
+      expect(described_class.all).to eq([])
+      expect(described_class.with_discarded).to eq([deleted_dunning_campaign])
+    end
+  end
 end