Add specs for credits behaviour

app/services/credit_notes/create_from_progressive_billing_invoice.rb

@@ -12,6 +12,7 @@ def initialize(progressive_billing_invoice:, amount:, reason: :other)
 
     def call
       return result unless amount.positive?
+      return result.forbidden_failure! unless progressive_billing_invoice.progressive_billing?
 
       # Important to call this method as it modifies @amount if needed
       items = calculate_items!
@@ -34,7 +35,7 @@ def calculate_items!
       remaining = amount
 
       # The amount can be greater than a single fee amount. We'll keep on deducting until we've credited enough
-      progressive_billing_invoice.fees.each do |fee|
+      progressive_billing_invoice.fees.order(amount_cents: :desc).each do |fee|
         # no further credit remaining
         break if remaining.zero?
 
@@ -49,7 +50,7 @@ def calculate_items!
       end
 
       # it could be that we have some amount remaining
-      # TODO: verify and check in v2
+      # TODO(ProgressiveBilling): verify and check in v2
       if remaining.positive?
         @amount -= remaining
       end

spec/services/credit_notes/create_from_progressive_billing_invoice_spec.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe CreditNotes::CreateFromProgressiveBillingInvoice, type: :service do
+  subject(:credit_service) { described_class.new(progressive_billing_invoice:, amount:, reason:) }
+
+  let(:reason) { :other }
+  let(:amount) { 0 }
+  let(:invoice_type) { :progressive_billing }
+  let(:customer) { create(:customer) }
+  let(:organization) { customer.organization }
+
+  let(:progressive_billing_invoice) do
+    create(
+      :invoice,
+      customer:,
+      organization:,
+      currency: 'EUR',
+      fees_amount_cents: 120,
+      total_amount_cents: 120,
+      invoice_type:
+    )
+  end
+
+  let(:fee1) do
+    create(
+      :fee,
+      invoice: progressive_billing_invoice,
+      amount_cents: 80
+    )
+  end
+
+  let(:fee2) do
+    create(
+      :fee,
+      invoice: progressive_billing_invoice,
+      amount_cents: 40
+    )
+  end
+
+  before do
+    progressive_billing_invoice
+    fee1
+    fee2
+  end
+
+  describe "#call" do
+    it "does nothing when amount is zero" do
+      expect { credit_service.call }.not_to change(CreditNote, :count)
+    end
+
+    context "with amount greater than zero" do
+      let(:amount) { 100 }
+
+      context 'when called with a subscription invoice' do
+        let(:invoice_type) { :subscription }
+
+        it "fails when the passed in invoice is not a progressive billing invoice" do
+          result = credit_service.call
+          expect(result).not_to be_success
+        end
+      end
+
+      it "creates a credit note for all required fees" do
+        result = credit_service.call
+        credit_note = result.credit_note
+
+        expect(credit_note.credit_amount_cents).to eq(amount)
+        expect(credit_note.items.size).to eq(2)
+
+        credit_fee1 = credit_note.items.find { |i| i.fee == fee1 }
+        expect(credit_fee1.amount_cents).to eq(80)
+        credit_fee2 = credit_note.items.find { |i| i.fee == fee2 }
+        expect(credit_fee2.amount_cents).to eq(20)
+      end
+    end
+  end
+end

spec/services/credits/progressive_billing_service_spec.rb

@@ -175,7 +175,7 @@
     end
 
     describe "#call" do
-      it "applies one credit to the invoice" do
+      it "applies all the credits to the invoice" do
         result = credit_service.call
         expect(result.credits.size).to eq(2)
         first_credit = result.credits.find { |credit| credit.progressive_billing_invoice == progressive_billing_invoice }
@@ -185,7 +185,20 @@
         expect(first_credit.amount_cents).to eq(980)
 
         expect(invoice.progressive_billing_credit_amount_cents).to eq(1000)
-        # todo: validate that we've created a credit note here
+      end
+
+      it "creates credit notes for the remainder of the progressive billed invoices" do
+        expect { credit_service.call }.to change(CreditNote, :count).by(2)
+        # we were able to credit 1000 from the invoice, this means we've got 20 and 200 remaining respectively
+        aggregate_failures do
+          expect(progressive_billing_invoice2.credit_notes.size).to eq(1)
+          expect(progressive_billing_invoice3.credit_notes.size).to eq(1)
+
+          first = progressive_billing_invoice2.credit_notes.sole
+          expect(first.credit_amount_cents).to eq(20)
+          last = progressive_billing_invoice3.credit_notes.sole
+          expect(last.credit_amount_cents).to eq(200)
+        end
       end
     end
   end

spec/spec_helper.rb

@@ -2,6 +2,13 @@
 
 require 'webmock/rspec'
 
+# Allow remote debugging when RUBY_DEBUG_PORT is set
+if ENV['RUBY_DEBUG_PORT']
+  require 'debug/open_nonstop'
+else
+  require 'debug'
+end
+
 RSpec.configure do |config|
   config.expect_with :rspec do |expectations|
     expectations.include_chain_clauses_in_custom_matcher_descriptions = true