Add new payment method ApiCustomerCredit

It was previously modelled by a "Check" payment method

app/models/spree/payment_method/api_customer_credit.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+# This payment method is not intended to be used with payment, it's used with customer account
+# transaction to indicate the transaction was created via API.
+module Spree
+  class PaymentMethod
+    class ApiCustomerCredit < Spree::PaymentMethod
+      # Name and description are translatable string, to allow instances to customise them
+      def name
+        "api_payment_method.name"
+      end
+
+      def description
+        "api_payment_method.description"
+      end
+
+      def payment_source_class
+        nil
+      end
+
+      def method_type
+        "check" # empty view
+      end
+
+      def source_required?
+        false
+      end
+    end
+  end
+end

spec/factories/payment_method_factory.rb

@@ -34,4 +34,9 @@ FactoryBot.define do
     environment { 'test' }
     internal { true }
   end
+
+  factory :api_customer_credit_payment_method, class: Spree::PaymentMethod::ApiCustomerCredit do
+    environment { 'test' }
+    internal { true }
+  end
 end

spec/models/spree/payment_method/api_customer_credit_spec.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe Spree::PaymentMethod::ApiCustomerCredit do
+  subject { build(:api_customer_credit_payment_method) }
+
+  describe "#name" do
+    it { expect(subject.name).to eq("api_payment_method.name") }
+  end
+
+  describe "#description" do
+    it { expect(subject.description).to eq("api_payment_method.description") }
+  end
+end