Add abstract model Key

app/models/key.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class Key < ApplicationRecord
+  self.abstract_class = true
+end

app/models/rsa_key.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class RSAKey < ApplicationRecord
+class RSAKey < Key
   PRIVATE_KEY_CLEAR_DELAY = 12.hours.freeze
 
   attr_accessor :private_key_pem, :private_key_pem_secret

spec/models/key_spec.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Key do
+  pending "add some examples to (or delete) #{__FILE__}"
+end