Add registrant verification versions table according to existing logic

Creates a log_registrant_verifications table and version class as per https://github.com/internetee/registry/issues/1425#issuecomment-567117002

app/models/registrant_verification.rb

@@ -1,7 +1,7 @@
 # Used in Registrant portal to collect registrant verifications
 # Registrant postgres user can access this table directly.
 class RegistrantVerification < ApplicationRecord
-  has_paper_trail
+  has_paper_trail class_name: 'RegistrantVerificationVersion'
 
   # actions
   CONFIRMED = 'confirmed'

app/models/version/registrant_verification_version.rb

@@ -0,0 +1,7 @@
+class RegistrantVerificationVersion < PaperTrail::Version
+  include VersionSession
+  self.table_name    = :log_registrant_verifications
+  self.sequence_name = :log_registrant_verifications_id_seq
+
+  scope :deleted, -> { where(event: 'destroy') }
+end

db/migrate/20191227110904_add_json_based_version_to_registrant_verifications.rb

@@ -0,0 +1,24 @@
+class AddJsonBasedVersionToRegistrantVerifications < ActiveRecord::Migration[5.0]
+  def change
+    name = 'registrant_verification'
+    table_name = "log_#{name.tableize}"
+
+    create_table table_name do |t|
+      t.string   :item_type, null: false
+      t.integer  :item_id,   null: false
+      t.string   :event,     null: false
+      t.string   :whodunnit
+      t.json     :object
+      t.json     :object_changes
+      t.datetime :created_at
+      t.string :session
+    end
+    add_index table_name, [:item_type, :item_id]
+    add_index table_name, :whodunnit
+
+    add_column name.tableize, :creator_id_tmp, :integer
+    add_column name.tableize, :updater_id_tmp, :integer
+    rename_column name.tableize, :creator_id_tmp, :creator_id
+    rename_column name.tableize, :updater_id_tmp, :updater_id
+  end
+end

test/fixtures/registrant_verifications.yml

@@ -3,5 +3,4 @@ one:
   action_type: domain_delete
   created_at: <%= Time.zone.parse('2010-07-05') %>
   domain: shop
-  domain_name: shop.test
   verification_token: 1234

test/models/registrant_verification_test.rb

@@ -5,7 +5,7 @@ class RegistrantVerificationTest < ActiveSupport::TestCase
     registrant_verification = registrant_verifications(:one)
     random_action = "random#{rand(100)}"
 
-    assert_difference -> { PaperTrail::Version.count } do
+    assert_difference -> { RegistrantVerificationVersion.count } do
       registrant_verification.update_attributes!(action: random_action)
     end
   end