assign auction type for nil value rake task

lib/tasks/assing_auction_platform_type.rake

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+namespace :auction do
+  desc 'Check closed disputes with expired_at in the Past'
+  task assign_platform_type: :environment do
+    auctions = Auction.where(platform: nil)
+
+    auctions.each do |auction|
+      auction.update(platform: :auto)
+    end
+  end
+end

test/tasks/assign_auction_platform_type_test.rb

@@ -0,0 +1,27 @@
+require 'test_helper'
+
+class AssignAuctionPlatformTypeTest < ActiveSupport::TestCase
+  setup do
+    @auction_one = auctions(:one)
+    @auction_two = auctions(:idn)
+  end
+
+  def test_output
+    assert_nil @auction_one.platform
+    assert_nil @auction_two.platform
+
+    run_task
+
+    @auction_one.reload
+    @auction_two.reload
+
+    assert_equal @auction_one.platform, "auto"
+    assert_equal @auction_two.platform, "auto"
+  end
+
+  private
+
+  def run_task
+    Rake::Task['auction:assign_platform_type'].execute
+  end
+end