[Dmails] Fix senders copy being created when validations fail

app/models/dmail.rb

@@ -39,6 +39,7 @@ class Dmail < ApplicationRecord
           copy = Dmail.new(params)
           copy.owner_id = copy.to_id
           copy.save unless copy.to_id == copy.from_id
+          raise ActiveRecord::Rollback if copy.errors.any?
 
           # sender's copy
           copy = Dmail.new(params)

test/unit/dmail_test.rb

@@ -77,6 +77,18 @@ class DmailTest < ActiveSupport::TestCase
       end
     end
 
+    should "not create a senders copy when validations fail" do
+      Danbooru.config.stubs(:disable_throttles?).returns(false)
+      @user = create(:user, created_at: 2.weeks.ago)
+      @recipient = create(:user)
+      as(@user) do
+        (Danbooru.config.dmail_minute_limit + 1).times do
+          Dmail.create_split(attributes_for(:dmail, from_id: @user.id, to_id: @recipient.id))
+        end
+      end
+      assert_equal(Danbooru.config.dmail_minute_limit * 2, Dmail.count)
+    end
+
     should "should parse user names" do
       dmail = build(:dmail, owner: @user)
       dmail.to_id = nil