Sometimes `create_association` does not delete existing records

[willnet]

Steps to reproduce

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  # Activate the gem you are reporting the issue against.
  gem "activerecord", "~> 7.0.0"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"
require "logger"

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
  end

  create_table :addresses, force: true do |t|
    t.references :user
  end
end

class User < ActiveRecord::Base
  has_one :address, -> { order(id: :desc) }, dependent: :destroy
end

class Address < ActiveRecord::Base
  belongs_to :user
end

class BugTest < Minitest::Test
  def test_association_stuff
    user = User.create!
    Address.create(user: user)
    assert_equal 1, Address.count
    user.create_address!
    assert_equal 1, Address.count # fail
  end
end

-> { order(id: :desc) } in the reproduction code is written to reproduce 100%. Some environments may reproduce it without this argument.

The create_association method may load a record for deletion after INSERT, and if a newly created record is loaded at that time, the DELETE statement will not be issued and multiple records will exist.

Expected behavior

user.create_address! remove old address record.

Actual behavior

user.create_address! doesn't remove old address record.

System configuration

Rails version: 7.0.4.2
Ruby version: 3.2.1

This PR already fixed the bug. So this problem does not occur on the main branch.

It would be great if someone could backport #46386 to the 7-0-stable branch.

[willnet]

sorry, it was already backported to the 7-0-stable branch

Backport create_association fix to 7-0-stable by casperisfine · Pull Request #46799 · rails/rails