Single-Table Inheritance with attribute on sub-class, raises after becomes sub-class #47538

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", ">= 7.0.4.2"
  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 :vehicles, force: true do |t|
    t.string :type
    t.string :name
  end
end

class Vehicle < ActiveRecord::Base
end

class Car < Vehicle
  # virtual attribute
  attribute :virtual_string, :string
end

class BugTest < Minitest::Test
  # without `becomes`, works fine
  def test_virtual_attribute
    car = Car.create!
    car.virtual_string = "my value"
    assert_equal car.virtual_string, "my value"
  end

  # FAILS
  def test_virtual_attribute_after_becomes
    became_car = Vehicle.new.becomes(Car)

    became_car.virtual_string = "my value"
    # RAISES
    # ActiveModel::MissingAttributeError: can't write unknown attribute `virtual_string`

    assert_equal car.virtual_string, "my value"
  end
end