A Reproduction Script for Rails issue #28718

28718.rb

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"
  gem "rails", "5.0.2"
  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 :users do |t|
    t.string :first_name
    t.string :last_name
  end
end

class User < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_frozen_attributes
    user = User.new(first_name: 'Alex', last_name: 'Kosh')
    refute user.first_name.frozen?

    x = User.new(user.attributes)
    x.inspect

    refute user.first_name.frozen?


    refute user.first_name.frozen?
  end

  def test_mutated_name
    first_name = "Alex_Capitalized"
    user = User.new(first_name: first_name)
    first_name.downcase!

    assert_equal "Alex_Capitalized", user.first_name
    assert_equal "#<User id: nil, first_name: \"Alex_Capitalized\", last_name: nil>", user.inspect
  end
end