ActiveRecord::Base.transaction do
  User.find(1).update(name: 'User 1 - Modified')
  begin
    ActiveRecord::Base.transaction do
      User.find(5).update!(name: 'User 5 - Modified')
      raise FinError::Blah.new('blah')
    end
  rescue FinError::Blah => e
    puts "Error occurred"
  end
end
puts User.find(1).name
# Expected behavior is that User 1's name will change but User 5's name change will be rolled back
puts User.find(5).name

# Outputs:
# Error occurred
# User 1 - Modified
# User 5 - Modified