```ruby
require 'spec_helper'
require 'action_controller'
require 'generator_spec/test_case'
require 'generators/double_entry/install/install_generator'


describe DoubleEntry::Generators::InstallGenerator do
  include GeneratorSpec::TestCase

  destination File.expand_path("/tmp", __FILE__)

  before do
    prepare_destination
    run_generator
  end

  specify do
    expect(destination_root).to have_structure {
      directory "db" do
        directory "migrate" do
          migration "create_double_entry_tables" do
            contains 'class CreateDoubleEntryTable'
            contains 'create_table "double_entry_account_balances"'
            contains 'create_table "double_entry_lines"'
            contains 'create_table "double_entry_line_aggregates"'
            contains 'create_table "double_entry_line_checks"'
          end
        end
      end
    }
  end

end
```

Use a local tmp dir
user
```ruby
require 'spec_helper'
require 'action_controller'
require 'generator_spec/test_case'
require 'generators/double_entry/install/install_generator'


describe DoubleEntry::Generators::InstallGenerator do
  include GeneratorSpec::TestCase

  destination File.expand_path("../../../../../tmp", __FILE__)

  before do
    prepare_destination
    run_generator
  end

  specify do
    expect(destination_root).to have_structure {
      directory "db" do
        directory "migrate" do
          migration "create_double_entry_tables" do
            contains 'class CreateDoubleEntryTable'
            contains 'create_table "double_entry_account_balances"'
            contains 'create_table "double_entry_lines"'
            contains 'create_table "double_entry_line_aggregates"'
            contains 'create_table "double_entry_line_checks"'
          end
        end
      end
    }
  end

end
```
assistant