Database Cleaner

Database Cleaner is a set of strategies for cleaning your database in Ruby. The original use case was to ensure a clean state during tests. Each strategy is a small amount of code but is code that is usually needed in any ruby app that is testing with a database.

Right now the only ORM supported is ActiveRecord and it currently has two strategies: truncation and transaction.

Support for DataMapper is built-in. All that needs to be written are the strategies. :)

How to use

  require 'database_cleaner'
  DatabaseCleaner.strategy = :truncation

  # then, whenever you need to clean the DB
  DatabaseCleaner.clean

With the :truncation strategy you can also pass in options, for example:

  DatabaseCleaner.strategy = :truncation, {:only => %w[widgets dogs some_other_table]}

  DatabaseCleaner.strategy = :truncation, {:except => %w[widgets]}

(I should point out the truncation strategy will never truncate your schema_migrations table.)

Some strategies require that you call DatabaseCleaner.start before calling clean (for example the :transaction one needs to know to open up a transaction). So you would have:

  require 'database_cleaner'
  DatabaseCleaner.strategy = :transaction
  
  DatabaseCleaner.start # usually this is called in setup of a test
  dirty_the_db
  DatabaseCleaner.clean # cleanup of the test

At times you may want to do a single clean with one strategy. For example, you may want to start the process by truncating all the tables, but then use the faster transaction strategy the remaining time. To accomplish this you can say:

  require 'database_cleaner'
  DatabaseCleaner.clean_with :truncation
  DatabaseCleaner.strategy = :transaction
  # then make the DatabaseCleaner.start and DatabaseCleaner.clean calls appropriately

Example usage with RSpec:

Spec::Runner.configure do |config|

  config.before(:suite) do
    DatabaseCleaner.strategy = :transaction
    DatabaseCleaner.clean_with(:truncation)
  end

  config.before(:each) do
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end

end

For use in Cucumber please see the section below.

Why?

One of my motivations for writing this library was to have an easy way to turn on what Rails calls “transactional_fixtures” in my non-rails ActiveRecord projects. For example, Cucumber ships with a Rails world that will wrap each scenario in a transaction. This is great, but what if you are using ActiveRecord in a non-rails project? You used to have to copy-and-paste the needed code, but with DatabaseCleaner you can now say:

  #env.rb
  require 'database_cleaner'
  require 'database_cleaner/cucumber'
  DatabaseCleaner.strategy = :transaction

Now lets say you are running your features and it requires that another process be involved (i.e. Selenium running against your app’s server.) You can simply change your strategy type:

  #env.rb
  require 'database_cleaner'
  require 'database_cleaner/cucumber'
  DatabaseCleaner.strategy = :truncation

You can have the best of both worlds and use the best one for the job:

  #env.rb
  require ‘database_cleaner’
  require ‘database_cleaner/cucumber’
  DatabaseCleaner.strategy = (<span class="caps">ENV</span>[‘<span class="caps">SELENIUM</span>’] == ‘true’) ? :truncation : :transaction

COPYRIGHT

Copyright © 2009 Ben Mabey. See LICENSE for details.