database_cleaner/README.textile

h1. 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.

ActiveRecord, DataMapper, MongoMapper, Mongoid, and CouchPotato are supported.

Here is an overview of the strategies supported for each library:

|_. ORM        |_.  Truncation  |_.  Transaction  |_.  Deletion    |
| ActiveRecord | Yes            | **Yes**         | Yes            |
| DataMapper   | Yes            | **Yes**         | No             |
| CouchPotato  | **Yes**        | No              | No             |
| MongoMapper  | **Yes**        | No              | No             |
| Mongoid      | **Yes**        | No              | No             |

(Default strategy for each library is denoted in bold)

The ActiveRecord @:deletion@ strategy is only useful for when the @:truncation@ strategy causes
locks (as reported by some Oracle DB users).  The @:truncation@ strategy is the preferred option
since it is much faster.

Database Cleaner also includes a @null@ strategy (that does no cleaning at all) which can be used 
with any ORM library. You can also explicitly use it by setting your strategy to @nil@.

h2. How to use

<pre>
  require 'database_cleaner'
  DatabaseCleaner.strategy = :truncation

  # then, whenever you need to clean the DB
  DatabaseCleaner.clean
</pre>

With the :truncation strategy you can also pass in options, for example:
<pre>
  DatabaseCleaner.strategy = :truncation, {:only => %w[widgets dogs some_other_table]}
</pre>

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

(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:

<pre>
  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
</pre>

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:

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

Example usage with RSpec:

<pre>
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
</pre>

For use in Cucumber please see the section below.

In rare cases DatabaseCleaner will encounter errors that it will log.  By default it uses STDOUT set to the ERROR level but you can configure this to use whatever Logger you desire.  Here's an example of using the Rails.logger in env.rb:

<pre>
  DatabaseCleaner.logger = Rails.logger
</pre>


h2. How to use with multiple ORM's

Sometimes you need to use multiple ORMs in your application. You can use DatabaseCleaner to clean multiple ORMs, and multiple connections for those ORMs.

<pre>
  #How to specify particular orms
  DatabaseCleaner[:active_record].strategy = :transaction
  DatabaseCleaner[:mongo_mapper].strategy = :truncation
  
  #How to specify particular connections
  DatabaseCleaner[:active_record,{:connection => :two}]
</pre>

Usage beyond that remains the same with DatabaseCleaner.start calling any setup on the different configured connections, and DatabaseCleaner.clean executing afterwards.

Configuration options


|_. ORM         |_.   How to access               |_.   Notes                                                                |
| Active Record | DatabaseCleaner[:active_record] | Connection specified as :symbol keys, loaded from config/database.yml    |
| Data Mapper   | DatabaseCleaner[:data_mapper]   | Connection specified as :symbol keys, loaded via Datamapper repositories |
| Mongo Mapper  | DatabaseCleaner[:mongo_mapper]  | Multiple connections not yet supported                                   |
| Mongoid       | DatabaseCleaner[:mongoid]       | Multiple connections not yet supported                                   |
| Couch Potato  | DatabaseCleaner[:couch_potato]  | Multiple connections not yet supported                                   |

h2. 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:

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

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:

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

You can have the best of both worlds and use the best one for the job:
<pre>
  #env.rb
  require 'database_cleaner'
  require 'database_cleaner/cucumber'
  DatabaseCleaner.strategy = (ENV['SELENIUM'] == 'true') ? :truncation : :transaction
</pre>

h2. COPYRIGHT

Copyright (c) 2009 Ben Mabey. See LICENSE for details.