# 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, Sequel, MongoMapper, Mongoid, CouchPotato, Ohm and Redis are supported. [![Build Status](https://secure.travis-ci.org/bmabey/database_cleaner.png)](http://travis-ci.org/bmabey/database_cleaner) 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
Sequel Yes Yes No
Redis Yes No No
Ohm Yes No No
Driver Truncation Transaction Deletion
Mongo Yes No No
Moped Yes No No
(Default strategy for each library is denoted in bold) 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`. For support or to discuss development please use the [Google Group](http://groups.google.com/group/database_cleaner). ## What strategy is fastest? For the SQL libraries the fastest option will be to use `:transaction` as transactions are simply rolled back. If you can use this strategy you should. However, if you wind up needing to use multiple database connections in your tests (i.e. your tests run in a different process than your application) then using this strategy becomes a bit more difficult. You can get around the problem a number of ways. One common approach is to force all processes to use the same database connection ([common ActiveRecord hack](http://blog.plataformatec.com.br/2011/12/three-tips-to-improve-the-performance-of-your-test-suite/)) however this approach has been reported to result in non-deterministic failures. Another approach is to have the transactions rolled back in the application's process and relax the isolation level of the database (so the tests can read the uncommitted transactions). An easier, but slower, solution is to use the `:truncation` or `:deletion` strategy. So what is fastest out of `:deletion` and `:truncation`? Well, it depends on your table structure and what percentage of tables you populate in an average test. The reasoning is out of the scope of this README but here is a [good SO answer on this topic for Postgres](http://stackoverflow.com/questions/11419536/postgresql-truncation-speed/11423886#11423886). Some people report much faster speeds with `:deletion` while others say `:truncation` is faster for them. The best approach therefore is it try all options on your test suite and see what is faster. If you are using ActiveRecord then take a look at the [additional options](#additional-activerecord-options-for-truncation) available for `:truncation`. ## Dependencies Because database_cleaner supports multiple ORMs, it doesn't make sense to include all the dependencies for each one in the gemspec. However, the DataMapper adapter does depend on dm-transactions. Therefore, if you use DataMapper, you must include dm-transactions in your Gemfile/bundle/gemset manually. ## How to use ```ruby 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: ```ruby DatabaseCleaner.strategy = :truncation, {:only => %w[widgets dogs some_other_table]} ``` ```ruby DatabaseCleaner.strategy = :truncation, {:except => %w[widgets]} ``` With Ohm and Redis, `:only` and `:except` take a list of strings to be passed to [`keys`](http://redis.io/commands/keys)). (I should point out the truncation strategy will never truncate your schema_migrations table.) Some strategies need to be started before tests are run (for example the `:transaction` strategy needs to know to open up a transaction). This can be accomplished by calling `DatabaseCleaner.start` at the beginning of the run, or by running the tests inside a block to `Database.cleaning`. So you would have: ```ruby 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 # OR DatabaseCleaner.cleaning do dirty_the_db end ``` 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: ```ruby require 'database_cleaner' DatabaseCleaner.clean_with :truncation DatabaseCleaner.strategy = :transaction # then make the DatabaseCleaner.start and DatabaseCleaner.clean calls appropriately ``` ### Additional ActiveRecord options for Truncation The following options are available for ActiveRecord's `:truncation` strategy _only_ for MySQL and Postgres. * `:pre_count` - When set to `true` this will check each table for existing rows before truncating it. This can speed up test suites when many of the tables to be truncated are never populated. Defaults to `:false`. (Also, see the section on [What strategy is fastest?](#what-strategy-is-fastest)) * `:reset_ids` - This only matters when `:pre_count` is used, and it will make sure that a tables auto-incrementing id is reset even if there are no rows in the table (e.g. records were created in the test but also removed before DatabaseCleaner gets to it). Defaults to `true`. The following option is available for ActiveRecord's `:truncation` and `:deletion` strategy for any DB. * `:cache_tables` - When set to `true` the list of tables to truncate or delete from will only be read from the DB once, otherwise it will be read before each cleanup run. Set this to `false` if you create and drop tables in your tests. Defaults to `true`. ### RSpec Example ```ruby RSpec.configure do |config| config.before(:suite) do DatabaseCleaner.strategy = :transaction DatabaseCleaner.clean_with(:truncation) end config.around(:each) do |example| DatabaseCleaner.cleaning do example.run end end end ``` ### Minitest Example ```ruby DatabaseCleaner.strategy = :transaction class MiniTest::Spec before :each do DatabaseCleaner.start end after :each do DatabaseCleaner.clean end end # with the minitest-around gem, this may be used instead: class Minitest::Spec around do |tests| DatabaseCleaner.cleaning(&tests) end end ``` ### Cucumber Example If you're using Cucumber with Rails, just use the generator that ships with cucumber-rails, and that will create all the code you need to integrate DatabaseCleaner into your Rails project. Otherwise, to add DatabaseCleaner to your project by hand, create a file `features/support/database_cleaner.rb` that looks like this: ```ruby begin require 'database_cleaner' require 'database_cleaner/cucumber' DatabaseCleaner.strategy = :truncation rescue NameError raise "You need to add database_cleaner to your Gemfile (in the :test group) if you wish to use it." end Around do |scenario, block| DatabaseCleaner.cleaning(&block) end ``` This should cover the basics of tear down between scenarios and keeping your database clean. For more examples see the section ["Why?"](#why). ## 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. ```ruby #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}] # You may also pass in the model directly: DatabaseCleaner[:active_record,{:model => ModelWithDifferentConnection}] ``` 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. You may also pass in the ActiveRecord model under the :model key.
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 databases supported for Mongoid 3. Specify DatabaseCleaner[:mongoid, {:connection => :db_name}]
Moped DatabaseCleaner[:moped] It is necessary to configure database name with DatabaseCleaner[:moped].db = db_name otherwise name `default` will be used.
Couch Potato DatabaseCleaner[:couch_potato] Multiple connections not yet supported
Sequel DatabaseCleaner[:sequel] Multiple databases supported; specify DatabaseCleaner[:sequel, {:connection => Sequel.connect(uri)}]
Redis DatabaseCleaner[:redis] Connection specified as Redis URI
Ohm DatabaseCleaner[:ohm] Connection specified as Redis URI
## 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. After copying and pasting code to do this several times I decided to package it up as a gem and save everyone a bit of time. ## Common Errors #### DatabaseCleaner is trying to use the wrong ORM DatabaseCleaner has an autodetect mechanism where if you do not explicitly define your ORM it will use the first ORM it can detect that is loaded. Since ActiveRecord is the most common ORM used that is the first one checked for. Sometimes other libraries (e.g. ActiveAdmin) will load other ORMs (e.g. ActiveRecord) even though you are using a different ORM. This will result in DatabaseCleaner trying to use the wrong ORM (e.g. ActiveRecord) unless you explicitly define your ORM like so: ```ruby # How to setup your ORM explicitly DatabaseCleaner[:mongoid].strategy = :truncation ``` ### STDERR is being flooded when using Postgres If you are using Postgres and have foreign key constraints, the truncation strategy will cause a lot of extra noise to appear on STDERR (in the form of "NOTICE truncate cascades" messages). To silence these warnings set the following log level in your `postgresql.conf` file: ```ruby client_min_messages = warning ``` For ActiveRecord, you add the following parameter in your database.yml file: 
test:
  adapter: postgresql
  # ...
  min_messages: WARNING
### Nothing happens in JRuby with Sequel using transactions Due to an inconsistency in JRuby's implementation of Fibers, Sequel gives a different connection to `DatabaseCleaner.start` than is used for tests run between `.start` and `.clean`. This can be worked around by running your tests in a block like `DatabaseCleaner.cleaning { run_my_tests }` instead, which does not use Fibers. ## Debugging 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`: ```ruby DatabaseCleaner.logger = Rails.logger ``` ## COPYRIGHT Copyright (c) 2009 Ben Mabey. See LICENSE for details.