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db | ||
examples | ||
features | ||
lib | ||
spec | ||
.gitignore | ||
.rbenv-version | ||
.rspec | ||
.rvmrc | ||
.travis.yml | ||
Gemfile | ||
Gemfile.lock | ||
Guardfile | ||
History.txt | ||
LICENSE | ||
README.markdown | ||
Rakefile | ||
TODO | ||
VERSION.yml | ||
cucumber.yml | ||
database_cleaner.gemspec |
README.markdown
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, 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 |
Sequel | Yes | Yes | No |
Driver | Truncation | Transaction | Deletion |
---|---|---|---|
Mongo | 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.
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 proceess 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) 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 uncommited 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 the the scope of this README but here is a good SO answer on this topic for Postgres.
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 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
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
Additional ActiveRecord options for Truncation
The following options are available for ActiveRecord's :truncation
strategy only for MySQL and Postgres.
:pre_count
- When set totrue
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?):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 totrue
.
RSpec Example
RSpec.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
Minitest Example
DatabaseCleaner.strategy = :transaction
class MiniTest::Spec
before :each do
DatabaseCleaner.start
end
after :each do
DatabaseCleaner.clean
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:
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
Before do
DatabaseCleaner.start
end
After do |scenario|
DatabaseCleaner.clean
end
This should cover the basics of tear down between scenarios and keeping your database clean.
For more examples see the section "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.
#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}] |
Couch Potato | DatabaseCleaner[:couch_potato] |
Multiple connections not yet supported |
Sequel | DatabaseCleaner[:sequel] |
? |
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 same 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:
# 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:
client_min_messages = warning
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
:
DatabaseCleaner.logger = Rails.logger
COPYRIGHT
Copyright (c) 2009 Ben Mabey. See LICENSE for details.