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Development Dependencies Install

This guide covers how to setup an environment for Ruby on Rails core development.

After reading this guide, you will know:

1 The Easy Way

The easiest and recommended way to get a development environment ready to hack is to use the Rails development box.

2 The Hard Way

In case you can't use the Rails development box, see section above, these are the steps to manually build a development box for Ruby on Rails core development.

2.1 Install Git

Ruby on Rails uses Git for source code control. The Git homepage has installation instructions. There are a variety of resources on the net that will help you get familiar with Git:

  • Try Git course is an interactive course that will teach you the basics.
  • The official Documentation is pretty comprehensive and also contains some videos with the basics of Git
  • Everyday Git will teach you just enough about Git to get by.
  • The PeepCode screencast on Git is easier to follow.
  • GitHub offers links to a variety of Git resources.
  • Pro Git is an entire book about Git with a Creative Commons license.

2.2 Clone the Ruby on Rails Repository

Navigate to the folder where you want the Ruby on Rails source code (it will create its own rails subdirectory) and run:

$ git clone git://
$ cd rails

2.3 Set up and Run the Tests

The test suite must pass with any submitted code. No matter whether you are writing a new patch, or evaluating someone else's, you need to be able to run the tests.

Install first SQLite3 and its development files for the sqlite3 gem. Mac OS X users are done with:

$ brew install sqlite3

In Ubuntu you're done with just:

$ sudo apt-get install sqlite3 libsqlite3-dev

And if you are on Fedora or CentOS, you're done with

$ sudo yum install sqlite3 sqlite3-devel

If you are on Arch Linux, you will need to run:

$ sudo pacman -S sqlite

For FreeBSD users, you're done with:

# pkg install sqlite3

Or compile the databases/sqlite3 port.

Get a recent version of Bundler

$ gem install bundler
$ gem update bundler

and run:

$ bundle install --without db

This command will install all dependencies except the MySQL and PostgreSQL Ruby drivers. We will come back to these soon.

If you would like to run the tests that use memcached, you need to ensure that you have it installed and running.

You can use Homebrew to install memcached on OS X:

$ brew install memcached

On Ubuntu you can install it with apt-get:

$ sudo apt-get install memcached

Or use yum on Fedora or CentOS:

$ sudo yum install memcached

If you are running on Arch Linux:

$ sudo pacman -S memcached

For FreeBSD users, you're done with:

# pkg install memcached

Alternatively, you can compile the databases/memcached port.

With the dependencies now installed, you can run the test suite with:

$ bundle exec rake test

You can also run tests for a specific component, like Action Pack, by going into its directory and executing the same command:

$ cd actionpack
$ bundle exec rake test

If you want to run the tests located in a specific directory use the TEST_DIR environment variable. For example, this will run the tests in the railties/test/generators directory only:

$ cd railties
$ TEST_DIR=generators bundle exec rake test

You can run the tests for a particular file by using:

$ cd actionpack
$ bundle exec ruby -Itest test/template/form_helper_test.rb

Or, you can run a single test in a particular file:

$ cd actionpack
$ bundle exec ruby -Itest path/to/test.rb -n test_name

2.4 Active Record Setup

The test suite of Active Record attempts to run four times: once for SQLite3, once for each of the two MySQL gems (mysql and mysql2), and once for PostgreSQL. We are going to see now how to set up the environment for them.

If you're working with Active Record code, you must ensure that the tests pass for at least MySQL, PostgreSQL, and SQLite3. Subtle differences between the various adapters have been behind the rejection of many patches that looked OK when tested only against MySQL.

2.4.1 Database Configuration

The Active Record test suite requires a custom config file: activerecord/test/config.yml. An example is provided in activerecord/test/config.example.yml which can be copied and used as needed for your environment.

2.4.2 MySQL and PostgreSQL

To be able to run the suite for MySQL and PostgreSQL we need their gems. Install first the servers, their client libraries, and their development files.

On OS X, you can run:

$ brew install mysql
$ brew install postgresql

Follow the instructions given by Homebrew to start these.

In Ubuntu just run:

$ sudo apt-get install mysql-server libmysqlclient15-dev
$ sudo apt-get install postgresql postgresql-client postgresql-contrib libpq-dev

On Fedora or CentOS, just run:

$ sudo yum install mysql-server mysql-devel
$ sudo yum install postgresql-server postgresql-devel

If you are running Arch Linux, MySQL isn't supported anymore so you will need to use MariaDB instead (see this announcement):

$ sudo pacman -S mariadb libmariadbclient mariadb-clients
$ sudo pacman -S postgresql postgresql-libs

FreeBSD users will have to run the following:

# pkg install mysql56-client mysql56-server
# pkg install postgresql93-client postgresql93-server

Or install them through ports (they are located under the databases folder). If you run into troubles during the installation of MySQL, please see the MySQL documentation.

After that, run:

$ rm .bundle/config
$ bundle install

First, we need to delete .bundle/config because Bundler remembers in that file that we didn't want to install the "db" group (alternatively you can edit the file).

In order to be able to run the test suite against MySQL you need to create a user named rails with privileges on the test databases:

$ mysql -uroot -p

mysql> CREATE USER 'rails'@'localhost';
mysql> GRANT ALL PRIVILEGES ON activerecord_unittest.*
       to 'rails'@'localhost';
mysql> GRANT ALL PRIVILEGES ON activerecord_unittest2.*
       to 'rails'@'localhost';
mysql> GRANT ALL PRIVILEGES ON inexistent_activerecord_unittest.*
       to 'rails'@'localhost';

and create the test databases:

$ cd activerecord
$ bundle exec rake db:mysql:build

PostgreSQL's authentication works differently. To setup the development environment with your development account, on Linux or BSD, you just have to run:

$ sudo -u postgres createuser --superuser $USER

and for OS X:

$ createuser --superuser $USER

Then you need to create the test databases with

$ cd activerecord
$ bundle exec rake db:postgresql:build

It is possible to build databases for both PostgreSQL and MySQL with

$ cd activerecord
$ bundle exec rake db:create

You can cleanup the databases using

$ cd activerecord
$ bundle exec rake db:drop

Using the rake task to create the test databases ensures they have the correct character set and collation.

You'll see the following warning (or localized warning) during activating HStore extension in PostgreSQL 9.1.x or earlier: "WARNING: => is deprecated as an operator".

If you're using another database, check the file activerecord/test/config.yml or activerecord/test/config.example.yml for default connection information. You can edit activerecord/test/config.yml to provide different credentials on your machine if you must, but obviously you should not push any such changes back to Rails.


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Please contribute if you see any typos or factual errors. To get started, you can read our documentation contributions section.

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If for whatever reason you spot something to fix but cannot patch it yourself, please open an issue.

And last but not least, any kind of discussion regarding Ruby on Rails documentation is very welcome in the rubyonrails-docs mailing list.