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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:

  • How to set up your machine for Rails development
  • How to run specific groups of unit tests from the Rails test suite
  • How the ActiveRecord portion of the Rails test suite operates

The Easy Way

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

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.

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.

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

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 libxml2 and libxslt together with their development files for Nokogiri. In Ubuntu that's

$ sudo apt-get install libxml2 libxml2-dev libxslt1-dev

If you are on Fedora or CentOS, you can run

$ sudo yum install libxml2 libxml2-devel libxslt libxslt-devel

If you are running Arch Linux, you're done with:

$ sudo pacman -S libxml2 libxslt

If you have any problems with these libraries, you can install them manually by compiling the source code. Just follow the instructions at the Red Hat/CentOS section of the Nokogiri tutorials .

Also, SQLite3 and its development files for the sqlite3 gem — 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

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. With dependencies 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 any single test separately too:

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

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.

WARNING: 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.

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.

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. 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

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';

and create the test databases:

$ cd activerecord
$ bundle exec rake mysql:build_databases

PostgreSQL's authentication works differently. A simple way to set up the development environment for example is to run with your development account

$ sudo -u postgres createuser --superuser $USER

and then create the test databases with

$ cd activerecord
$ bundle exec rake postgresql:build_databases

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

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

NOTE: 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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