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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 Active Record 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 the steps below 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.
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 https://github.com/rails/rails.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 SQLite3 and its development files for the sqlite3 gem. On macOS users are done with:

$ brew install sqlite3

In Ubuntu you're done with just:

$ sudo apt-get install sqlite3 libsqlite3-dev

If you are on Fedora or CentOS, you're done with

$ sudo yum install libsqlite3x libsqlite3x-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.

NOTE: 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 macOS:

$ 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

Railties Setup

Some Railties tests depend on a JavaScript runtime environment, such as having Node.js installed.

Active Record Setup

Active Record's test suite runs three times: once for SQLite3, once for MySQL, 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.

On macOS, you can run:

$ brew install mysql
$ brew install postgresql

Follow the instructions given by Homebrew to start these.

On Ubuntu, just run:

$ sudo apt-get install mysql-server libmysqlclient-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 postgresql94-client postgresql94-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 macOS:

$ 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

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.

Action Cable Setup

Action Cable uses Redis as its default subscriptions adapter (read more). Thus, in order to have Action Cable's tests passing you need to install and have Redis running.

Install Redis From Source

Redis' documentation discourage installations with package managers as those are usually outdated. Installing from source and bringing the server up is straight forward and well documented on Redis' documentation.

Install Redis From Package Manager

On macOS, you can run:

$ brew install redis

Follow the instructions given by Homebrew to start these.

On Ubuntu, just run:

$ sudo apt-get install redis-server

On Fedora or CentOS (requires EPEL enabled), just run:

$ sudo yum install redis

If you are running Arch Linux, just run:

$ sudo pacman -S redis
$ sudo systemctl start redis

FreeBSD users will have to run the following:

# portmaster databases/redis

Active Storage Setup

When working on Active Storage, it is important to note that you need to install its JavaScript dependencies while working on that section of the codebase. In order to install these dependencies, it is necessary to have Yarn, a Node.js package manager, available on your system. A prerequisite for installing this package manager is that Node.js is installed.

On macOS, you can run:

brew install yarn

On Ubuntu, you can run:

curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list

sudo apt-get update && sudo apt-get install yarn

On Fedora or CentOS, just run:

sudo wget https://dl.yarnpkg.com/rpm/yarn.repo -O /etc/yum.repos.d/yarn.repo

sudo yum install yarn

Finally, after installing Yarn, you will need to run the following command inside of the activestorage directory to install the dependencies:

yarn install