sqlite3 as the default database, but you can generate a new rails application with a database of your choice. Just add the
-d option followed by the name of the database.
$ rails new MyApp -T -d postgresql
This is a (non-exhaustive) list of available database options:
The -T command indicate to skip the installation of minitest. To install an alternative test suite like RSpec, edit the Gemfile and add
group :development, :test do gem 'rspec-rails', end
Then launch the following command from the console:
rails generate rspec:install