Why would rails not reset the test database between runs

Question

There are comments in the rails codebase that indicate that the test database should be reset between runs

rake -T

rake test:all                           # Run tests quickly by merging all types and not resetting db
rake test:all:db                        # Run tests quickly, but also reset db

config/database.yml

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:

This doesn''t seem to be the case for me.

I'm using factory girl generate test models, here is an example factory

FactoryGirl.define do
  factory :podcast do
    sequence(:title)     { |n| "Podcast #{n}" }
    sequence(:feed_url)  { |n| "http://podcast.com/#{n}" }
  end
end

The podcast should have a unique feed_url so I validate it's uniqueness in the model.

class Podcast < ActiveRecord::Base
  validates :feed_url, uniqueness: true, presence: true
end

In test_helper.rb I lint all factories

ENV["RAILS_ENV"] ||= "test"
require File.expand_path('../../config/environment', __FILE__)
require 'rails/test_help'
require 'minitest/autorun'

FactoryGirl.lint

My test creates a podcast, builds another with the same name, then asserts that the second is invalid.

require 'test_helper'

describe Podcast do
  describe '#feed_url' do
    it 'must be unique' do
      podcast = create(:podcast)
      new_podcast = build(:podcast, feed_url: podcast.name)

      assert_invalid podcast, :feed_url, 'has already been taken'
    end
  end
end

The first time I run the tests it executes without errors and the tests all pass. The second time I run the tests the Factory Girl lint fails because podcast feed_url has already been taken.

Why isn't the test database being rebuilt between runs?

Answer 1

We have a more involved FactoryGirl set up that prepares our database with some canonical items, but I think you could probably put this code directly in your test_helper.rb to assure the database is emptied:

# Destroy all models because they do not get destroyed automatically
(ActiveRecord::Base.connection.tables - %w{schema_migrations}).each do |table_name|
  ActiveRecord::Base.connection.execute "TRUNCATE TABLE #{table_name};"
end

Alternatively, run rake db:test:prepare before every run.

There is a gem too that you can use, but I don't have any experience with it: http://rubygems.org/gems/database_cleaner.