title: Database Cleaner not working in minitest rails
body: <p>My Minitest controller tests are working fine if I run them alone using <code>rake minitest:controllers</code> but when I run <code>rake minitest:all</code> then I get validation failed error. It is because email is already used in model tests. I used DatabaseCleaner to clean the database but unable to clean database.</p>
  
  <p>My code for database cleaner: </p>
  
  <pre><code>require "database_cleaner"
  DatabaseCleaner.strategy = :transaction
  
  class MiniTest::Rails::ActionController::TestCase
      include Devise::TestHelpers
  
      def setup
        DatabaseCleaner.start
      end
  
      def teardown
        DatabaseCleaner.clean
      end
  </code></pre>