Troubleshoot BrowserTestBase and Composer Manager so that modern automated tests can be written

[aweingarten]

Business Requirements

• As a contributor to the cloudflare module I want to be able to write automated tests using the best frameworks provided by Drupal Core.

Technical Requirements

• Submit a core patch for BrowserTestBase so that it will bootstrap the correct autoloader for Drupal.
  BrowserTestBase assumes that the autoloader is in docroot/core/vendor however composer manager moves this to docroot/vendor. This seems to cause problems.

Background Error

Drupal\cloudflare\Tests\CloudFlareConfigSettingsTest::testGoTo PHPUnit_Framework_Exception: PHP Fatal error: Cannot redeclare composerRequireDrupal8() (previously declared in /var/www/docroot/vendor/composer/autoload_real.php:56) in /var/www/docroot/core/vendor/composer/autoload_real.php on line 59 Fatal error: Cannot redeclare composerRequireDrupal8() (previously declared in /var/www/docroot/vendor/composer/autoload_real.php:56) in /var/www/docroot/core/vendor/composer/autoload_real.php on line 59