Upgrade tests using checkRequirements

<?php

/**
 * Upgrade test for the bare database..
 *
 * Load an empty installation of Drupal 7 and run the upgrade process on it.
 */
class BareUpgradePathTestCase extends UpgradePathTestCase {
  public static function getInfo() {
    return array(
      'name'  => 'Bare upgrade test',
      'description'  => 'Bare upgrade test.',
      'group' => 'Upgrade path',
    );
  }

  public function checkRequirements() {
    if (!function_exists('gzopen')) {
      return array(
        'errors' => array(
          t('The zlib extension is not enabled. As a result, this test cannot run.'),
        ),
      );
    }
    return parent::checkRequirements();
  }

  public function setUp() {
    // Path to the database dump.
    $this->databaseDumpFiles = array(
      drupal_get_path('module', 'simpletest') . '/tests/upgrade/drupal-7.bare.database.php.gz',
    );
    parent::setUp();
  }

  /**
   * Test a successful upgrade.
   */
  public function testBareUpgrade() {
    $this->assertTrue($this->performUpgrade(), t('The upgrade was completed successfully.'));
  }
}