drupal_web_test_case.php

<?php
// $Id$

/**
 * Base class for Drupal tests.
 *
 * Do not extend this class, use one of the subclasses in this file.
 */
abstract class DrupalTestCase {
  /**
   * The test run ID.
   *
   * @var string
   */
  protected $testId;

  /**
   * The original database prefix, before it was changed for testing purposes.
   *
   * @var string
   */
  protected $originalPrefix = NULL;

  /**
   * The original file directory, before it was changed for testing purposes.
   *
   * @var string
   */
  protected $originalFileDirectory = NULL;

  /**
   * Time limit for the test.
   */
  protected $timeLimit = 500;

  /**
   * Current results of this test case.
   *
   * @var Array
   */
  public $results = array(
    '#pass' => 0,
    '#fail' => 0,
    '#exception' => 0,
    '#debug' => 0,
  );

  /**
   * Assertions thrown in that test case.
   *
   * @var Array
   */
  protected $assertions = array();

  /**
   * This class is skipped when looking for the source of an assertion.
   *
   * When displaying which function an assert comes from, it's not too useful
   * to see "drupalWebTestCase->drupalLogin()', we would like to see the test
   * that called it. So we need to skip the classes defining these helper
   * methods.
   */
  protected $skipClasses = array(__CLASS__ => TRUE);

  /**
   * Constructor for DrupalWebTestCase.
   *
   * @param $test_id
   *   Tests with the same id are reported together.
   */
  public function __construct($test_id = NULL) {
    $this->testId = $test_id;
  }

  /**
   * Internal helper: stores the assert.
   *
   * @param $status
   *   Can be 'pass', 'fail', 'exception'.
   *   TRUE is a synonym for 'pass', FALSE for 'fail'.
   * @param $message
   *   The message string.
   * @param $group
   *   Which group this assert belongs to.
   * @param $caller
   *   By default, the assert comes from a function whose name starts with
   *   'test'. Instead, you can specify where this assert originates from
   *   by passing in an associative array as $caller. Key 'file' is
   *   the name of the source file, 'line' is the line number and 'function'
   *   is the caller function itself.
   */
  protected function assert($status, $message = '', $group = 'Other', array $caller = NULL) {
    global $db_prefix;

    // Convert boolean status to string status.
    if (is_bool($status)) {
      $status = $status ? 'pass' : 'fail';
    }

    // Increment summary result counter.
    $this->results['#' . $status]++;

    // Get the function information about the call to the assertion method.
    if (!$caller) {
      $caller = $this->getAssertionCall();
    }

    // Switch to non-testing database to store results in.
    $current_db_prefix = $db_prefix;
    $db_prefix = $this->originalPrefix;

    // Creation assertion array that can be displayed while tests are running.
    $this->assertions[] = $assertion = array(
      'test_id' => $this->testId,
      'test_class' => get_class($this),
      'status' => $status,
      'message' => $message,
      'message_group' => $group,
      'function' => $caller['function'],
      'line' => $caller['line'],
      'file' => $caller['file'],
    );

    // Store assertion for display after the test has completed.
    db_insert('simpletest')
      ->fields($assertion)
      ->execute();

    // Return to testing prefix.
    $db_prefix = $current_db_prefix;
    // We do not use a ternary operator here to allow a breakpoint on
    // test failure.
    if ($status == 'pass') {
      return TRUE;
    }
    else {
      return FALSE;
    }
  }

  /**
   * Store an assertion from outside the testing context.
   *
   * This is useful for inserting assertions that can only be recorded after
   * the test case has been destroyed, such as PHP fatal errors. The caller
   * information is not automatically gathered since the caller is most likely
   * inserting the assertion on behalf of other code. In all other respects
   * the method behaves just like DrupalTestCase::assert() in terms of storing
   * the assertion.
   *
   * @return
   *   Message ID of the stored assertion.
   *
   * @see DrupalTestCase::assert()
   * @see DrupalTestCase::deleteAssert()
   */
  public static function insertAssert($test_id, $test_class, $status, $message = '', $group = 'Other', array $caller = array()) {
    // Convert boolean status to string status.
    if (is_bool($status)) {
      $status = $status ? 'pass' : 'fail';
    }

    $caller += array(
      'function' => t('Unknown'),
      'line' => 0,
      'file' => t('Unknown'),
    );

    $assertion = array(
      'test_id' => $test_id,
      'test_class' => $test_class,
      'status' => $status,
      'message' => $message,
      'message_group' => $group,
      'function' => $caller['function'],
      'line' => $caller['line'],
      'file' => $caller['file'],
    );

    return db_insert('simpletest')
      ->fields($assertion)
      ->execute();
  }

  /**
   * Delete an assertion record by message ID.
   *
   * @param $message_id
   *   Message ID of the assertion to delete.
   * @return
   *   TRUE if the assertion was deleted, FALSE otherwise.
   *
   * @see DrupalTestCase::insertAssert()
   */
  public static function deleteAssert($message_id) {
    return (bool) db_delete('simpletest')
      ->condition('message_id', $message_id)
      ->execute();
  }

  /**
   * Cycles through backtrace until the first non-assertion method is found.
   *
   * @return
   *   Array representing the true caller.
   */
  protected function getAssertionCall() {
    $backtrace = debug_backtrace();

    // The first element is the call. The second element is the caller.
    // We skip calls that occurred in one of the methods of our base classes
    // or in an assertion function.
   while (($caller = $backtrace[1]) &&
         ((isset($caller['class']) && isset($this->skipClasses[$caller['class']])) ||
           substr($caller['function'], 0, 6) == 'assert')) {
      // We remove that call.
      array_shift($backtrace);
    }

    return _drupal_get_last_caller($backtrace);
  }

  /**
   * Check to see if a value is not false (not an empty string, 0, NULL, or FALSE).
   *
   * @param $value
   *   The value on which the assertion is to be done.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertTrue($value, $message = '', $group = 'Other') {
    return $this->assert((bool) $value, $message ? $message : t('Value @value is TRUE.', array('@value' => var_export($value, TRUE))), $group);
  }

  /**
   * Check to see if a value is false (an empty string, 0, NULL, or FALSE).
   *
   * @param $value
   *   The value on which the assertion is to be done.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertFalse($value, $message = '', $group = 'Other') {
    return $this->assert(!$value, $message ? $message : t('Value @value is FALSE.', array('@value' => var_export($value, TRUE))), $group);
  }

  /**
   * Check to see if a value is NULL.
   *
   * @param $value
   *   The value on which the assertion is to be done.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertNull($value, $message = '', $group = 'Other') {
    return $this->assert(!isset($value), $message ? $message : t('Value @value is NULL.', array('@value' => var_export($value, TRUE))), $group);
  }

  /**
   * Check to see if a value is not NULL.
   *
   * @param $value
   *   The value on which the assertion is to be done.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertNotNull($value, $message = '', $group = 'Other') {
    return $this->assert(isset($value), $message ? $message : t('Value @value is not NULL.', array('@value' => var_export($value, TRUE))), $group);
  }

  /**
   * Check to see if two values are equal.
   *
   * @param $first
   *   The first value to check.
   * @param $second
   *   The second value to check.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertEqual($first, $second, $message = '', $group = 'Other') {
    return $this->assert($first == $second, $message ? $message : t('Value @first is equal to value @second.', array('@first' => var_export($first, TRUE), '@second' => var_export($second, TRUE))), $group);
  }

  /**
   * Check to see if two values are not equal.
   *
   * @param $first
   *   The first value to check.
   * @param $second
   *   The second value to check.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertNotEqual($first, $second, $message = '', $group = 'Other') {
    return $this->assert($first != $second, $message ? $message : t('Value @first is not equal to value @second.', array('@first' => var_export($first, TRUE), '@second' => var_export($second, TRUE))), $group);
  }

  /**
   * Check to see if two values are identical.
   *
   * @param $first
   *   The first value to check.
   * @param $second
   *   The second value to check.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertIdentical($first, $second, $message = '', $group = 'Other') {
    return $this->assert($first === $second, $message ? $message : t('Value @first is identical to value @second.', array('@first' => var_export($first, TRUE), '@second' => var_export($second, TRUE))), $group);
  }

  /**
   * Check to see if two values are not identical.
   *
   * @param $first
   *   The first value to check.
   * @param $second
   *   The second value to check.
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE if the assertion succeeded, FALSE otherwise.
   */
  protected function assertNotIdentical($first, $second, $message = '', $group = 'Other') {
    return $this->assert($first !== $second, $message ? $message : t('Value @first is not identical to value @second.', array('@first' => var_export($first, TRUE), '@second' => var_export($second, TRUE))), $group);
  }

  /**
   * Fire an assertion that is always positive.
   *
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   TRUE.
   */
  protected function pass($message = NULL, $group = 'Other') {
    return $this->assert(TRUE, $message, $group);
  }

  /**
   * Fire an assertion that is always negative.
   *
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @return
   *   FALSE.
   */
  protected function fail($message = NULL, $group = 'Other') {
    return $this->assert(FALSE, $message, $group);
  }

  /**
   * Fire an error assertion.
   *
   * @param $message
   *   The message to display along with the assertion.
   * @param $group
   *   The type of assertion - examples are "Browser", "PHP".
   * @param $caller
   *   The caller of the error.
   * @return
   *   FALSE.
   */
  protected function error($message = '', $group = 'Other', array $caller = NULL) {
    if ($group == 'User notice') {
      // Since 'User notice' is set by trigger_error() which is used for debug
      // set the message to a status of 'debug'.
      return $this->assert('debug', $message, 'Debug', $caller);
    }

    return $this->assert('exception', $message, $group, $caller);
  }

  /**
   * Run all tests in this class.
   */
  public function run() {
    // Initialize verbose debugging.
    simpletest_verbose(NULL, file_directory_path(), get_class($this));

    // HTTP auth settings (<username>:<password>) for the simpletest browser
    // when sending requests to the test site.
    $this->httpauth_method = variable_get('simpletest_httpauth_method', CURLAUTH_BASIC);
    $username = variable_get('simpletest_httpauth_username', NULL);
    $password = variable_get('simpletest_httpauth_password', NULL);
    if ($username && $password) {
      $this->httpauth_credentials = $username . ':' . $password;
    }

    set_error_handler(array($this, 'errorHandler'));
    $class = get_class($this);
    // Iterate through all the methods in this class.
    foreach (get_class_methods($class) as $method) {
      // If the current method starts with "test", run it - it's a test.
      if (strtolower(substr($method, 0, 4)) == 'test') {
        // Insert a fail record. This will be deleted on completion to ensure
        // that testing completed.
        $method_info = new ReflectionMethod($class, $method);
        $caller = array(
          'file' => $method_info->getFileName(),
          'line' => $method_info->getStartLine(),
          'function' => $class . '->' . $method . '()',
        );
        $completion_check_id = DrupalTestCase::insertAssert($this->testId, $class, FALSE, t('The test did not complete due to a fatal error.'), 'Completion check', $caller);
        $this->setUp();
        try {
          $this->$method();
          // Finish up.
        }
        catch (Exception $e) {
          $this->exceptionHandler($e);
        }
        $this->tearDown();
        // Remove the completion check record.
        DrupalTestCase::deleteAssert($completion_check_id);
      }
    }
    // Clear out the error messages and restore error handler.
    drupal_get_messages();
    restore_error_handler();
  }

  /**
   * Handle errors during test runs.
   *
   * Because this is registered in set_error_handler(), it has to be public.
   * @see set_error_handler
   */
  public function errorHandler($severity, $message, $file = NULL, $line = NULL) {
    if ($severity & error_reporting()) {
      $error_map = array(
        E_STRICT => 'Run-time notice',
        E_WARNING => 'Warning',
        E_NOTICE => 'Notice',
        E_CORE_ERROR => 'Core error',
        E_CORE_WARNING => 'Core warning',
        E_USER_ERROR => 'User error',
        E_USER_WARNING => 'User warning',
        E_USER_NOTICE => 'User notice',
        E_RECOVERABLE_ERROR => 'Recoverable error',
      );

      $backtrace = debug_backtrace();
      $this->error($message, $error_map[$severity], _drupal_get_last_caller($backtrace));
    }
    return TRUE;
  }

  /**
   * Handle exceptions.
   *
   * @see set_exception_handler
   */
  protected function exceptionHandler($exception) {
    $backtrace = $exception->getTrace();
    // Push on top of the backtrace the call that generated the exception.
    array_unshift($backtrace, array(
      'line' => $exception->getLine(),
      'file' => $exception->getFile(),
    ));
    require_once DRUPAL_ROOT . '/includes/errors.inc';
    $this->error(t('%type: %message in %function (line %line of %file).', _drupal_decode_exception($exception)), 'Uncaught exception', _drupal_get_last_caller($backtrace));
  }

  /**
   * Generates a random string of ASCII characters of codes 32 to 126.
   *
   * The generated string includes alpha-numeric characters and common misc
   * characters. Use this method when testing general input where the content
   * is not restricted.
   *
   * @param $length
   *   Length of random string to generate.
   * @return
   *   Randomly generated string.
   */
  public static function randomString($length = 8) {
    $str = '';
    for ($i = 0; $i < $length; $i++) {
      $str .= chr(mt_rand(32, 126));
    }
    return $str;
  }

  /**
   * Generates a random string containing letters and numbers.
   *
   * The string will always start with a letter. The letters may be upper or
   * lower case. This method is better for restricted inputs that do not
   * accept certain characters. For example, when testing input fields that
   * require machine readable values (i.e. without spaces and non-standard
   * characters) this method is best.
   *
   * @param $length
   *   Length of random string to generate.
   * @return
   *   Randomly generated string.
   */
  public static function randomName($length = 8) {
    $values = array_merge(range(65, 90), range(97, 122), range(48, 57));
    $max = count($values) - 1;
    $str = chr(mt_rand(97, 122));
    for ($i = 1; $i < $length; $i++) {
      $str .= chr($values[mt_rand(0, $max)]);
    }
    return $str;
  }
}

/**
 * Test case for Drupal unit tests.
 *
 * These tests can not access the database nor files. Calling any Drupal
 * function that needs the database will throw exceptions. These include
 * watchdog(), module_implements(), module_invoke_all() etc.
 */
class DrupalUnitTestCase extends DrupalTestCase {

  /**
   * Constructor for DrupalUnitTestCase.
   */
  function __construct($test_id = NULL) {
    parent::__construct($test_id);
    $this->skipClasses[__CLASS__] = TRUE;
  }

  protected function setUp() {
    global $db_prefix, $conf;

    // Store necessary current values before switching to prefixed database.
    $this->originalPrefix = $db_prefix;
    $this->originalFileDirectory = file_directory_path();

    spl_autoload_register('db_autoload');

    // Reset all statics so that test is performed with a clean environment.
    drupal_static_reset();

    // Generate temporary prefixed database to ensure that tests have a clean starting point.
    $db_prefix = Database::getConnection()->prefixTables('{simpletest' . mt_rand(1000, 1000000) . '}');
    $conf['file_public_path'] = $this->originalFileDirectory . '/' . $db_prefix;

    // If locale is enabled then t() will try to access the database and
    // subsequently will fail as the database is not accessible.
    $module_list = module_list();
    if (isset($module_list['locale'])) {
      $this->originalModuleList = $module_list;
      unset($module_list['locale']);
      module_list(TRUE, FALSE, FALSE, $module_list);
    }
  }

  protected function tearDown() {
    global $db_prefix, $conf;
    if (preg_match('/simpletest\d+/', $db_prefix)) {
      $conf['file_public_path'] = $this->originalFileDirectory;
      // Return the database prefix to the original.
      $db_prefix = $this->originalPrefix;
      // Restore modules if necessary.
      if (isset($this->originalModuleList)) {
        module_list(TRUE, FALSE, FALSE, $this->originalModuleList);
      }
    }
  }
}

/**
 * Test case for typical Drupal tests.
 */
class DrupalWebTestCase extends DrupalTestCase {
  /**
   * The URL currently loaded in the internal browser.
   *
   * @var string
   */
  protected $url;

  /**
   * The handle of the current cURL connection.
   *
   * @var resource
   */
  protected $curlHandle;

  /**
   * The headers of the page currently loaded in the internal browser.
   *
   * @var Array
   */
  protected $headers;

  /**
   * The content of the page currently loaded in the internal browser.
   *
   * @var string
   */
  protected $content;

  /**
   * The content of the page currently loaded in the internal browser (plain text version).
   *
   * @var string
   */
  protected $plainTextContent;

  /**
   * The parsed version of the page.
   *
   * @var SimpleXMLElement
   */
  protected $elements = NULL;

  /**
   * The current user logged in using the internal browser.
   *
   * @var bool
   */
  protected $loggedInUser = FALSE;

  /**
   * The current cookie file used by cURL.
   *
   * We do not reuse the cookies in further runs, so we do not need a file
   * but we still need cookie handling, so we set the jar to NULL.
   */
  protected $cookieFile = NULL;

  /**
   * Additional cURL options.
   *
   * DrupalWebTestCase itself never sets this but always obeys what is set.
   */
  protected $additionalCurlOptions = array();

  /**
   * The original user, before it was changed to a clean uid = 1 for testing purposes.
   *
   * @var object
   */
  protected $originalUser = NULL;

  /**
   * The original shutdown handlers array, before it was cleaned for testing purposes.
   *
   * @var array
   */
  protected $originalShutdownCallbacks = array();

  /**
   * HTTP authentication method
   */
  protected $httpauth_method = CURLAUTH_BASIC;

  /**
   * HTTP authentication credentials (<username>:<password>).
   */
  protected $httpauth_credentials = NULL;

  /**
   * The current session name, if available.
   */
  protected $session_name = NULL;

  /**
   * The current session ID, if available.
   */
  protected $session_id = NULL;

  /**
   * Whether the files were copied to the test files directory.
   */
  protected $generatedTestFiles = FALSE;

  /**
   * The number of redirects followed during the handling of a request.
   */
  protected $redirect_count;

  /**
   * Constructor for DrupalWebTestCase.
   */
  function __construct($test_id = NULL) {
    parent::__construct($test_id);
    $this->skipClasses[__CLASS__] = TRUE;
  }

  /**
   * Get a node from the database based on its title.
   *
   * @param title
   *   A node title, usually generated by $this->randomName().
   *
   * @return
   *   A node object matching $title.
   */
  function drupalGetNodeByTitle($title) {
    $nodes = node_load_multiple(array(), array('title' => $title));
    // Load the first node returned from the database.
    $returned_node = reset($nodes);
    return $returned_node;
  }

  /**
   * Creates a node based on default settings.
   *
   * @param $settings
   *   An associative array of settings to change from the defaults, keys are
   *   node properties, for example 'title' => 'Hello, world!'.
   * @return
   *   Created node object.
   */
  protected function drupalCreateNode($settings = array()) {
    // Populate defaults array.
    $settings += array(
      'body'      => array(LANGUAGE_NONE => array(array())),
      'title'     => $this->randomName(8),
      'comment'   => 2,
      'changed'   => REQUEST_TIME,
      'moderate'  => 0,
      'promote'   => 0,
      'revision'  => 1,
      'log'       => '',
      'status'    => 1,
      'sticky'    => 0,
      'type'      => 'page',
      'revisions' => NULL,
      'language'  => LANGUAGE_NONE,
    );

    // Use the original node's created time for existing nodes.
    if (isset($settings['created']) && !isset($settings['date'])) {
      $settings['date'] = format_date($settings['created'], 'custom', 'Y-m-d H:i:s O');
    }

    // If the node's user uid is not specified manually, use the currently
    // logged in user if available, or else the user running the test.
    if (!isset($settings['uid'])) {
      if ($this->loggedInUser) {
        $settings['uid'] = $this->loggedInUser->uid;
      }
      else {
        global $user;
        $settings['uid'] = $user->uid;
      }
    }

    // Merge body field value and format separately.
    $body = array(
      'value' => $this->randomName(32),
      'format' => filter_default_format(),
    );
    $settings['body'][$settings['language']][0] += $body;

    $node = (object) $settings;
    node_save($node);

    // Small hack to link revisions to our test user.
    db_update('node_revision')
      ->fields(array('uid' => $node->uid))
      ->condition('vid', $node->vid)
      ->execute();
    return $node;
  }

  /**
   * Creates a custom content type based on default settings.
   *
   * @param $settings
   *   An array of settings to change from the defaults.
   *   Example: 'type' => 'foo'.
   * @return
   *   Created content type.
   */
  protected function drupalCreateContentType($settings = array()) {
    // Find a non-existent random type name.
    do {
      $name = strtolower($this->randomName(8));
    } while (node_type_get_type($name));

    // Populate defaults array.
    $defaults = array(
      'type' => $name,
      'name' => $name,
      'base' => 'node_content',
      'description' => '',
      'help' => '',
      'title_label' => 'Title',
      'body_label' => 'Body',
      'has_title' => 1,
      'has_body' => 1,
    );
    // Imposed values for a custom type.
    $forced = array(
      'orig_type' => '',
      'old_type' => '',
      'module' => 'node',
      'custom' => 1,
      'modified' => 1,
      'locked' => 0,
    );
    $type = $forced + $settings + $defaults;
    $type = (object)$type;

    $saved_type = node_type_save($type);
    node_types_rebuild();
    menu_rebuild();

    $this->assertEqual($saved_type, SAVED_NEW, t('Created content type %type.', array('%type' => $type->type)));

    // Reset permissions so that permissions for this content type are available.
    $this->checkPermissions(array(), TRUE);

    return $type;
  }

  /**
   * Get a list files that can be used in tests.
   *
   * @param $type
   *   File type, possible values: 'binary', 'html', 'image', 'javascript', 'php', 'sql', 'text'.
   * @param $size
   *   File size in bytes to match. Please check the tests/files folder.
   * @return
   *   List of files that match filter.
   */
  protected function drupalGetTestFiles($type, $size = NULL) {
    if (empty($this->generatedTestFiles)) {
      // Generate binary test files.
      $lines = array(64, 1024);
      $count = 0;
      foreach ($lines as $line) {
        simpletest_generate_file('binary-' . $count++, 64, $line, 'binary');
      }

      // Generate text test files.
      $lines = array(16, 256, 1024, 2048, 20480);
      $count = 0;
      foreach ($lines as $line) {
        simpletest_generate_file('text-' . $count++, 64, $line);
      }

      // Copy other test files from simpletest.
      $original = drupal_get_path('module', 'simpletest') . '/files';
      $files = file_scan_directory($original, '/(html|image|javascript|php|sql)-.*/');
      $destination_path = file_directory_path('public');
      foreach ($files as $file) {
        file_unmanaged_copy($file->uri, $destination_path);
      }

      $this->generatedTestFiles = TRUE;
    }

    $files = array();
    // Make sure type is valid.
    if (in_array($type, array('binary', 'html', 'image', 'javascript', 'php', 'sql', 'text'))) {
      $files = file_scan_directory(file_directory_path('public'), '/' . $type . '\-.*/');

      // If size is set then remove any files that are not of that size.
      if ($size !== NULL) {
        foreach ($files as $file) {
          $stats = stat($file->uri);
          if ($stats['size'] != $size) {
            unset($files[$file->uri]);
          }
        }
      }
    }
    usort($files, array($this, 'drupalCompareFiles'));
    return $files;
  }

  /**
   * Compare two files based on size and file name.
   */
  protected function drupalCompareFiles($file1, $file2) {
    $compare_size = filesize($file1->uri) - filesize($file2->uri);
    if ($compare_size) {
      // Sort by file size.
      return $compare_size;
    }
    else {
      // The files were the same size, so sort alphabetically.
      return strnatcmp($file1->name, $file2->name);
    }
  }

  /**
   * Create a user with a given set of permissions. The permissions correspond to the
   * names given on the privileges page.
   *
   * @param $permissions
   *   Array of permission names to assign to user.
   * @return
   *   A fully loaded user object with pass_raw property, or FALSE if account
   *   creation fails.
   */
  protected function drupalCreateUser($permissions = array('access comments', 'access content', 'post comments', 'post comments without approval')) {
    // Create a role with the given permission set.
    if (!($rid = $this->drupalCreateRole($permissions))) {
      return FALSE;
    }

    // Create a user assigned to that role.
    $edit = array();
    $edit['name']   = $this->randomName();
    $edit['mail']   = $edit['name'] . '@example.com';
    $edit['roles']  = array($rid => $rid);
    $edit['pass']   = user_password();
    $edit['status'] = 1;

    $account = user_save(drupal_anonymous_user(), $edit);

    $this->assertTrue(!empty($account->uid), t('User created with name %name and pass %pass', array('%name' => $edit['name'], '%pass' => $edit['pass'])), t('User login'));
    if (empty($account->uid)) {
      return FALSE;
    }

    // Add the raw password so that we can log in as this user.
    $account->pass_raw = $edit['pass'];
    return $account;
  }

  /**
   * Internal helper function; Create a role with specified permissions.
   *
   * @param $permissions
   *   Array of permission names to assign to role.
   * @param $name
   *   (optional) String for the name of the role.  Defaults to a random string.
   * @return
   *   Role ID of newly created role, or FALSE if role creation failed.
   */
  protected function drupalCreateRole(array $permissions, $name = NULL) {
    // Generate random name if it was not passed.
    if (!$name) {
      $name = $this->randomName();
    }

    // Check the all the permissions strings are valid.
    if (!$this->checkPermissions($permissions)) {
      return FALSE;
    }

    // Create new role.
    $role = new stdClass();
    $role->name = $name;
    user_role_save($role);
    user_role_grant_permissions($role->rid, $permissions);

    $this->assertTrue(isset($role->rid), t('Created role of name: @name, id: @rid', array('@name' => $name, '@rid' => (isset($role->rid) ? $role->rid : t('-n/a-')))), t('Role'));
    if ($role && !empty($role->rid)) {
      $count = db_query('SELECT COUNT(*) FROM {role_permission} WHERE rid = :rid', array(':rid' => $role->rid))->fetchField();
      $this->assertTrue($count == count($permissions), t('Created permissions: @perms', array('@perms' => implode(', ', $permissions))), t('Role'));
      return $role->rid;
    }
    else {
      return FALSE;
    }
  }

  /**
   * Check to make sure that the array of permissions are valid.
   *
   * @param $permissions
   *   Permissions to check.