diff --git a/core/modules/aggregator/aggregator.admin.inc b/core/modules/aggregator/aggregator.admin.inc
index df25c351cb54c164302285a3d180486317370b15..3612e0c8e916d4b118b697607b155556a3b53599 100644
--- a/core/modules/aggregator/aggregator.admin.inc
+++ b/core/modules/aggregator/aggregator.admin.inc
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Admin page callbacks for the aggregator module.
+ * Administration page callbacks for the Aggregator module.
  */
 
 use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
@@ -11,6 +11,9 @@
 /**
  * Page callback: Displays the aggregator administration page.
  *
+ * @return string
+ *   A HTML-formatted string with administration page content.
+ *
  * @see aggregator_menu()
  */
 function aggregator_admin_overview() {
@@ -92,8 +95,8 @@ function aggregator_view() {
  * Form constructor for adding and editing feed sources.
  *
  * @param $feed
- *   If editing a feed, the feed to edit as a PHP stdClass value; if adding a
- *   new feed, NULL.
+ *   (optional) If editing a feed, the feed to edit as a PHP stdClass value; if
+ *   adding a new feed, NULL. Defaults to NULL.
  *
  * @ingroup forms
  * @see aggregator_menu()
@@ -199,6 +202,7 @@ function aggregator_form_feed_validate($form, &$form_state) {
  * Form submission handler for aggregator_form_feed().
  *
  * @see aggregator_form_feed_validate()
+ *
  * @todo Add delete confirmation dialog.
  */
 function aggregator_form_feed_submit($form, &$form_state) {
@@ -641,6 +645,7 @@ function aggregator_form_category_validate($form, &$form_state) {
  * Form submission handler for aggregator_form_category().
  *
  * @see aggregator_form_category_validate()
+ *
  * @todo Add delete confirmation dialog.
  */
 function aggregator_form_category_submit($form, &$form_state) {
diff --git a/core/modules/aggregator/aggregator.module b/core/modules/aggregator/aggregator.module
index a1e1dbf12db7d82bcfd8dad1304fd009d1dee76d..35cdc19cef278c81b67047b0e70c5c3b3aecee4b 100644
--- a/core/modules/aggregator/aggregator.module
+++ b/core/modules/aggregator/aggregator.module
@@ -267,13 +267,13 @@ function aggregator_menu() {
 }
 
 /**
- * Title callback: Returns a title for aggregatory category pages.
+ * Title callback: Returns a title for aggregator category pages.
  *
  * @param $category
  *   An aggregator category.
  *
  * @return
- *   An aggregator category title.
+ *   A string with the aggregator category title.
  */
 function _aggregator_category_title($category) {
   return $category['title'];
@@ -652,7 +652,7 @@ function theme_aggregator_block_item($variables) {
 }
 
 /**
- * Safely renders HTML content, as allowed.
+ * Renders the HTML content safely, as allowed.
  *
  * @param $value
  *   The content to be filtered.
@@ -668,7 +668,7 @@ function aggregator_filter_xss($value) {
  * Checks and sanitizes the aggregator configuration.
  *
  * Goes through all fetchers, parsers and processors and checks whether they
- * are available. If one is missing resets to standard configuration.
+ * are available. If one is missing, resets to standard configuration.
  *
  * @return
  *   TRUE if this function resets the configuration; FALSE if not.
@@ -707,7 +707,7 @@ function aggregator_sanitize_configuration() {
  *   Items count.
  *
  * @return
- *   Plural-formatted "@count items"
+ *   A string that is plural-formatted as "@count items".
  */
 function _aggregator_items($count) {
   return format_plural($count, '1 item', '@count items');
diff --git a/core/modules/aggregator/aggregator.pages.inc b/core/modules/aggregator/aggregator.pages.inc
index fb1f5208887e064dd53f779383cc7461099f6e20..a49a666f583b02545fe8df1b7465b4c0256e1310 100644
--- a/core/modules/aggregator/aggregator.pages.inc
+++ b/core/modules/aggregator/aggregator.pages.inc
@@ -2,12 +2,15 @@
 
 /**
  * @file
- * User page callbacks for the aggregator module.
+ * User page callbacks for the Aggregator module.
  */
 
 /**
  * Page callback: Displays the most recent items gathered from any feed.
  *
+ * @return string
+ *   The rendered list of items for the feed.
+ *
  * @see aggregator_menu()
  */
 function aggregator_page_last() {
@@ -19,11 +22,14 @@ function aggregator_page_last() {
 }
 
 /**
- * Page callback: Displays all the items captured from a particular feed.
+ * Page callback: Displays all the items captured from the particular feed.
  *
  * @param $feed
  *   The feed for which to display all items.
  *
+ * @return string
+ *   The rendered list of items for the feed.
+ *
  * @see aggregator_menu()
  */
 function aggregator_page_source($feed) {
@@ -41,7 +47,10 @@ function aggregator_page_source($feed) {
  * Form constructor to show all items captured from a feed.
  *
  * @param $feed
- *   The feed for which to list all the aggregated items.
+ *   The feed for which to list all of the aggregated items.
+ *
+ * @return string
+ *   The rendered list of items for the feed.
  *
  * @see aggregator_menu()
  * @see aggregator_page_source()
@@ -55,7 +64,10 @@ function aggregator_page_source_form($form, $form_state, $feed) {
  * Form constructor to list items aggregated in a category.
  *
  * @param $category
- *   The category for which to list all the aggregated items.
+ *   The category for which to list all of the aggregated items.
+ *
+ * @return string
+ *   The rendered list of items for the feed.
  *
  * @see aggregator_menu()
  * @ingroup forms
@@ -74,7 +86,10 @@ function aggregator_page_category($category) {
  * Form constructor to list items aggregated in a category.
  *
  * @param $category
- *   The category for which to list all the aggregated items.
+ *   The category for which to list all of the aggregated items.
+ *
+ * @return string
+ *   The rendered list of items for the feed.
  *
  * @see aggregator_menu()
  * @see aggregator_page_category()
@@ -162,7 +177,7 @@ function aggregator_load_feed_items($type, $data = NULL) {
  *   The feed source URL.
  *
  * @return
- *   The rendered list of items for a feed.
+ *   The rendered list of items for the feed.
  */
 function _aggregator_page_list($items, $op, $feed_source = '') {
   if (user_access('administer news feeds') && ($op == 'categorize')) {
@@ -184,13 +199,17 @@ function _aggregator_page_list($items, $op, $feed_source = '') {
 /**
  * Form constructor to build the page list form.
  *
- * @param $items
+ * @param array $items
  *   An array of the feed items.
- * @param $feed_source
- *   The feed source URL.
+ * @param string $feed_source
+ *   (optional) The feed source URL. Defaults to an empty string.
+ *
+ * @return array
+ *   An array of FAPI elements.
  *
- * @ingroup forms
  * @see aggregator_categorize_items_submit()
+ * @see theme_aggregator_categorize_items()
+ * @ingroup forms
  */
 function aggregator_categorize_items($items, $feed_source = '') {
   $form['#submit'][] = 'aggregator_categorize_items_submit';
@@ -346,7 +365,10 @@ function template_preprocess_aggregator_item(&$variables) {
 }
 
 /**
- * Page callback: Displays all the feeds used by the aggregator.
+ * Page callback: Displays all the feeds used by the Aggregator module.
+ *
+ * @return string
+ *   An HTML-formatted string.
  *
  * @see aggregator_menu()
  */
@@ -373,7 +395,10 @@ function aggregator_page_sources() {
 }
 
 /**
- * Page callback: Displays all the categories used by the aggregator.
+ * Page callback: Displays all the categories used by the Aggregator module.
+ *
+ * @return string
+ *   An HTML formatted string.
  *
  * @see aggregator_menu()
  */
@@ -400,6 +425,9 @@ function aggregator_page_categories() {
 /**
  * Page callback: Generates an RSS 0.92 feed of aggregator items or categories.
  *
+ * @return string
+ *   An HTML formatted string.
+ *
  * @see aggregator_menu()
  */
 function aggregator_page_rss() {
@@ -472,8 +500,11 @@ function theme_aggregator_page_rss($variables) {
  * Page callback: Generates an OPML representation of all feeds.
  *
  * @param $cid
- *   If set, feeds are exported only from a category with this ID. Otherwise,
- *   all feeds are exported.
+ *   (optional) If set, feeds are exported only from a category with this ID.
+ *   Otherwise, all feeds are exported. Defaults to NULL.
+ *
+ * @return string
+ *   An OPML formatted string.
  *
  * @see aggregator_menu()
  */
@@ -490,14 +521,12 @@ function aggregator_page_opml($cid = NULL) {
 }
 
 /**
- * Prints the OPML page for a feed.
+ * Prints the OPML page for the feed.
  *
- * @param $variables
+ * @param array $variables
  *   An associative array containing:
  *   - feeds: An array of the feeds to theme.
  *
- * @return void
- *
  * @ingroup themeable
  */
 function theme_aggregator_page_opml($variables) {
diff --git a/core/modules/aggregator/aggregator.processor.inc b/core/modules/aggregator/aggregator.processor.inc
index f00edc531757dc42a5a7097e21372e5c3a59f52b..f585a3c1d95835b007e23778ecd1de852e6d3ac9 100644
--- a/core/modules/aggregator/aggregator.processor.inc
+++ b/core/modules/aggregator/aggregator.processor.inc
@@ -133,6 +133,12 @@ function aggregator_form_aggregator_admin_form_alter(&$form, $form_state) {
  *
  * Callback for drupal_map_assoc() within
  * aggregator_form_aggregator_admin_form_alter().
+ *
+ * @param int $length
+ *   The desired length of teaser text, in bytes.
+ *
+ * @return string
+ *   A translated string explaining the teaser string length.
  */
 function _aggregator_characters($length) {
   return ($length == 0) ? t('Unlimited') : format_plural($length, '1 character', '@count characters');
diff --git a/core/modules/aggregator/aggregator.theme-rtl.css b/core/modules/aggregator/aggregator.theme-rtl.css
index f02ae91b2dfb69a4b8f48cc5ebd88ceb2a0c8369..4c7767de01e2d0b27dcfa715a992e6b8e50efbbf 100644
--- a/core/modules/aggregator/aggregator.theme-rtl.css
+++ b/core/modules/aggregator/aggregator.theme-rtl.css
@@ -1,3 +1,7 @@
+/**
+ * Right-to-Left styles for theme in the Aggregator module.
+ */
+
 .aggregator .feed-icon {
   float: left;
 }
diff --git a/core/modules/aggregator/aggregator.theme.css b/core/modules/aggregator/aggregator.theme.css
index e2182acf7c72f6e9c04f4f7e5ca51dbbf11fb0fc..2c5e612eb536049f06ce1ad6f541aa6fe12e8ab6 100644
--- a/core/modules/aggregator/aggregator.theme.css
+++ b/core/modules/aggregator/aggregator.theme.css
@@ -1,3 +1,7 @@
+/**
+ * Styles for theme in the Aggregator module.
+ */
+
 .aggregator .feed-icon {
   float: right; /* LTR */
   display: block;
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/FetcherInterface.php b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/FetcherInterface.php
index 39fc19df2aee5a89e01e1f8de1d3fe709eae81f7..6c79a59a4dc84ce5caa2b0515543850b44b0b471 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/FetcherInterface.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/FetcherInterface.php
@@ -1,4 +1,5 @@
 <?php
+
 /**
  * @file
  * Definition of Drupal\aggregator\Plugin\FetcherInterface.
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AddFeedTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AddFeedTest.php
index 69ad6d6ba7bfb2c73e324d540f0c90dac5e9d0bf..9f6fc24b0514640b64fea8da666c37586e60be4b 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AddFeedTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AddFeedTest.php
@@ -8,7 +8,7 @@
 namespace Drupal\aggregator\Tests;
 
 /**
- * Tests aggregator feed adding.
+ * Tests adding aggregator feeds.
  */
 class AddFeedTest extends AggregatorTestBase {
   public static function getInfo() {
@@ -20,7 +20,7 @@ public static function getInfo() {
   }
 
   /**
-   * Create a feed, ensure that it is unique, check the source, and delete the feed.
+   * Creates and ensures that a feed is unique, checks source, and deletes feed.
    */
   function testAddFeed() {
     $feed = $this->createFeed();
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php
index 503b9a1f0dba6a26281e43ad049f281c4d6ea8d8..dbddd697622ab1f85a8afd96377fe1e515c1ce6b 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php
@@ -8,7 +8,7 @@
 namespace Drupal\aggregator\Tests;
 
 /**
- * Tests aggregator configuration settings.
+ * Tests functionality of the configuration settings in the Aggregator module.
  */
 class AggregatorConfigurationTest extends AggregatorTestBase {
   public static function getInfo() {
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php
index 47617a0be312b497b9926c2342a05181b755f0e5..94e113ec193ca544f524e0535ac5d3a73e4200af 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests functionality of the cron process in the Aggregator module.
+ */
 class AggregatorCronTest extends AggregatorTestBase {
   public static function getInfo() {
     return array(
@@ -17,7 +20,7 @@ public static function getInfo() {
   }
 
   /**
-   * Add feeds update them on cron.
+   * Adds feeds and updates them via cron process.
    */
   public function testCron() {
     // Create feed and test basic updating on cron.
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php
index 50895dc03d3aae5d06dff5a5794414d813595ac0..cd083b7fd5fdcf6588cf74d0e47178a846f4e506 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests rendering functionality in the Aggregator module.
+ */
 class AggregatorRenderingTest extends AggregatorTestBase {
 
   /**
@@ -25,9 +28,9 @@ public static function getInfo() {
   }
 
   /**
-   * Add a feed block to the page and checks its links.
+   * Adds a feed block to the page and checks its links.
    *
-   * TODO: Test the category block as well.
+   * @todo Test the category block as well.
    */
   public function testBlockLinks() {
     // Create feed.
@@ -79,7 +82,7 @@ public function testBlockLinks() {
   }
 
   /**
-   * Create a feed and check that feed's page.
+   * Creates a feed and checks that feed's page.
    */
   public function testFeedPage() {
     // Increase the number of items published in the rss.xml feed so we have
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php
index 8fb98a9630c0a60bf9838981ef9f5a11794019a7..faf56279e2c6c953446b6eeb2c88e651f9ab8bb7 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php
@@ -10,7 +10,7 @@
 use Drupal\simpletest\WebTestBase;
 
 /**
- * Defines a base class for testing aggregator.module.
+ * Defines a base class for testing the Aggregator module.
  */
 abstract class AggregatorTestBase extends WebTestBase {
 
@@ -34,10 +34,15 @@ function setUp() {
   }
 
   /**
-   * Create an aggregator feed (simulate form submission on admin/config/services/aggregator/add/feed).
+   * Creates an aggregator feed.
+   *
+   * This method simulates the form submission on path
+   * admin/config/services/aggregator/add/feed.
    *
    * @param $feed_url
-   *   If given, feed will be created with this URL, otherwise /rss.xml will be used.
+   *   (optional) If given, feed will be created with this URL, otherwise
+   *   /rss.xml will be used. Defaults to NULL.
+   *
    * @return $feed
    *   Full feed object if possible.
    *
@@ -54,7 +59,7 @@ function createFeed($feed_url = NULL) {
   }
 
   /**
-   * Delete an aggregator feed.
+   * Deletes an aggregator feed.
    *
    * @param $feed
    *   Feed object representing the feed.
@@ -65,10 +70,12 @@ function deleteFeed($feed) {
   }
 
   /**
-   * Return a randomly generated feed edit array.
+   * Returns a randomly generated feed edit array.
    *
    * @param $feed_url
-   *   If given, feed will be created with this URL, otherwise /rss.xml will be used.
+   *   (optional) If given, feed will be created with this URL, otherwise
+   *   /rss.xml will be used. Defaults to NULL.
+   *
    * @return
    *   A feed array.
    */
@@ -89,7 +96,7 @@ function getFeedEditArray($feed_url = NULL) {
   }
 
   /**
-   * Return the count of the randomly created feed array.
+   * Returns the count of the randomly created feed array.
    *
    * @return
    *   Number of feed items on default feed created by createFeed().
@@ -101,10 +108,13 @@ function getDefaultFeedItemCount() {
   }
 
   /**
-   * Update feed items (simulate click to admin/config/services/aggregator/update/$fid).
+   * Updates the feed items.
+   *
+   * This method simulates a click to
+   * admin/config/services/aggregator/update/$fid.
    *
    * @param $feed
-   *   Feed object representing the feed.
+   *   Feed object representing the feed, passed by reference.
    * @param $expected_count
    *   Expected number of feed items.
    */
@@ -133,7 +143,7 @@ function updateFeedItems(&$feed, $expected_count) {
   }
 
   /**
-   * Confirm item removal from a feed.
+   * Confirms an item removal from a feed.
    *
    * @param $feed
    *   Feed object representing the feed.
@@ -144,7 +154,7 @@ function removeFeedItems($feed) {
   }
 
   /**
-   * Add and remove feed items and ensure that the count is zero.
+   * Adds and removes feed items and ensure that the count is zero.
    *
    * @param $feed
    *   Feed object representing the feed.
@@ -161,7 +171,7 @@ function updateAndRemove($feed, $expected_count) {
   }
 
   /**
-   * Pull feed categories from aggregator_category_feed table.
+   * Pulls feed categories from {aggregator_category_feed} table.
    *
    * @param $feed
    *   Feed object representing the feed.
@@ -175,7 +185,11 @@ function getFeedCategories($feed) {
   }
 
   /**
-   * Pull categories from aggregator_category table.
+   * Pulls categories from {aggregator_category} table.
+   *
+   * @return array
+   *   An associative array keyed by category ID and values are set to the
+   *   category names.
    */
   function getCategories() {
     $categories = array();
@@ -186,14 +200,14 @@ function getCategories() {
     return $categories;
   }
 
-
   /**
-   * Check if the feed name and url is unique.
+   * Checks whether the feed name and URL are unique.
    *
    * @param $feed_name
    *   String containing the feed name to check.
    * @param $feed_url
    *   String containing the feed url to check.
+   *
    * @return
    *   TRUE if feed is unique.
    */
@@ -203,10 +217,11 @@ function uniqueFeed($feed_name, $feed_url) {
   }
 
   /**
-   * Create a valid OPML file from an array of feeds.
+   * Creates a valid OPML file from an array of feeds.
    *
    * @param $feeds
    *   An array of feeds.
+   *
    * @return
    *   Path to valid OPML file.
    */
@@ -244,7 +259,7 @@ function getValidOpml($feeds) {
   }
 
   /**
-   * Create an invalid OPML file.
+   * Creates an invalid OPML file.
    *
    * @return
    *   Path to invalid OPML file.
@@ -261,7 +276,7 @@ function getInvalidOpml() {
   }
 
   /**
-   * Create a valid but empty OPML file.
+   * Creates a valid but empty OPML file.
    *
    * @return
    *   Path to empty OPML file.
@@ -300,7 +315,7 @@ function getHtmlEntitiesSample() {
    * Creates sample article nodes.
    *
    * @param $count
-   *   (optional) The number of nodes to generate.
+   *   (optional) The number of nodes to generate. Defaults to five.
    */
   function createSampleNodes($count = 5) {
     $langcode = LANGUAGE_NOT_SPECIFIED;
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedItemTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedItemTest.php
index ae7179977d0de492bb83b77ae39faaafd07eedb7..a6a1dab3947e412d427704147b81e6c7546781dc 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedItemTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedItemTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests categorization functionality in the Aggregator module.
+ */
 class CategorizeFeedItemTest extends AggregatorTestBase {
   public static function getInfo() {
     return array(
@@ -17,6 +20,8 @@ public static function getInfo() {
   }
 
   /**
+   * Checks that children of a feed inherit a defined category.
+   *
    * If a feed has a category, make sure that the children inherit that
    * categorization.
    */
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedTest.php
index 977dbcbdf3e3560a2f1af76a5d17f2bb356a85e1..9636d559bf0c16bdd9844a12675bc68cfccf1673 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/CategorizeFeedTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests the categorize feed functionality in the Aggregator module.
+ */
 class CategorizeFeedTest extends AggregatorTestBase {
   public static function getInfo() {
     return array(
@@ -17,7 +20,7 @@ public static function getInfo() {
   }
 
   /**
-   * Create a feed and make sure you can add more than one category to it.
+   * Creates a feed and makes sure you can add more than one category to it.
    */
   function testCategorizeFeed() {
 
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/FeedParserTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/FeedParserTest.php
index 907bc3a1326e394e453c02da263272e1e8984102..ac8c5fa285a09c892d35a54a2bfd34a4962111a4 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/FeedParserTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/FeedParserTest.php
@@ -8,7 +8,7 @@
 namespace Drupal\aggregator\Tests;
 
 /**
- * Tests for feed parsing.
+ * Tests feed parsing in the Aggregator module.
  */
 class FeedParserTest extends AggregatorTestBase {
   public static function getInfo() {
@@ -28,7 +28,7 @@ function setUp() {
   }
 
   /**
-   * Test a feed that uses the RSS 0.91 format.
+   * Tests a feed that uses the RSS 0.91 format.
    */
   function testRSS091Sample() {
     $feed = $this->createFeed($this->getRSS091Sample());
@@ -50,7 +50,7 @@ function testRSS091Sample() {
   }
 
   /**
-   * Test a feed that uses the Atom format.
+   * Tests a feed that uses the Atom format.
    */
   function testAtomSample() {
     $feed = $this->createFeed($this->getAtomSample());
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/ImportOpmlTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/ImportOpmlTest.php
index aa96ecf468e11bc4704bb7379317b63ef09000eb..5eb110faac6e23027bcb4949fd6b786d72e0b072 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/ImportOpmlTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/ImportOpmlTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests importing feeds from OPML functionality for the Aggregator module.
+ */
 class ImportOpmlTest extends AggregatorTestBase {
 
   /**
@@ -32,7 +35,7 @@ function setUp() {
   }
 
   /**
-   * Open OPML import form.
+   * Opens OPML import form.
    */
   function openImportForm() {
     db_delete('aggregator_category')->execute();
@@ -65,7 +68,7 @@ function openImportForm() {
   }
 
   /**
-   * Submit form filled with invalid fields.
+   * Submits form filled with invalid fields.
    */
   function validateImportFormFields() {
     $before = db_query('SELECT COUNT(*) FROM {aggregator_feed}')->fetchField();
@@ -91,7 +94,7 @@ function validateImportFormFields() {
   }
 
   /**
-   * Submit form with invalid, empty and valid OPML files.
+   * Submits form with invalid, empty, and valid OPML files.
    */
   function submitImportForm() {
     $before = db_query('SELECT COUNT(*) FROM {aggregator_feed}')->fetchField();
@@ -150,6 +153,9 @@ function submitImportForm() {
     $this->assertTrue($category, 'Categories are correct.');
   }
 
+  /**
+   * Tests the import of an OPML file.
+   */
   function testOpmlImport() {
     $this->openImportForm();
     $this->validateImportFormFields();
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedItemTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedItemTest.php
index 32433ae2fbe02d6c0121e5e9d683a86ac1c66606..b27432d70ac8d9accc145765ae0b6d79a9a61414 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedItemTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedItemTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests functionality of removing a feed item in the Aggregator module.
+ */
 class RemoveFeedItemTest extends AggregatorTestBase {
   public static function getInfo() {
     return array(
@@ -17,7 +20,7 @@ public static function getInfo() {
   }
 
   /**
-   * Test running "remove items" from the 'admin/config/services/aggregator' page.
+   * Tests running "remove items" from 'admin/config/services/aggregator' page.
    */
   function testRemoveFeedItem() {
     // Create a bunch of test feeds.
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedTest.php
index 983ec571f8367bc21f0c8fe06234394a51248231..b4ff56cd654f554b8d2d22dad30ef5c4608e24d3 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/RemoveFeedTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests functionality for removing feeds in the Aggregator module.
+ */
 class RemoveFeedTest extends AggregatorTestBase {
   public static function getInfo() {
     return array(
@@ -17,7 +20,7 @@ public static function getInfo() {
   }
 
   /**
-   * Remove a feed and ensure that all it services are removed.
+   * Removes a feed and ensures that all of its services are removed.
    */
   function testRemoveFeed() {
     $feed = $this->createFeed();
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedItemTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedItemTest.php
index bf1d2be494576e058fb75e2593dd1ddaaa25f5ad..42c1c15d75124b1425fd7fcd51a59ac38541f60f 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedItemTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedItemTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests functionality of updating a feed item in the Aggregator module.
+ */
 class UpdateFeedItemTest extends AggregatorTestBase {
   public static function getInfo() {
     return array(
@@ -17,7 +20,7 @@ public static function getInfo() {
   }
 
   /**
-   * Test running "update items" from the 'admin/config/services/aggregator' page.
+   * Tests running "update items" from 'admin/config/services/aggregator' page.
    */
   function testUpdateFeedItem() {
     $this->createSampleNodes();
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedTest.php
index fd8a828f3f4a870d1a897abb7abac1cc44d897ed..751daa3c31511c5ff060a9eb4718de7e0a301bb2 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/UpdateFeedTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\aggregator\Tests;
 
+/**
+ * Tests functionality of updating the feed in the Aggregator module.
+ */
 class UpdateFeedTest extends AggregatorTestBase {
   public static function getInfo() {
     return array(
@@ -17,7 +20,7 @@ public static function getInfo() {
   }
 
   /**
-   * Create a feed and attempt to update it.
+   * Creates a feed and attempts to update it.
    */
   function testUpdateFeed() {
     $remamining_fields = array('title', 'url', '');