diff --git a/core/modules/config/config.api.php b/core/modules/config/config.api.php
index d83684c..e5dba3d 100644
--- a/core/modules/config/config.api.php
+++ b/core/modules/config/config.api.php
@@ -72,11 +72,14 @@ function hook_config_import_change($name, $new_config, $old_config) {
   $id = substr($name, strlen($entity_info['config prefix']) + 1);
   $config_test = entity_load('config_test', $id);
 
+  // Store the original config, and iterate through each property to store it.
   $config_test->original = clone $config_test;
   foreach ($old_config->get() as $property => $value) {
     $config_test->original->$property = $value;
   }
 
+  // Iterate through each property of the new config, copying it to the
+  // configurable test object.
   foreach ($new_config->get() as $property => $value) {
     $config_test->$property = $value;
   }
diff --git a/core/modules/config/lib/Drupal/config/ConfigStorageController.php b/core/modules/config/lib/Drupal/config/ConfigStorageController.php
index 57c2583..12d62b4 100644
--- a/core/modules/config/lib/Drupal/config/ConfigStorageController.php
+++ b/core/modules/config/lib/Drupal/config/ConfigStorageController.php
@@ -137,7 +137,7 @@ public function loadByProperties(array $values = array()) {
    * Drupal\taxonomy\TermStorageController::buildQuery() for examples.
    *
    * @param $ids
-   *   An array of entity IDs, or FALSE to load all entities.
+   *   An array of entity IDs, or NULL to load all entities.
    * @param $revision_id
    *   The ID of the revision to load, or FALSE if this query is asking for the
    *   most current revision(s).
@@ -149,6 +149,7 @@ protected function buildQuery($ids, $revision_id = FALSE) {
     $config_class = $this->entityInfo['entity class'];
     $prefix = $this->entityInfo['config prefix'] . '.';
 
+    // Load all of the configurables.
     if ($ids === NULL) {
       $names = drupal_container()->get('config.storage')->listAll($prefix);
       $result = array();
@@ -161,6 +162,7 @@ protected function buildQuery($ids, $revision_id = FALSE) {
     else {
       $result = array();
       foreach ($ids as $id) {
+        // Add the prefix to the ID to serve as the configurable name.
         $config = config($prefix . $id);
         if (!$config->isNew()) {
           $result[$id] = new $config_class($config->get(), $this->entityType);
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigConfigurableTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigConfigurableTest.php
index 0867812..3e73528 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigConfigurableTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigConfigurableTest.php
@@ -14,6 +14,11 @@
  */
 class ConfigConfigurableTest extends WebTestBase {
 
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
   public static $modules = array('config_test');
 
   public static function getInfo() {
@@ -28,52 +33,56 @@ public static function getInfo() {
    * Tests basic CRUD operations through the UI.
    */
   function testCRUD() {
+    $id = strtolower($this->randomName());
+    $label1 = $this->randomName();
+    $label2 = $this->randomName();
+    $label3 = $this->randomName();
+
     // Create a configurable entity.
-    $id = 'thingie';
     $edit = array(
       'id' => $id,
-      'label' => 'Thingie',
+      'label' => $label1,
     );
     $this->drupalPost('admin/structure/config_test/add', $edit, 'Save');
     $this->assertResponse(200);
-    $this->assertText('Thingie');
+    $this->assertText($label1);
 
     // Update the configurable entity.
     $this->assertLinkByHref('admin/structure/config_test/manage/' . $id);
     $edit = array(
-      'label' => 'Thongie',
+      'label' => $label2,
     );
     $this->drupalPost('admin/structure/config_test/manage/' . $id, $edit, 'Save');
     $this->assertResponse(200);
-    $this->assertNoText('Thingie');
-    $this->assertText('Thongie');
+    $this->assertNoText($label1);
+    $this->assertText($label2);
 
     // Delete the configurable entity.
     $this->assertLinkByHref('admin/structure/config_test/manage/' . $id . '/delete');
     $this->drupalPost('admin/structure/config_test/manage/' . $id . '/delete', array(), 'Delete');
     $this->assertResponse(200);
-    $this->assertNoText('Thingie');
-    $this->assertNoText('Thongie');
+    $this->assertNoText($label1);
+    $this->assertNoText($label2);
 
     // Re-create a configurable entity.
     $edit = array(
       'id' => $id,
-      'label' => 'Thingie',
+      'label' => $label1,
     );
     $this->drupalPost('admin/structure/config_test/add', $edit, 'Save');
     $this->assertResponse(200);
-    $this->assertText('Thingie');
+    $this->assertText($label1);
 
     // Rename the configurable entity's ID/machine name.
     $this->assertLinkByHref('admin/structure/config_test/manage/' . $id);
-    $new_id = 'zingie';
     $edit = array(
-      'id' => $new_id,
-      'label' => 'Zingie',
+      'id' => strtolower($this->randomName()),
+      'label' => $label3,
     );
     $this->drupalPost('admin/structure/config_test/manage/' . $id, $edit, 'Save');
     $this->assertResponse(200);
-    $this->assertNoText('Thingie');
-    $this->assertText('Zingie');
+    $this->assertNoText($label1);
+    $this->assertText($label3);
   }
+
 }
diff --git a/core/modules/config/tests/config_test/config_test.module b/core/modules/config/tests/config_test/config_test.module
index e5550d0..5d422ad 100644
--- a/core/modules/config/tests/config_test/config_test.module
+++ b/core/modules/config/tests/config_test/config_test.module
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Provides Config module hook implementations for testing purposes.
+ */
+
 use Drupal\config_test\ConfigTest;
 
 require_once dirname(__FILE__) . '/config_test.hooks.inc';
@@ -35,11 +40,14 @@ function config_test_config_import_change($name, $new_config, $old_config) {
   $id = substr($name, strlen($entity_info['config prefix']) + 1);
   $config_test = entity_load('config_test', $id);
 
+  // Store the original config, and iterate through each property to store it.
   $config_test->original = clone $config_test;
   foreach ($old_config->get() as $property => $value) {
     $config_test->original->$property = $value;
   }
 
+  // Iterate through each property of the new config, copying it to the
+  // configurable test object.
   foreach ($new_config->get() as $property => $value) {
     $config_test->$property = $value;
   }
diff --git a/core/modules/config/tests/config_test/lib/Drupal/config_test/ConfigTest.php b/core/modules/config/tests/config_test/lib/Drupal/config_test/ConfigTest.php
index 7431e4b..ca3550c 100644
--- a/core/modules/config/tests/config_test/lib/Drupal/config_test/ConfigTest.php
+++ b/core/modules/config/tests/config_test/lib/Drupal/config_test/ConfigTest.php
@@ -14,10 +14,25 @@
  */
 class ConfigTest extends ConfigurableBase {
 
+  /**
+   * The machine name for the configurable.
+   *
+   * @var string
+   */
   public $id;
 
+  /**
+   * The UUID for the configurable.
+   *
+   * @var string
+   */
   public $uuid;
 
+  /**
+   * The human-readable name of the configurable.
+   *
+   * @var string
+   */
   public $label;
 
   /**