diff --git a/core/modules/system/lib/Drupal/system/SystemConfigSubscriber.php b/core/modules/system/lib/Drupal/system/SystemConfigSubscriber.php
index f9965f9..a713f96 100644
--- a/core/modules/system/lib/Drupal/system/SystemConfigSubscriber.php
+++ b/core/modules/system/lib/Drupal/system/SystemConfigSubscriber.php
@@ -31,7 +31,7 @@ static function getSubscribedEvents() {
   public function onConfigImporterValidate(ConfigImporterEvent $event) {
     $importer = $event->getConfigImporter();
     $importList = $importer->getStorageComparer()->getSourceStorage()->listAll();
-    if (empty($importerList)) {
+    if (empty($importList)) {
       throw new ConfigImporterException("This import will delete all your active configuration, I'm bailing out now.");
     }
   }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Ajax/ElementValidationTest.php b/core/modules/system/lib/Drupal/system/Tests/Ajax/ElementValidationTest.php
index 81ed62d..a6e9daa 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Ajax/ElementValidationTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Ajax/ElementValidationTest.php
@@ -28,11 +28,10 @@ public static function getInfo() {
    * Ajax-enabled field fails due to the required field being empty.
    */
   function testAjaxElementValidation() {
-    $web_user = $this->drupalCreateUser();
     $edit = array('drivertext' => t('some dumb text'));
 
     // Post with 'drivertext' as the triggering element.
-    $post_result = $this->drupalPostAjaxForm('ajax_validation_test', $edit, 'drivertext');
+    $this->drupalPostAjaxForm('ajax_validation_test', $edit, 'drivertext');
     // Look for a validation failure in the resultant JSON.
     $this->assertNoText(t('Error message'), 'No error message in resultant JSON');
     $this->assertText('ajax_forms_test_validation_form_callback invoked', 'The correct callback was invoked');
@@ -41,7 +40,7 @@ function testAjaxElementValidation() {
     $edit = array('drivernumber' => 12345);
 
     // Post with 'drivernumber' as the triggering element.
-    $post_result = $this->drupalPostAjaxForm('ajax_validation_test', $edit, 'drivernumber');
+    $this->drupalPostAjaxForm('ajax_validation_test', $edit, 'drivernumber');
     // Look for a validation failure in the resultant JSON.
     $this->assertNoText(t('Error message'), 'No error message in resultant JSON');
     $this->assertText('ajax_forms_test_validation_number_form_callback invoked', 'The correct callback was invoked');
diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php
index 0aa4d5b..da14f5c 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php
@@ -76,7 +76,7 @@ static function addSampleData() {
       ))
       ->execute();
 
-    $ringo = db_insert('test')
+    db_insert('test')
       ->fields(array(
         'name' => 'Ringo',
         'age' => 28,
diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/SelectOrderedTest.php b/core/modules/system/lib/Drupal/system/Tests/Database/SelectOrderedTest.php
index 62d4d2a..9e20c8a 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/SelectOrderedTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/SelectOrderedTest.php
@@ -25,7 +25,7 @@ public static function getInfo() {
    */
   function testSimpleSelectOrdered() {
     $query = db_select('test');
-    $name_field = $query->addField('test', 'name');
+    $query->addField('test', 'name');
     $age_field = $query->addField('test', 'age', 'age');
     $query->orderBy($age_field);
     $result = $query->execute();
@@ -46,7 +46,7 @@ function testSimpleSelectOrdered() {
    */
   function testSimpleSelectMultiOrdered() {
     $query = db_select('test');
-    $name_field = $query->addField('test', 'name');
+    $query->addField('test', 'name');
     $age_field = $query->addField('test', 'age', 'age');
     $job_field = $query->addField('test', 'job');
     $query->orderBy($job_field);
@@ -77,7 +77,7 @@ function testSimpleSelectMultiOrdered() {
    */
   function testSimpleSelectOrderedDesc() {
     $query = db_select('test');
-    $name_field = $query->addField('test', 'name');
+    $query->addField('test', 'name');
     $age_field = $query->addField('test', 'age', 'age');
     $query->orderBy($age_field, 'DESC');
     $result = $query->execute();
diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/SelectTest.php b/core/modules/system/lib/Drupal/system/Tests/Database/SelectTest.php
index d9da2d6..ddb38b5 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/SelectTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/SelectTest.php
@@ -25,14 +25,9 @@ public static function getInfo() {
    */
   function testSimpleSelect() {
     $query = db_select('test');
-    $name_field = $query->addField('test', 'name');
-    $age_field = $query->addField('test', 'age', 'age');
-    $result = $query->execute();
-
-    $num_records = 0;
-    foreach ($result as $record) {
-      $num_records++;
-    }
+    $query->addField('test', 'name');
+    $query->addField('test', 'age', 'age');
+    $num_records = $query->countQuery()->execute()->fetchField();
 
     $this->assertEqual($num_records, 4, 'Returned the correct number of rows.');
   }
@@ -42,19 +37,14 @@ function testSimpleSelect() {
    */
   function testSimpleComment() {
     $query = db_select('test')->comment('Testing query comments');
-    $name_field = $query->addField('test', 'name');
-    $age_field = $query->addField('test', 'age', 'age');
-    $result = $query->execute();
-
-    $num_records = 0;
-    foreach ($result as $record) {
-      $num_records++;
-    }
+    $query->addField('test', 'name');
+    $query->addField('test', 'age', 'age');
+    $num_records = $query->countQuery()->execute()->fetchField();
 
     $query = (string)$query;
     $expected = "/* Testing query comments */ SELECT test.name AS name, test.age AS age\nFROM \n{test} test";
 
-    $this->assertEqual($num_records, 4, 'Returned the correct number of rows.');
+    $this->assertEqual($num_records, 4,  'Returned the correct number of rows.');
     $this->assertEqual($query, $expected, 'The flattened query contains the comment string.');
   }
 
@@ -63,14 +53,9 @@ function testSimpleComment() {
    */
   function testVulnerableComment() {
     $query = db_select('test')->comment('Testing query comments */ SELECT nid FROM {node}; --');
-    $name_field = $query->addField('test', 'name');
-    $age_field = $query->addField('test', 'age', 'age');
-    $result = $query->execute();
-
-    $num_records = 0;
-    foreach ($result as $record) {
-      $num_records++;
-    }
+    $query->addField('test', 'name');
+    $query->addField('test', 'age', 'age');
+    $num_records = $query->countQuery()->execute()->fetchField();
 
     $query = (string)$query;
     $expected = "/* Testing query comments SELECT nid FROM {node}; -- */ SELECT test.name AS name, test.age AS age\nFROM \n{test} test";
diff --git a/core/modules/system/lib/Drupal/system/Tests/Form/ProgrammaticTest.php b/core/modules/system/lib/Drupal/system/Tests/Form/ProgrammaticTest.php
index 6753239..b802ac3 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Form/ProgrammaticTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Form/ProgrammaticTest.php
@@ -35,7 +35,7 @@ public static function getInfo() {
   function testSubmissionWorkflow() {
     // Backup the current batch status and reset it to avoid conflicts while
     // processing the dummy form submit handler.
-    $current_batch = $batch =& batch_get();
+    $current_batch =& batch_get();
     $batch = array();
 
     // Test that a programmatic form submission is rejected when a required
diff --git a/core/modules/system/lib/Drupal/system/Tests/Lock/LockFunctionalTest.php b/core/modules/system/lib/Drupal/system/Tests/Lock/LockFunctionalTest.php
index bf868db..0fa4fb6 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Lock/LockFunctionalTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Lock/LockFunctionalTest.php
@@ -60,7 +60,6 @@ public function testLockAcquire() {
 
     // Check the shut-down function.
     $lock_acquired_exit = 'TRUE: Lock successfully acquired in system_test_lock_exit()';
-    $lock_not_acquired_exit = 'FALSE: Lock not acquired in system_test_lock_exit()';
     $this->drupalGet('system-test/lock-exit');
     $this->assertText($lock_acquired_exit, 'Lock acquired by the other request before exit.', 'Lock');
     $this->assertTrue(lock()->acquire('system_test_lock_exit'), 'Lock acquired by this request after the other request exits.', 'Lock');
diff --git a/core/modules/system/lib/Drupal/system/Tests/System/FrontPageTest.php b/core/modules/system/lib/Drupal/system/Tests/System/FrontPageTest.php
index 336c2cb..f017faf 100644
--- a/core/modules/system/lib/Drupal/system/Tests/System/FrontPageTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/System/FrontPageTest.php
@@ -52,7 +52,7 @@ public function testDrupalFrontPage() {
       'title' => $this->randomName(8),
       'promote' => 1,
     );
-    $node = $this->drupalCreateNode($settings);
+    $this->drupalCreateNode($settings);
     $this->drupalGet('');
     $this->assertTitle('Home | Drupal');