diff --git a/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php b/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php
index efb3d2f..2e0e422 100644
--- a/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php
+++ b/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php
@@ -123,7 +123,7 @@ public function testFeedPage() {
     $outline = $this->xpath('//outline[1]');
     $this->assertEqual($outline[0]['type'], 'rss', 'The correct type attribute is used for rss OPML.');
     $this->assertEqual($outline[0]['text'], $feed->label(), 'The correct text attribute is used for rss OPML.');
-    $this->assertEqual($outline[0]['xmlurl'], $feed->getUrl(), 'The correct xmlUrl attribute is used for rss OPML.');
+    $this->assertEqual($outline[0]['xmlUrl'], $feed->getUrl(), 'The correct xmlUrl attribute is used for rss OPML.');
 
     // Check for the presence of a pager.
     $this->drupalGet('aggregator/sources/' . $feed->id());
diff --git a/core/modules/comment/src/Tests/Views/RowRssTest.php b/core/modules/comment/src/Tests/Views/RowRssTest.php
index 89b9c1b..4536652 100644
--- a/core/modules/comment/src/Tests/Views/RowRssTest.php
+++ b/core/modules/comment/src/Tests/Views/RowRssTest.php
@@ -31,7 +31,7 @@ public function testRssRow() {
     $result = $this->xpath('//item');
     $this->assertEqual(count($result), 1, 'Just one comment was found in the rss output.');
 
-    $this->assertEqual($result[0]->pubdate, gmdate('r', $this->comment->getCreatedTime()), 'The right pubDate appears in the rss output.');
+    $this->assertEqual($result[0]->pubDate, gmdate('r', $this->comment->getCreatedTime()), 'The right pubDate appears in the rss output.');
   }
 
 }
diff --git a/core/modules/editor/src/Tests/QuickEditIntegrationLoadingTest.php b/core/modules/editor/src/Tests/QuickEditIntegrationLoadingTest.php
index c4b81ea..6e7316d 100644
--- a/core/modules/editor/src/Tests/QuickEditIntegrationLoadingTest.php
+++ b/core/modules/editor/src/Tests/QuickEditIntegrationLoadingTest.php
@@ -85,7 +85,10 @@ public function testUsersWithoutPermission() {
       $this->drupalGet('node/1');
 
       // Ensure the text is transformed.
-      $this->assertRaw('<p>Do you also love Drupal?</p><figure class="caption caption-img"><img src="druplicon.png" /><figcaption>Druplicon</figcaption></figure>');
+      $this->assertRaw('<p>Do you also love Drupal?</p><figure class="caption caption-img">
+<img src="druplicon.png">
+<figcaption>Druplicon</figcaption>
+</figure>');
 
       // Retrieving the untransformed text should result in an empty 403 response.
       $response = $this->drupalPost('editor/' . 'node/1/body/en/full', 'application/vnd.drupal-ajax', array());
@@ -103,7 +106,10 @@ public function testUserWithPermission() {
     $this->drupalGet('node/1');
 
     // Ensure the text is transformed.
-    $this->assertRaw('<p>Do you also love Drupal?</p><figure class="caption caption-img"><img src="druplicon.png" /><figcaption>Druplicon</figcaption></figure>');
+    $this->assertRaw('<p>Do you also love Drupal?</p><figure class="caption caption-img">
+<img src="druplicon.png">
+<figcaption>Druplicon</figcaption>
+</figure>');
 
     $response = $this->drupalPost('editor/' . 'node/1/body/en/full', 'application/vnd.drupal-ajax', array());
     $this->assertResponse(200);
diff --git a/core/modules/image/src/Tests/ImageFieldDisplayTest.php b/core/modules/image/src/Tests/ImageFieldDisplayTest.php
index b73c06f..42d71ac 100644
--- a/core/modules/image/src/Tests/ImageFieldDisplayTest.php
+++ b/core/modules/image/src/Tests/ImageFieldDisplayTest.php
@@ -290,8 +290,8 @@ function testImageFieldSettings() {
     $edit = array();
     $edit['files[' . $field_name . '_2][]'] = drupal_realpath($test_image->uri);
     $this->drupalPostAjaxForm(NULL, $edit, $field_name . '_2_upload_button');
-    $this->assertNoRaw('<input multiple type="file" id="edit-' . strtr($field_name, '_', '-') . '-2-upload" name="files[' . $field_name . '_2][]" size="22" class="form-file">');
-    $this->assertRaw('<input multiple type="file" id="edit-' . strtr($field_name, '_', '-') . '-3-upload" name="files[' . $field_name . '_3][]" size="22" class="form-file">');
+    $this->assertNoRaw('<input multiple="multiple" type="file" id="edit-' . strtr($field_name, '_', '-') . '-2-upload" name="files[' . $field_name . '_2][]" size="22" class="form-file">');
+    $this->assertRaw('<input multiple="multiple" type="file" id="edit-' . strtr($field_name, '_', '-') . '-3-upload" name="files[' . $field_name . '_3][]" size="22" class="form-file">');
   }
 
   /**
diff --git a/core/modules/rdf/src/Tests/Field/FieldRdfaTestBase.php b/core/modules/rdf/src/Tests/Field/FieldRdfaTestBase.php
index efd66eb..74e4750 100644
--- a/core/modules/rdf/src/Tests/Field/FieldRdfaTestBase.php
+++ b/core/modules/rdf/src/Tests/Field/FieldRdfaTestBase.php
@@ -7,6 +7,7 @@
 namespace Drupal\rdf\Tests\Field;
 
 use Drupal\field\Tests\FieldUnitTestBase;
+use Drupal\simpletest\XPathExpressionParser;
 use Masterminds\HTML5;
 
 abstract class FieldRdfaTestBase extends FieldUnitTestBase {
@@ -179,6 +180,14 @@ protected function parseContent($content) {
   protected function xpathContent($content, $xpath, array $arguments = array()) {
     if ($elements = $this->parseContent($content)) {
       $xpath = $this->buildXPathQuery($xpath, $arguments);
+
+      // Register the default namespace if it exists.
+      $namespaces = $elements->getDocNamespaces();
+      if (!empty($namespaces[''])) {
+        $xpath = XPathExpressionParser::rewrite($xpath);
+        $elements->registerXPathNamespace('__x__', $namespaces['']);
+      }
+
       $result = $elements->xpath($xpath);
       // Some combinations of PHP / libxml versions return an empty array
       // instead of the documented FALSE. Forcefully convert any falsish values
diff --git a/core/modules/system/src/Tests/Menu/MenuTestBase.php b/core/modules/system/src/Tests/Menu/MenuTestBase.php
index 2478af3..eb62547 100644
--- a/core/modules/system/src/Tests/Menu/MenuTestBase.php
+++ b/core/modules/system/src/Tests/Menu/MenuTestBase.php
@@ -117,7 +117,7 @@ protected function assertMenuActiveTrail($tree, $last_active) {
       $xpath .= '//';
     }
     $xpath_last_active = ($last_active ? 'and contains(@class, :class-active)' : '');
-    $xpath .= 'li[contains(@class, :class-trail)]/a[contains(@href, :href) ' . $xpath_last_active . 'and contains(text(), :title)]';
+    $xpath .= 'li[contains(@class, :class-trail)]/a[contains(@href, :href) ' . $xpath_last_active . ' and contains(text(), :title)]';
     $args = array(
       ':class-trail' => 'active-trail',
       ':class-active' => 'active',
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxesZeroForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxesZeroForm.php
index ccd752f..e7d0aa6 100644
--- a/core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxesZeroForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestCheckboxesZeroForm.php
@@ -56,7 +56,7 @@ public function buildForm(array $form, FormStateInterface $form_state, $json = T
    * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
-    if ($form_state->has('json')) {
+    if ($form_state->get('json')) {
       $form_state->setResponse(new JsonResponse($form_state->getValues()));
     }
     else {
diff --git a/core/modules/views/src/Tests/Handler/FieldWebTest.php b/core/modules/views/src/Tests/Handler/FieldWebTest.php
index e953ead..e9f65ce 100644
--- a/core/modules/views/src/Tests/Handler/FieldWebTest.php
+++ b/core/modules/views/src/Tests/Handler/FieldWebTest.php
@@ -10,6 +10,7 @@
 use Drupal\Component\Utility\Unicode;
 use Drupal\Component\Utility\String;
 use Drupal\Component\Utility\UrlHelper;
+use Drupal\simpletest\XPathExpressionParser;
 use Drupal\views\Views;
 use Masterminds\HTML5;
 
@@ -164,6 +165,14 @@ protected function parseContent($content) {
   protected function xpathContent($content, $xpath, array $arguments = array()) {
     if ($elements = $this->parseContent($content)) {
       $xpath = $this->buildXPathQuery($xpath, $arguments);
+
+      // Register the default namespace if it exists.
+      $namespaces = $elements->getDocNamespaces();
+      if (!empty($namespaces[''])) {
+        $xpath = XPathExpressionParser::rewrite($xpath);
+        $elements->registerXPathNamespace('__x__', $namespaces['']);
+      }
+
       $result = $elements->xpath($xpath);
       // Some combinations of PHP / libxml versions return an empty array
       // instead of the documented FALSE. Forcefully convert any falsish values