diff --git a/core/includes/common.inc b/core/includes/common.inc
index 667807a..d59161d 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -1,6 +1,7 @@
 <?php
 
 use Drupal\Component\Utility\Crypt;
+use Drupal\Component\Utility\Json;
 use Drupal\Component\Utility\String;
 use Drupal\Component\Utility\Tags;
 use Drupal\Component\Utility\UrlValidator;
@@ -3989,10 +3990,11 @@ function drupal_clear_js_cache() {
  *
  * @see drupal_json_decode()
  * @ingroup php_wrappers
+ * @deprecated as of Drupal 8.0. Use Drupal\Component\Utility\Json::encode()
+ *   directly instead.
  */
 function drupal_json_encode($var) {
-  // Encode <, >, ', &, and " using the json_encode() options parameter.
-  return json_encode($var, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT);
+  return Json::encode($var);
 }
 
 /**
@@ -4000,9 +4002,11 @@ function drupal_json_encode($var) {
  *
  * @see drupal_json_encode()
  * @ingroup php_wrappers
+ * @deprecated as of Drupal 8.0. Use Drupal\Component\Utility\Json::decode()
+ *   directly instead.
  */
 function drupal_json_decode($var) {
-  return json_decode($var, TRUE);
+  return Json::decode($var);
 }
 
 /**
diff --git a/core/lib/Drupal/Component/Utility/Json.php b/core/lib/Drupal/Component/Utility/Json.php
new file mode 100644
index 0000000..54614b5
--- /dev/null
+++ b/core/lib/Drupal/Component/Utility/Json.php
@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Utility\Json.
+ */
+
+namespace Drupal\Component\Utility;
+
+/**
+ * Provides helpers for dealing with json.
+ */
+class Json {
+
+  /**
+   * Converts a PHP variable into its JavaScript equivalent.
+   *
+   * We use HTML-safe strings, with several characters escaped.
+   *
+   * @param mixed $variable
+   *   The variable to encode.
+   *
+   * @return string
+   *   Returns the encoded variable.
+   *
+   * @see drupal_json_decode()
+   * @ingroup php_wrappers
+   */
+  public static function encode($variable) {
+    // Encode <, >, ', &, and " using the json_encode() options parameter.
+    return json_encode($variable, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT);
+  }
+
+  /**
+   * Converts an HTML-safe JSON string into its PHP equivalent.
+   *
+   * @param string $string
+   *   The string to decode.
+   *
+   * @return mixed
+   *   Returns the decoded string.
+   *
+   * @see drupal_json_encode()
+   * @ingroup php_wrappers
+   */
+  public static function decode($string) {
+    return json_decode($string, TRUE);
+  }
+
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/JsonUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/JsonUnitTest.php
deleted file mode 100644
index 3e771e4..0000000
--- a/core/modules/system/lib/Drupal/system/Tests/Common/JsonUnitTest.php
+++ /dev/null
@@ -1,74 +0,0 @@
-<?php
-
-/**
- * @file
- * Definition of Drupal\system\Tests\Common\JsonUnitTest.
- */
-
-namespace Drupal\system\Tests\Common;
-
-use Drupal\simpletest\UnitTestBase;
-
-/**
- * Tests the drupal_json_encode() and drupal_json_decode() functions.
- */
-class JsonUnitTest extends UnitTestBase {
-  public static function getInfo() {
-    return array(
-      'name' => 'JSON',
-      'description' => 'Tests the drupal_json_encode() and drupal_json_decode() functions to convert PHP variables to JSON strings and back.',
-      'group' => 'Common',
-    );
-  }
-
-  /**
-   * Tests converting PHP variables to JSON strings and back.
-   */
-  function testJSON() {
-    // Setup a string with the full ASCII table.
-    // @todo: Add tests for non-ASCII characters and Unicode.
-    $str = '';
-    for ($i=0; $i < 128; $i++) {
-      $str .= chr($i);
-    }
-    // Characters that must be escaped.
-    // We check for unescaped " separately.
-    $html_unsafe = array('<', '>', '\'', '&');
-    // The following are the encoded forms of: < > ' & "
-    $html_unsafe_escaped = array('\u003C', '\u003E', '\u0027', '\u0026', '\u0022');
-
-    // Verify there aren't character encoding problems with the source string.
-    $this->assertIdentical(strlen($str), 128, 'A string with the full ASCII table has the correct length.');
-    foreach ($html_unsafe as $char) {
-      $this->assertTrue(strpos($str, $char) > 0, format_string('A string with the full ASCII table includes @s.', array('@s' => $char)));
-    }
-
-    // Verify that JSON encoding produces a string with all of the characters.
-    $json = drupal_json_encode($str);
-    $this->assertTrue(strlen($json) > strlen($str), 'A JSON encoded string is larger than the source string.');
-
-    // The first and last characters should be ", and no others.
-    $this->assertTrue($json[0] == '"', 'A JSON encoded string begins with ".');
-    $this->assertTrue($json[strlen($json) - 1] == '"', 'A JSON encoded string ends with ".');
-    $this->assertTrue(substr_count($json, '"') == 2, 'A JSON encoded string contains exactly two ".');
-
-    // Verify that encoding/decoding is reversible.
-    $json_decoded = drupal_json_decode($json);
-    $this->assertIdentical($str, $json_decoded, 'Encoding a string to JSON and decoding back results in the original string.');
-
-    // Verify reversibility for structured data. Also verify that necessary
-    // characters are escaped.
-    $source = array(TRUE, FALSE, 0, 1, '0', '1', $str, array('key1' => $str, 'key2' => array('nested' => TRUE)));
-    $json = drupal_json_encode($source);
-    foreach ($html_unsafe as $char) {
-      $this->assertTrue(strpos($json, $char) === FALSE, format_string('A JSON encoded string does not contain @s.', array('@s' => $char)));
-    }
-    // Verify that JSON encoding escapes the HTML unsafe characters
-    foreach ($html_unsafe_escaped as $char) {
-      $this->assertTrue(strpos($json, $char) > 0, format_string('A JSON encoded string contains @s.', array('@s' => $char)));
-    }
-    $json_decoded = drupal_json_decode($json);
-    $this->assertNotIdentical($source, $json, 'An array encoded in JSON is not identical to the source.');
-    $this->assertIdentical($source, $json_decoded, 'Encoding structured data to JSON and decoding back results in the original data.');
-  }
-}
diff --git a/core/tests/Drupal/Tests/Component/Utility/JsonTest.php b/core/tests/Drupal/Tests/Component/Utility/JsonTest.php
new file mode 100644
index 0000000..e14fc7c
--- /dev/null
+++ b/core/tests/Drupal/Tests/Component/Utility/JsonTest.php
@@ -0,0 +1,131 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Component\Utility\JsonTest.
+ */
+
+namespace Drupal\Tests\Component\Utility;
+
+use Drupal\Component\Utility\Json;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Tests the Json::encode() and Json::decode() functions.
+ *
+ * @see \Drupal\Component\Utility\Json
+ */
+class JsonTest extends UnitTestCase {
+
+  /**
+   * A test string with the full ASCII table.
+   *
+   * @var string
+   */
+  protected $string;
+
+  /**
+   * An array of unsafe html characters which has to be encoded.
+   *
+   * @var array
+   */
+  protected $htmlUnsafe;
+
+  /**
+   * An array of unsafe html characters which are already escaped.
+   *
+   * @var array
+   */
+  protected $htmlUnsafeEscaped;
+
+
+  public static function getInfo() {
+    return array(
+      'name' => 'JSON',
+      'description' => 'Tests the Json::encode() and Json::decode() functions to convert PHP variables to JSON strings and back.',
+      'group' => 'Common',
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    // Setup a string with the full ASCII table.
+    // @todo: Add tests for non-ASCII characters and Unicode.
+    $this->string = '';
+    for ($i=0; $i < 128; $i++) {
+      $this->string .= chr($i);
+    }
+
+    // Characters that must be escaped.
+    // We check for unescaped " separately.
+    $this->htmlUnsafe = array('<', '>', '\'', '&');
+    // The following are the encoded forms of: < > ' & "
+    $this->htmlUnsafeEscaped = array('\u003C', '\u003E', '\u0027', '\u0026', '\u0022');
+  }
+
+  /**
+   * Tests encoding for every ASCII character.
+   */
+  public function testEncodingAscii() {
+    // Verify there aren't character encoding problems with the source string.
+    $this->assertSame(strlen($this->string), 128, 'A string with the full ASCII table has the correct length.');
+    foreach ($this->htmlUnsafe as $char) {
+      $this->assertTrue(strpos($this->string, $char) > 0, sprintf('A string with the full ASCII table includes %s.', $char));
+    }
+  }
+
+  /**
+   * Tests encoding length.
+   */
+  public function testEncodingLength() {
+    // Verify that JSON encoding produces a string with all of the characters.
+    $json = Json::encode($this->string);
+    $this->assertTrue(strlen($json) > strlen($this->string), 'A JSON encoded string is larger than the source string.');
+  }
+
+  /**
+   * Tests end and start of the encoded string.
+   */
+  public function testEncodingStartEnd() {
+    $json = Json::encode($this->string);
+    // The first and last characters should be ", and no others.
+    $this->assertTrue($json[0] == '"', 'A JSON encoded string begins with ".');
+    $this->assertTrue($json[strlen($json) - 1] == '"', 'A JSON encoded string ends with ".');
+    $this->assertTrue(substr_count($json, '"') == 2, 'A JSON encoded string contains exactly two ".');
+  }
+
+  /**
+   * Tests converting PHP variables to JSON strings and back.
+   */
+  public function testReversibility() {
+    $json = Json::encode($this->string);
+    // Verify that encoding/decoding is reversible.
+    $json_decoded = Json::decode($json);
+    $this->assertSame($this->string, $json_decoded, 'Encoding a string to JSON and decoding back results in the original string.');
+  }
+
+  /**
+   * Test the reversibility of structured data
+   */
+  public function testStructuredReversibility() {
+    // Verify reversibility for structured data. Also verify that necessary
+    // characters are escaped.
+    $source = array(TRUE, FALSE, 0, 1, '0', '1', $this->string, array('key1' => $this->string, 'key2' => array('nested' => TRUE)));
+    $json = Json::encode($source);
+    foreach ($this->htmlUnsafe as $char) {
+      $this->assertTrue(strpos($json, $char) === FALSE, sprintf('A JSON encoded string does not contain %s.', $char));
+    }
+    // Verify that JSON encoding escapes the HTML unsafe characters
+    foreach ($this->htmlUnsafeEscaped as $char) {
+      $this->assertTrue(strpos($json, $char) > 0, sprintf('A JSON encoded string contains %s.', $char));
+    }
+    $json_decoded = Json::decode($json);
+    $this->assertNotSame($source, $json, 'An array encoded in JSON is identical to the source.');
+    $this->assertSame($source, $json_decoded, 'Encoding structured data to JSON and decoding back not results in the original data.');
+  }
+
+}
diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index 8e081fd..ab85646 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -289,9 +289,6 @@
  * When debugging is enabled:
  * - The markup of each Twig template is surrounded by HTML comments that
  *   contain theming information, such as template file name suggestions.
- * - Note that this debugging markup will cause automated tests that directly
- *   check rendered HTML to fail. When running automated tests, 'twig_debug'
- *   should be set to FALSE.
  * - The dump() function can be used in Twig templates to output information
  *   about template variables.
  * - Twig templates are automatically recompiled whenever the source code