diff --git a/core/composer.json b/core/composer.json
index 26938e3..5e80a3f 100644
--- a/core/composer.json
+++ b/core/composer.json
@@ -3,6 +3,8 @@
   "description": "Drupal is an open source content management platform powering millions of websites and applications.",
   "type": "drupal-core",
   "license": "GPL-2.0+",
+  "minimum-stability": "dev",
+  "prefer-stable": true,
   "require": {
     "php": ">=5.5.9",
     "symfony/class-loader": "2.7.*",
@@ -30,6 +32,7 @@
     "stack/builder": "1.0.*",
     "egulias/email-validator": "1.2.*",
     "behat/mink": "~1.6",
+    "symfony/phpunit-bridge": "^3.0@dev"
     "behat/mink-goutte-driver": "dev-master#cc5ce119b5a8e06662f634b35967aff0b0c7dfdd",
     "fabpot/goutte": "~3.1",
     "masterminds/html5": "~2.1",
diff --git a/core/composer.lock b/core/composer.lock
index 676d0bf..888b1ac 100644
--- a/core/composer.lock
+++ b/core/composer.lock
@@ -2695,6 +2695,58 @@
             "time": "2015-07-13 19:27:49"
         },
         {
+            "name": "symfony/phpunit-bridge",
+            "version": "dev-master",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/phpunit-bridge.git",
+                "reference": "242cbb7b4cb7b15c4987a59e85543bdfa8a4c720"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/phpunit-bridge/zipball/242cbb7b4cb7b15c4987a59e85543bdfa8a4c720",
+                "reference": "242cbb7b4cb7b15c4987a59e85543bdfa8a4c720",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.5.9"
+            },
+            "suggest": {
+                "symfony/debug": "For tracking deprecated interfaces usages at runtime with DebugClassLoader"
+            },
+            "type": "symfony-bridge",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.0-dev"
+                }
+            },
+            "autoload": {
+                "files": [
+                    "bootstrap.php"
+                ],
+                "psr-4": {
+                    "Symfony\\Bridge\\PhpUnit\\": ""
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony PHPUnit Bridge",
+            "homepage": "https://symfony.com",
+            "time": "2015-05-12 15:48:43"
+        },
+        {
             "name": "symfony/process",
             "version": "v2.7.2",
             "source": {
@@ -3370,6 +3422,8 @@
     "aliases": [],
     "minimum-stability": "dev",
     "stability-flags": {
+        "symfony/validator": 20,
+        "symfony/phpunit-bridge": 20
         "guzzlehttp/guzzle": 20,
         "behat/mink-goutte-driver": 20
     },
diff --git a/core/phpunit.xml.dist b/core/phpunit.xml.dist
index 743bf08..f23d50d 100644
--- a/core/phpunit.xml.dist
+++ b/core/phpunit.xml.dist
@@ -10,6 +10,7 @@
     <!-- Example SIMPLETEST_BASE_URL value: http://localhost -->
     <env name="SIMPLETEST_DB" value=""/>
     <!-- Example SIMPLETEST_DB value: mysql://username:password@localhost/databasename#table_prefix -->
+    <ini name="error_reporting" value="-1" />
   </php>
   <testsuites>
     <testsuite name="unit">
diff --git a/core/tests/bootstrap.php b/core/tests/bootstrap.php
index fd980a4..a4114ed 100644
--- a/core/tests/bootstrap.php
+++ b/core/tests/bootstrap.php
@@ -6,6 +6,7 @@
  *
  * @see phpunit.xml.dist
  */
+use Symfony\Bridge\PhpUnit\DeprecationErrorHandler;
 
 /**
  * Finds all valid extension directories recursively within a given directory.
@@ -89,3 +90,5 @@ function drupal_phpunit_register_extension_dirs(Composer\Autoload\ClassLoader $l
 // Set the default timezone. While this doesn't cause any tests to fail, PHP
 // complains if 'date.timezone' is not set in php.ini.
 date_default_timezone_set('UTC');
+
+DeprecationErrorHandler::register();
diff --git a/core/vendor/composer/autoload_files.php b/core/vendor/composer/autoload_files.php
index 6f932aa..9d09c48 100644
--- a/core/vendor/composer/autoload_files.php
+++ b/core/vendor/composer/autoload_files.php
@@ -6,6 +6,8 @@
 $baseDir = dirname($vendorDir);
 
 return array(
+    $vendorDir . '/symfony/phpunit-bridge/bootstrap.php',
+    $vendorDir . '/react/promise/src/functions_include.php',
     $vendorDir . '/guzzlehttp/psr7/src/functions.php',
     $vendorDir . '/guzzlehttp/promises/src/functions.php',
     $vendorDir . '/guzzlehttp/guzzle/src/functions_include.php',
diff --git a/core/vendor/composer/autoload_psr4.php b/core/vendor/composer/autoload_psr4.php
index aeaabc1..cbd5c0c 100644
--- a/core/vendor/composer/autoload_psr4.php
+++ b/core/vendor/composer/autoload_psr4.php
@@ -27,6 +27,8 @@
     'Symfony\\Component\\ClassLoader\\' => array($vendorDir . '/symfony/class-loader'),
     'Symfony\\Component\\BrowserKit\\' => array($vendorDir . '/symfony/browser-kit'),
     'Symfony\\Cmf\\Component\\Routing\\' => array($vendorDir . '/symfony-cmf/routing'),
+    'Symfony\\Bridge\\PhpUnit\\' => array($vendorDir . '/symfony/phpunit-bridge'),
+    'React\\Promise\\' => array($vendorDir . '/react/promise/src'),
     'Symfony\\Bridge\\PsrHttpMessage\\' => array($vendorDir . '/symfony/psr-http-message-bridge'),
     'Psr\\Http\\Message\\' => array($vendorDir . '/psr/http-message/src'),
     'Masterminds\\' => array($vendorDir . '/masterminds/html5/src'),
diff --git a/core/vendor/composer/installed.json b/core/vendor/composer/installed.json
index e063543..18a09b6 100644
--- a/core/vendor/composer/installed.json
+++ b/core/vendor/composer/installed.json
@@ -3477,5 +3477,59 @@
             "validation",
             "validator"
         ]
+    },
+    {
+        "name": "symfony/phpunit-bridge",
+        "version": "dev-master",
+        "version_normalized": "9999999-dev",
+        "source": {
+            "type": "git",
+            "url": "https://github.com/symfony/phpunit-bridge.git",
+            "reference": "242cbb7b4cb7b15c4987a59e85543bdfa8a4c720"
+        },
+        "dist": {
+            "type": "zip",
+            "url": "https://api.github.com/repos/symfony/phpunit-bridge/zipball/242cbb7b4cb7b15c4987a59e85543bdfa8a4c720",
+            "reference": "242cbb7b4cb7b15c4987a59e85543bdfa8a4c720",
+            "shasum": ""
+        },
+        "require": {
+            "php": ">=5.5.9"
+        },
+        "suggest": {
+            "symfony/debug": "For tracking deprecated interfaces usages at runtime with DebugClassLoader"
+        },
+        "time": "2015-05-12 15:48:43",
+        "type": "symfony-bridge",
+        "extra": {
+            "branch-alias": {
+                "dev-master": "3.0-dev"
+            }
+        },
+        "installation-source": "source",
+        "autoload": {
+            "files": [
+                "bootstrap.php"
+            ],
+            "psr-4": {
+                "Symfony\\Bridge\\PhpUnit\\": ""
+            }
+        },
+        "notification-url": "https://packagist.org/downloads/",
+        "license": [
+            "MIT"
+        ],
+        "authors": [
+            {
+                "name": "Nicolas Grekas",
+                "email": "p@tchwork.com"
+            },
+            {
+                "name": "Symfony Community",
+                "homepage": "https://symfony.com/contributors"
+            }
+        ],
+        "description": "Symfony PHPUnit Bridge",
+        "homepage": "https://symfony.com"
     }
 ]