diff --git a/spec/Drupal/Driver/Cores/Drupal8Spec.php b/spec/Drupal/Driver/Cores/Drupal8Spec.php
index b3732651..a73162e5 100644
--- a/spec/Drupal/Driver/Cores/Drupal8Spec.php
+++ b/spec/Drupal/Driver/Cores/Drupal8Spec.php
@@ -18,4 +18,9 @@ function it_is_initializable()
     {
         $this->shouldHaveType('Drupal\Driver\Cores\Drupal8');
     }
+
+    function it_should_return_a_random_generator()
+    {
+        $this->getRandom()->shouldBeAnInstanceOf('Drupal\Component\Utility\Random');
+    }
 }
diff --git a/src/Drupal/Driver/Cores/AbstractCore.php b/src/Drupal/Driver/Cores/AbstractCore.php
index baae4c76..3a381001 100644
--- a/src/Drupal/Driver/Cores/AbstractCore.php
+++ b/src/Drupal/Driver/Cores/AbstractCore.php
@@ -7,10 +7,51 @@
 
 namespace Drupal\Driver\Cores;
 
+use Drupal\Component\Utility\Random;
 use Symfony\Component\DependencyInjection\Container;
 
 abstract class AbstractCore implements CoreInterface {
 
+  /**
+   * System path to the Drupal installation.
+   *
+   * @var string
+   */
+  private $drupalRoot;
+
+  /**
+   * URI for the Drupal installation.
+   *
+   * @var string
+   */
+  private $uri;
+
+  /**
+   * Random generator.
+   *
+   * @var \Drupal\Component\Utility\Random
+   */
+  private $random;
+
+  /**
+   * {@inheritDoc}
+   */
+  public function __construct($drupalRoot, $uri = 'default', Random $random = NULL) {
+    $this->drupalRoot = realpath($drupalRoot);
+    $this->uri = $uri;
+    if (!isset($random)) {
+      $random = new Random();
+    }
+    $this->random = $random;
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  public function getRandom() {
+    return $this->random;
+  }
+
   /**
    * {@inheritDoc}
    */
diff --git a/src/Drupal/Driver/Cores/CoreInterface.php b/src/Drupal/Driver/Cores/CoreInterface.php
index e4bffde7..e083adbb 100644
--- a/src/Drupal/Driver/Cores/CoreInterface.php
+++ b/src/Drupal/Driver/Cores/CoreInterface.php
@@ -8,6 +8,7 @@
  * Drupal core interface.
  */
 interface CoreInterface {
+
   /**
    * Instantiate the core interface.
    *
@@ -19,7 +20,7 @@ interface CoreInterface {
    * @param \Drupal\Component\Utility\Random $random
    *   Random string generator.
    */
-  public function __construct($drupalRoot, $uri = 'default', Random $random);
+  public function __construct($drupalRoot, $uri = 'default', Random $random = NULL);
 
   /**
    * Return random generator.
diff --git a/src/Drupal/Driver/Cores/Drupal7.php b/src/Drupal/Driver/Cores/Drupal7.php
index c9112a69..37b4fa8d 100644
--- a/src/Drupal/Driver/Cores/Drupal7.php
+++ b/src/Drupal/Driver/Cores/Drupal7.php
@@ -4,51 +4,11 @@
 
 use Drupal\Component\Utility\Random;
 use Drupal\Driver\Exception\BootstrapException;
-use Symfony\Component\DependencyInjection\Container;
 
 /**
  * Drupal 7 core.
  */
 class Drupal7 extends AbstractCore {
-  /**
-   * System path to the Drupal installation.
-   *
-   * @var string
-   */
-  private $drupalRoot;
-
-  /**
-   * URI for the Drupal installation.
-   *
-   * @var string
-   */
-  private $uri;
-
-  /**
-   * Random generator.
-   *
-   * @var \Drupal\Component\Utility\Random
-   */
-  private $random;
-
-  /**
-   * {@inheritDoc}
-   */
-  public function __construct($drupalRoot, $uri = 'default', Random $random = NULL) {
-    $this->drupalRoot = realpath($drupalRoot);
-    $this->uri = $uri;
-    if (!isset($random)) {
-      $random = new Random();
-    }
-    $this->random = $random;
-  }
-
-  /**
-   * {@inheritDoc}
-   */
-  public function getRandom() {
-    return $this->random;
-  }
 
   /**
    * {@inheritDoc}
diff --git a/src/Drupal/Driver/Cores/Drupal8.php b/src/Drupal/Driver/Cores/Drupal8.php
index 2eb4c02e..74a1f4e9 100644
--- a/src/Drupal/Driver/Cores/Drupal8.php
+++ b/src/Drupal/Driver/Cores/Drupal8.php
@@ -13,45 +13,6 @@
  * Drupal 8 core.
  */
 class Drupal8 extends AbstractCore {
-  /**
-   * System path to the Drupal installation.
-   *
-   * @var string
-   */
-  private $drupalRoot;
-
-  /**
-   * URI for the Drupal installation.
-   *
-   * @var string
-   */
-  private $uri;
-
-  /**
-   * Random generator.
-   *
-   * @var \Drupal\Component\Utility\Random
-   */
-  private $random;
-
-  /**
-   * {@inheritDoc}
-   */
-  public function __construct($drupalRoot, $uri = 'default', Random $random = NULL) {
-    $this->drupalRoot = realpath($drupalRoot);
-    $this->uri = $uri;
-    if (!isset($random)) {
-      $random = new Random();
-    }
-    $this->random = $random;
-  }
-
-  /**
-   * {@inheritDoc}
-   */
-  public function getRandom() {
-    return $this->random;
-  }
 
   /**
    * {@inheritDoc}