diff --git a/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
index 944810a..5c2319a 100644
--- a/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -5,6 +5,7 @@
 use Drupal\Component\Assertion\Handle;
 use Drupal\Component\Render\MarkupInterface;
 use Drupal\Component\Utility\Crypt;
+use Drupal\Component\Utility\Random;
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Database\Database;
 use Drupal\Core\Site\Settings;
@@ -12,8 +13,7 @@
 use Drupal\Core\Test\TestDatabase;
 use Drupal\Core\Utility\Error;
 use Drupal\Tests\ConfigTestTrait;
-use Drupal\Tests\RandomGeneratorTrait;
-use Drupal\Tests\SessionTestTrait;
+use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Base class for Drupal tests.
@@ -22,9 +22,6 @@
  */
 abstract class TestBase {
 
-  use SessionTestTrait;
-  use RandomGeneratorTrait;
-  use AssertHelperTrait;
   // For backwards compatibility switch the visbility of the methods to public.
   use ConfigTestTrait {
     configImporter as public;
@@ -58,6 +55,20 @@
   protected $timeLimit = 500;
 
   /**
+   * The name of the session cookie.
+   *
+   * @var string
+   */
+  protected $sessionName;
+
+  /**
+   * The random generator.
+   *
+   * @var \Drupal\Component\Utility\Random
+   */
+  protected $randomGenerator;
+
+  /**
    * Current results of this test case.
    *
    * @var Array
@@ -1592,4 +1603,159 @@ protected function getConfigSchemaExclusions() {
     return array_unique($exceptions);
   }
 
+  /**
+   * Generates a session cookie name.
+   *
+   * @param string $data
+   *   The data to generate session name.
+   */
+  protected function generateSessionName($data) {
+    $prefix = (Request::createFromGlobals()->isSecure() ? 'SSESS' : 'SESS');
+    $this->sessionName = $prefix . substr(hash('sha256', $data), 0, 32);
+  }
+
+  /**
+   * Returns the session name in use on the child site.
+   *
+   * @return string
+   *   The name of the session cookie.
+   */
+  protected function getSessionName() {
+    return $this->sessionName;
+  }
+
+  /**
+   * Generates a pseudo-random string of ASCII characters of codes 32 to 126.
+   *
+   * Do not use this method when special characters are not possible (e.g., in
+   * machine or file names that have already been validated); instead, use
+   * \Drupal\simpletest\TestBase::randomMachineName(). If $length is greater
+   * than 3 the random string will include at least one ampersand ('&') and
+   * at least one greater than ('>') character to ensure coverage for special
+   * characters and avoid the introduction of random test failures.
+   *
+   * @param int $length
+   *   Length of random string to generate.
+   *
+   * @return string
+   *   Pseudo-randomly generated unique string including special characters.
+   *
+   * @see \Drupal\Component\Utility\Random::string()
+   */
+  public function randomString($length = 8) {
+    if ($length < 4) {
+      return $this->getRandomGenerator()->string($length, TRUE, array(
+        $this,
+        'randomStringValidate',
+      ));
+    }
+
+    // To prevent the introduction of random test failures, ensure that the
+    // returned string contains a character that needs to be escaped in HTML by
+    // injecting an ampersand into it.
+    $replacement_pos = floor($length / 2);
+    // Remove 2 from the length to account for the ampersand and greater than
+    // characters.
+    $string = $this->getRandomGenerator()
+      ->string($length - 2, TRUE, array($this, 'randomStringValidate'));
+    return substr_replace($string, '>&', $replacement_pos, 0);
+  }
+
+  /**
+   * Callback for random string validation.
+   *
+   * @param string $string
+   *   The random string to validate.
+   *
+   * @see \Drupal\Component\Utility\Random::string()
+   *
+   * @return bool
+   *   TRUE if the random string is valid, FALSE if not.
+   */
+  public function randomStringValidate($string) {
+    // Consecutive spaces causes issues for
+    // \Drupal\simpletest\WebTestBase::assertLink().
+    if (preg_match('/\s{2,}/', $string)) {
+      return FALSE;
+    }
+
+    // Starting or ending with a space means that length might not be what is
+    // expected.
+    if (preg_match('/^\s|\s$/', $string)) {
+      return FALSE;
+    }
+
+    return TRUE;
+  }
+
+  /**
+   * Generates a unique random string containing letters and numbers.
+   *
+   * Do not use this method when testing unvalidated user input. Instead, use
+   * \Drupal\simpletest\TestBase::randomString().
+   *
+   * @param int $length
+   *   Length of random string to generate.
+   *
+   * @return string
+   *   Randomly generated unique string.
+   *
+   * @see \Drupal\Component\Utility\Random::name()
+   */
+  protected function randomMachineName($length = 8) {
+    return $this->getRandomGenerator()->name($length, TRUE);
+  }
+
+  /**
+   * Generates a random PHP object.
+   *
+   * @param int $size
+   *   The number of random keys to add to the object.
+   *
+   * @return \stdClass
+   *   The generated object, with the specified number of random keys. Each key
+   *   has a random string value.
+   *
+   * @see \Drupal\Component\Utility\Random::object()
+   */
+  public function randomObject($size = 4) {
+    return $this->getRandomGenerator()->object($size);
+  }
+
+  /**
+   * Gets the random generator for the utility methods.
+   *
+   * @return \Drupal\Component\Utility\Random
+   *   The random generator.
+   */
+  protected function getRandomGenerator() {
+    if (!is_object($this->randomGenerator)) {
+      $this->randomGenerator = new Random();
+    }
+    return $this->randomGenerator;
+  }
+
+  /**
+   * Casts MarkupInterface objects into strings.
+   *
+   * @param string|array $value
+   *   The value to act on.
+   *
+   * @return mixed
+   *   The input value, with MarkupInterface objects casted to string.
+   */
+  protected static function castSafeStrings($value) {
+    if ($value instanceof MarkupInterface) {
+      $value = (string) $value;
+    }
+    if (is_array($value)) {
+      array_walk_recursive($value, function (&$item) {
+        if ($item instanceof MarkupInterface) {
+          $item = (string) $item;
+        }
+      });
+    }
+    return $value;
+  }
+
 }