diff --git a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
index 794054d..ca3abf6 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -91,6 +91,36 @@ abstract class TestBase {
   protected $setupEnvironment = FALSE;
 
   /**
+   * TRUE if verbose debugging is enabled.
+   *
+   * @var boolean
+   */
+  protected $verbose = FALSE;
+
+  /**
+   * Incrementing identifier for verbose output filenames.
+   *
+   * @var integer
+   */
+  protected $verboseId = 0;
+
+  /**
+   * Safe class name for use in verbose output filenames.
+   *
+   * Namespaces separator (\) replaced with _.
+   *
+   * @var string
+   */
+  protected $verboseClassName;
+
+  /**
+   * Directory where verbose output files are put.
+   *
+   * @var string
+   */
+  protected $verboseDirectory;
+
+  /**
    * Constructor for Test.
    *
    * @param $test_id
@@ -457,11 +487,21 @@ abstract class TestBase {
    * @see simpletest_verbose()
    */
   protected function verbose($message) {
-    if ($id = simpletest_verbose($message)) {
-      $class = str_replace('\\', '_', get_class($this));
-      $url = file_create_url($this->originalFileDirectory . '/simpletest/verbose/' . $class . '-' . $id . '.html');
-      $this->error(l(t('Verbose message'), $url, array('attributes' => array('target' => '_blank'))), 'User notice');
+    // Do nothing if verbose debugging is disabled.
+    if (!$this->verbose) {
+      return;
+    }
+
+    $message = '<hr />ID #' . $this->verboseId . ' (<a href="' . $this->verboseClassName . '-' . ($this->verboseId - 1) . '.html">Previous</a> | <a href="' . $this->verboseClassName . '-' . ($this->verboseId + 1) . '.html">Next</a>)<hr />' . $message;
+    $verbose_filename = $this->verboseDirectory . '/' . $this->verboseClassName . '-' . $this->verboseId . '.html';
+    if (file_put_contents($verbose_filename, $message, FILE_APPEND)) {
+      $url = file_create_url($this->originalFileDirectory . '/simpletest/verbose/' . $this->verboseClassName . '-' . $this->verboseId . '.html');
+      // Not using l() to avoid invoking the theme system, so that unit tests
+      // can use verbose() as well.
+      $url = '<a href="' . $url . '" target="_blank">' . t('Verbose message') . '</a>';
+      $this->error($url, 'User notice');
     }
+    $this->verboseId++;
   }
 
   /**
@@ -477,10 +517,16 @@ abstract class TestBase {
    *   methods during debugging.
    */
   public function run(array $methods = array()) {
-    // Initialize verbose debugging.
     $class = get_class($this);
-    simpletest_verbose(NULL, variable_get('file_public_path', conf_path() . '/files'), str_replace('\\', '_', $class));
-
+    if (variable_get('simpletest_verbose', TRUE)) {
+      // Initialize verbose debugging.
+      $this->verbose = TRUE;
+      $this->verboseDirectory = variable_get('file_public_path', conf_path() . '/files') . '/simpletest/verbose';
+      if (file_prepare_directory($this->verboseDirectory, FILE_CREATE_DIRECTORY) && !file_exists($this->verboseDirectory . '/.htaccess')) {
+        file_put_contents($this->verboseDirectory . '/.htaccess', "<IfModule mod_expires.c>\nExpiresActive Off\n</IfModule>\n");
+      }
+      $this->verboseClassName = str_replace("\\", "_", $class);
+    }
     // HTTP auth settings (<username>:<password>) for the simpletest browser
     // when sending requests to the test site.
     $this->httpauth_method = variable_get('simpletest_httpauth_method', CURLAUTH_BASIC);
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
index d54912a..98ed71d 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
@@ -55,12 +55,6 @@ abstract class UnitTestBase extends TestBase {
     // Enforce an empty module list.
     module_list(NULL, array());
 
-    // Re-implant theme registry.
-    // Required for l() and other functions to work correctly and not trigger
-    // database lookups.
-    $theme_get_registry = &drupal_static('theme_get_registry');
-    $theme_get_registry[FALSE] = $this->originalThemeRegistry;
-
     $conf['file_public_path'] = $this->public_files_directory;
 
     // Change the database prefix.
diff --git a/core/modules/simpletest/simpletest.module b/core/modules/simpletest/simpletest.module
index 38c360b..4138916 100644
--- a/core/modules/simpletest/simpletest.module
+++ b/core/modules/simpletest/simpletest.module
@@ -566,51 +566,3 @@ function simpletest_mail_alter(&$message) {
     $message['send'] = FALSE;
   }
 }
-
-/**
- * Logs verbose message in a text file.
- *
- * If verbose mode is enabled then page requests will be dumped to a file and
- * presented on the test result screen. The messages will be placed in a file
- * located in the simpletest directory in the original file system.
- *
- * @param $message
- *   The verbose message to be stored.
- * @param $original_file_directory
- *   The original file directory, before it was changed for testing purposes.
- * @param $test_class
- *   The active test case class.
- *
- * @return
- *   The ID of the message to be placed in related assertion messages.
- *
- * @see Drupal\simpletest\TestBase->originalFileDirectory()
- * @see Drupal\simpletest\WebTestBase->verbose()
- */
-function simpletest_verbose($message, $original_file_directory = NULL, $test_class = NULL) {
-  static $file_directory = NULL, $class = NULL, $id = 1, $verbose = NULL;
-
-  // Will pass first time during setup phase, and when verbose is TRUE.
-  if (!isset($original_file_directory) && !$verbose) {
-    return FALSE;
-  }
-
-  if ($message && $file_directory) {
-    $message = '<hr />ID #' . $id . ' (<a href="' . $class . '-' . ($id - 1) . '.html">Previous</a> | <a href="' . $class . '-' . ($id + 1) . '.html">Next</a>)<hr />' . $message;
-    file_put_contents($file_directory . "/simpletest/verbose/$class-$id.html", $message, FILE_APPEND);
-    return $id++;
-  }
-
-  if ($original_file_directory) {
-    $file_directory = $original_file_directory;
-    $class = $test_class;
-    $verbose = variable_get('simpletest_verbose', TRUE);
-    $directory = $file_directory . '/simpletest/verbose';
-    $writable = file_prepare_directory($directory, FILE_CREATE_DIRECTORY);
-    if ($writable && !file_exists($directory . '/.htaccess')) {
-      file_put_contents($directory . '/.htaccess', "<IfModule mod_expires.c>\nExpiresActive Off\n</IfModule>\n");
-    }
-    return $writable;
-  }
-  return FALSE;
-}