diff --git a/core/modules/image/src/Tests/ImageFieldTestBase.php b/core/modules/image/src/Tests/ImageFieldTestBase.php
index e69f4884e2..b144ff647a 100644
--- a/core/modules/image/src/Tests/ImageFieldTestBase.php
+++ b/core/modules/image/src/Tests/ImageFieldTestBase.php
@@ -1,7 +1,8 @@
 <?php
 
 namespace Drupal\image\Tests;
-@trigger_error(__FILE__ . ' is deprecated in Drupal 8.3.0 and will be removed before Drupal 9.0.0. Use \Drupal\Tests\image\Functional\ImageFieldTestBase instead. See https://www.drupal.org/node/2863626.', E_USER_DEPRECATED);
+
+@trigger_error('The ' . __NAMESPACE__ . '\ImageFieldTestBase is deprecated in Drupal 8.4.x and will be removed before Drupal 9.0.0. Use \Drupal\Tests\image\Functional\ImageFieldTestBase instead. See https://www.drupal.org/node/2863626.', E_USER_DEPRECATED);
 
 use Drupal\Tests\image\Kernel\ImageFieldCreationTrait;
 use Drupal\simpletest\WebTestBase;
diff --git a/core/modules/image/tests/src/Functional/ImageFieldDefaultImagesTest.php b/core/modules/image/tests/src/Functional/ImageFieldDefaultImagesTest.php
index 3d59e2867e..4866b6ce5c 100644
--- a/core/modules/image/tests/src/Functional/ImageFieldDefaultImagesTest.php
+++ b/core/modules/image/tests/src/Functional/ImageFieldDefaultImagesTest.php
@@ -6,6 +6,7 @@
 use Drupal\field\Entity\FieldConfig;
 use Drupal\file\Entity\File;
 use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\Tests\EntityTestTrait;
 use Drupal\Tests\TestFileCreationTrait;
 
 /**
@@ -19,6 +20,9 @@ class ImageFieldDefaultImagesTest extends ImageFieldTestBase {
     getTestFiles as drupalGetTestFiles;
     compareFiles as drupalCompareFiles;
   }
+  use EntityTestTrait {
+    buildEntityView as drupalBuildEntityView;
+  }
 
   /**
    * Modules to enable.
@@ -156,7 +160,6 @@ public function testDefaultImages() {
 
     // Confirm that the image default is shown for a new article node.
     $article = $this->drupalCreateNode(['type' => 'article']);
-    // TODO: drupalBuildEntityView is not available.
     $article_built = $this->drupalBuildEntityView($article);
     $this->assertEqual(
       $article_built[$field_name][0]['#item']->target_id,
diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index 2491bc84b3..39955ed48f 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -19,6 +19,7 @@
 use Drupal\Core\Test\FunctionalTestSetupTrait;
 use Drupal\Core\Url;
 use Drupal\system\Tests\Cache\AssertPageCacheContextsAndTagsTrait;
+use Drupal\Tests\EntityTestTrait;
 use Drupal\Tests\Traits\Core\CronRunTrait;
 use Drupal\Tests\TestFileCreationTrait;
 use Drupal\Tests\XdebugRequestTrait;
@@ -45,6 +46,9 @@
     createContentType as drupalCreateContentType;
   }
   use CronRunTrait;
+  use EntityTestTrait {
+    buildEntityView as drupalBuildEntityView;
+  }
   use AssertMailTrait {
     getMails as drupalGetMails;
   }
@@ -210,64 +214,6 @@ public function __construct($test_id = NULL) {
   }
 
   /**
-   * Builds the renderable view of an entity.
-   *
-   * Entities postpone the composition of their renderable arrays to #pre_render
-   * functions in order to maximize cache efficacy. This means that the full
-   * renderable array for an entity is constructed in drupal_render(). Some
-   * tests require the complete renderable array for an entity outside of the
-   * drupal_render process in order to verify the presence of specific values.
-   * This method isolates the steps in the render process that produce an
-   * entity's renderable array.
-   *
-   * @param \Drupal\Core\Entity\EntityInterface $entity
-   *   The entity to prepare a renderable array for.
-   * @param string $view_mode
-   *   (optional) The view mode that should be used to build the entity.
-   * @param null $langcode
-   *   (optional) For which language the entity should be prepared, defaults to
-   *   the current content language.
-   * @param bool $reset
-   *   (optional) Whether to clear the cache for this entity.
-   * @return array
-   *
-   * @see drupal_render()
-   */
-  protected function drupalBuildEntityView(EntityInterface $entity, $view_mode = 'full', $langcode = NULL, $reset = FALSE) {
-    $ensure_fully_built = function(&$elements) use (&$ensure_fully_built) {
-      // If the default values for this element have not been loaded yet, populate
-      // them.
-      if (isset($elements['#type']) && empty($elements['#defaults_loaded'])) {
-        $elements += \Drupal::service('element_info')->getInfo($elements['#type']);
-      }
-
-      // Make any final changes to the element before it is rendered. This means
-      // that the $element or the children can be altered or corrected before the
-      // element is rendered into the final text.
-      if (isset($elements['#pre_render'])) {
-        foreach ($elements['#pre_render'] as $callable) {
-          $elements = call_user_func($callable, $elements);
-        }
-      }
-
-      // And recurse.
-      $children = Element::children($elements, TRUE);
-      foreach ($children as $key) {
-        $ensure_fully_built($elements[$key]);
-      }
-    };
-
-    $render_controller = $this->container->get('entity.manager')->getViewBuilder($entity->getEntityTypeId());
-    if ($reset) {
-      $render_controller->resetCache([$entity->id()]);
-    }
-    $build = $render_controller->view($entity, $view_mode, $langcode);
-    $ensure_fully_built($build);
-
-    return $build;
-  }
-
-  /**
    * Checks to see whether a block appears on the page.
    *
    * @param \Drupal\block\Entity\Block $block
diff --git a/core/tests/Drupal/Tests/EntityTestTrait.php b/core/tests/Drupal/Tests/EntityTestTrait.php
new file mode 100644
index 0000000000..d9fee3efde
--- /dev/null
+++ b/core/tests/Drupal/Tests/EntityTestTrait.php
@@ -0,0 +1,75 @@
+<?php
+
+namespace Drupal\Tests;
+
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Render\Element;
+
+/**
+ * Provides methods for entities.
+ *
+ * This trait is meant to be used only by test classes.
+ */
+trait EntityTestTrait {
+
+  /**
+   * Builds the render array view of an entity.
+   *
+   * Entities postpone the composition of their render arrays to #pre_render
+   * functions in order to maximize cache efficacy. This means that the full
+   * render array for an entity is constructed in drupal_render(). Some tests
+   * require the complete render array for an entity outside of the
+   * \Renderer::render() process in order to verify the presence of specific
+   * values. This method isolates the steps in the render process that produce
+   * an entity's render array.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   The entity to prepare a render array for.
+   * @param string $view_mode
+   *   (optional) The view mode that should be used to build the entity.
+   * @param null $langcode
+   *   (optional) For which language the entity should be prepared, defaults to
+   *   the current content language.
+   * @param bool $reset
+   *   (optional) Whether to clear the cache for this entity.
+   *
+   * @return array
+   *   The render array.
+   *
+   * @see \Drupal\Core\Render\Renderer
+   */
+  protected function buildEntityView(EntityInterface $entity, $view_mode = 'full', $langcode = NULL, $reset = FALSE) {
+    $ensure_fully_built = function(&$elements) use (&$ensure_fully_built) {
+      // If the default values for this element have not been loaded yet, populate
+      // them.
+      if (isset($elements['#type']) && empty($elements['#defaults_loaded'])) {
+        $elements += $this->container->get('element_info')->getInfo($elements['#type']);
+      }
+
+      // Make any final changes to the element before it is rendered. This means
+      // that the $element or the children can be altered or corrected before the
+      // element is rendered into the final text.
+      if (isset($elements['#pre_render'])) {
+        foreach ($elements['#pre_render'] as $callable) {
+          $elements = call_user_func($callable, $elements);
+        }
+      }
+
+      // And recurse.
+      $children = Element::children($elements, TRUE);
+      foreach ($children as $key) {
+        $ensure_fully_built($elements[$key]);
+      }
+    };
+
+    $render_controller = $this->container->get('entity_type.manager')->getViewBuilder($entity->getEntityTypeId());
+    if ($reset) {
+      $render_controller->resetCache([$entity->id()]);
+    }
+    $build = $render_controller->view($entity, $view_mode, $langcode);
+    $ensure_fully_built($build);
+
+    return $build;
+  }
+
+}