diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceRestTestCoverageTest.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceRestTestCoverageTest.php
new file mode 100644
index 0000000..0f19839
--- /dev/null
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceRestTestCoverageTest.php
@@ -0,0 +1,112 @@
+<?php
+
+namespace Drupal\Tests\rest\Functional\EntityResource;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Checks that all core content/config entity types have REST test coverage.
+ */
+class EntityResourceRestTestCoverageTest extends BrowserTestBase {
+
+  /**
+   * Entities definitions array.
+   *
+   * @var array
+   */
+  protected $definitions;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $all_modules = system_rebuild_module_data();
+    $all_modules = array_filter($all_modules, function ($module) {
+      // Filter contrib, hidden, already enabled modules and modules in the
+      // Testing package.
+      if ($module->origin !== 'core' || !empty($module->info['hidden']) || $module->status == TRUE || $module->info['package'] == 'Testing') {
+        return FALSE;
+      }
+      return TRUE;
+    });
+
+    \Drupal::service('module_installer')->install(array_keys($all_modules));
+
+    $this->definitions = \Drupal::entityTypeManager()->getDefinitions();
+  }
+
+  /**
+   * Tests that all core content/config entity types have REST test coverage.
+   */
+  public function testEntityTypeRestTestCoverage() {
+    $tests = [
+      'Drupal\Tests\rest\Functional\EntityResource' => [
+        'JsonAnonTest',
+        'JsonBasicAuthTest',
+        'JsonCookieTest',
+      ],
+      'Drupal\Tests\hal\Functional\EntityResource' => [
+        'HalJsonAnonTest',
+        'HalJsonBasicAuthTest',
+        'HalJsonCookieTest',
+      ],
+    ];
+
+    $problems = [];
+    foreach ($this->definitions as $info) {
+      $class_name_full = $info->getClass();
+      $class_name = basename($class_name_full);
+      foreach ($tests as $path => $postfixes) {
+        foreach ($postfixes as $postfix) {
+          $class = $path . '\\' . $class_name . '\\' . $class_name . $postfix;
+          if (!class_exists($class)) {
+            $problems[] = "$class_name ($class_name_full)";
+            break 2;
+          }
+        }
+      }
+    }
+    $all = count($this->definitions);
+    $bad = count($problems);
+    $this->assertSame([], $problems, $this->getLlamaMessage($bad, $all));
+  }
+
+  /**
+   * Message from Llama.
+   *
+   * @param int $b
+   *   A count of entities without test coverage.
+   * @param int $a
+   *   A count of all entities.
+   *
+   * @return string
+   *   An information about progress of REST test coverage.
+   */
+  protected function getLlamaMessage($b, $a) {
+
+    if ($b < 10) {
+      $b = "0$b";
+    }
+
+    $message = "
+      ________________________
+     /           Hi!          \\
+    | What about a few of cool |
+    |        REST tests?       |
+    |                          |
+    |     Progress: $b/$a.     |
+    | ________________________/
+    |/  
+//  o
+l'>
+ll
+llama
+|| ||
+'' ''
+";
+    return $message;
+  }
+
+}