diff -u b/core/modules/system/tests/src/Functional/Database/DatabaseWebTestBase.php b/core/modules/system/src/Tests/Database/DatabaseWebTestBase.php
--- b/core/modules/system/tests/src/Functional/Database/DatabaseWebTestBase.php
+++ b/core/modules/system/src/Tests/Database/DatabaseWebTestBase.php
@@ -1,23 +1,27 @@
 <?php
 
-namespace Drupal\Tests\system\Functional\Database;
+namespace Drupal\system\Tests\Database;
+
+@trigger_error(__NAMESPACE__ . '\DatabaseWebTestBase is deprecated in Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead, use \Drupal\Tests\system\Functional\Database\DatabaseTestBase', E_USER_DEPRECATED);
 
 use Drupal\KernelTests\Core\Database\DatabaseTestBase;
-use Drupal\Tests\BrowserTestBase;
+use Drupal\simpletest\WebTestBase;
 
 /**
  * Base class for databases database tests.
+ *
+ * @deprecated in Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead
+ *   use \Drupal\Tests\system\Functional\Database\DatabaseTestBase.
  */
-abstract class DatabaseWebTestBase extends BrowserTestBase {
+abstract class DatabaseWebTestBase extends WebTestBase {
 
   /**
-   * {@inheritdoc}
+   * Modules to enable.
+   *
+   * @var array
    */
   public static $modules = ['database_test'];
 
-  /**
-   * {@inheritdoc}
-   */
   protected function setUp() {
     parent::setUp();
 
diff -u b/core/modules/system/tests/src/Functional/Database/FakeRecord.php b/core/modules/system/src/Tests/Database/FakeRecord.php
--- b/core/modules/system/tests/src/Functional/Database/FakeRecord.php
+++ b/core/modules/system/src/Tests/Database/FakeRecord.php
@@ -1,6 +1,8 @@
 <?php
 
-namespace Drupal\Tests\system\Functional\Database;
+namespace Drupal\system\Tests\Database;
+
+@trigger_error(__NAMESPACE__ . '\FakeRecord is deprecated in Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead, use \Drupal\Tests\system\Functional\Database\FakeRecord', E_USER_DEPRECATED);
 
 /**
  * Fetches into a class.
@@ -9,4 +11,7 @@
  * rather than just a stdClass or array. This class is for testing that
  * functionality. (See testQueryFetchClass() below)
+ *
+ * @deprecated in Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead
+ *   use \Drupal\Tests\system\Functional\Database\FakeRecord.
  */
 class FakeRecord { }
diff -u b/core/modules/system/tests/src/Functional/Database/SelectPagerDefaultTest.php b/core/modules/system/tests/src/Functional/Database/SelectPagerDefaultTest.php
--- b/core/modules/system/tests/src/Functional/Database/SelectPagerDefaultTest.php
+++ b/core/modules/system/tests/src/Functional/Database/SelectPagerDefaultTest.php
@@ -9,7 +9,7 @@
  *
  * @group Database
  */
-class SelectPagerDefaultTest extends DatabaseWebTestBase {
+class SelectPagerDefaultTest extends DatabaseTestBase {
 
   /**
    * Confirms that a pager query returns the correct results.
@@ -98,7 +98,7 @@
     $ages = $outer_query
       ->execute()
       ->fetchCol();
-    $this->assertEquals([25, 26, 27, 28], $ages, 'Inner pager query returned the correct ages.');
+    $this->assertEqual($ages, [25, 26, 27, 28], 'Inner pager query returned the correct ages.');
   }
 
   /**
@@ -119,13 +119,14 @@
     $ages = $query
       ->execute()
       ->fetchCol();
-    $this->assertEquals(['George', 'Ringo'], $ages, 'Pager query with having expression returned the correct ages.');
+    $this->assertEqual($ages, ['George', 'Ringo'], 'Pager query with having expression returned the correct ages.');
   }
 
   /**
    * Confirms that every pager gets a valid, non-overlapping element ID.
    */
   public function testElementNumbers() {
+
     $request = Request::createFromGlobals();
     $request->query->replace([
       'page' => '3, 2, 1, 0',
@@ -140,7 +141,7 @@
       ->limit(1)
       ->execute()
       ->fetchField();
-    $this->assertEquals('Paul', $name, 'Pager query #1 with a specified element ID returned the correct results.');
+    $this->assertEqual($name, 'Paul', 'Pager query #1 with a specified element ID returned the correct results.');
 
     // Setting an element smaller than the previous one
     // should not overwrite the pager $maxElement with a smaller value.
@@ -152,7 +153,7 @@
       ->limit(1)
       ->execute()
       ->fetchField();
-    $this->assertEquals('George', $name, 'Pager query #2 with a specified element ID returned the correct results.');
+    $this->assertEqual($name, 'George', 'Pager query #2 with a specified element ID returned the correct results.');
 
     $name = db_select('test', 't')
       ->extend('Drupal\Core\Database\Query\PagerSelectExtender')
@@ -161,7 +162,8 @@
       ->limit(1)
       ->execute()
       ->fetchField();
-    $this->assertEquals('John', $name, 'Pager query #3 with a generated element ID returned the correct results.');
+    $this->assertEqual($name, 'John', 'Pager query #3 with a generated element ID returned the correct results.');
+
   }
 
 }
diff -u b/core/modules/system/tests/src/Functional/Database/SelectTableSortDefaultTest.php b/core/modules/system/tests/src/Functional/Database/SelectTableSortDefaultTest.php
--- b/core/modules/system/tests/src/Functional/Database/SelectTableSortDefaultTest.php
+++ b/core/modules/system/tests/src/Functional/Database/SelectTableSortDefaultTest.php
@@ -7,7 +7,7 @@
  *
  * @group Database
  */
-class SelectTableSortDefaultTest extends DatabaseWebTestBase {
+class SelectTableSortDefaultTest extends DatabaseTestBase {
 
   /**
    * Confirms that a tablesort query returns the correct results.
diff -u b/core/modules/system/tests/src/Functional/Database/TemporaryQueryTest.php b/core/modules/system/tests/src/Functional/Database/TemporaryQueryTest.php
--- b/core/modules/system/tests/src/Functional/Database/TemporaryQueryTest.php
+++ b/core/modules/system/tests/src/Functional/Database/TemporaryQueryTest.php
@@ -7,7 +7,7 @@
  *
  * @group Database
  */
-class TemporaryQueryTest extends DatabaseWebTestBase {
+class TemporaryQueryTest extends DatabaseTestBase {
 
   /**
    * {@inheritdoc}
diff -u b/core/tests/Drupal/KernelTests/Core/Database/FetchTest.php b/core/tests/Drupal/KernelTests/Core/Database/FetchTest.php
--- b/core/tests/Drupal/KernelTests/Core/Database/FetchTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/FetchTest.php
@@ -72,8 +72,9 @@
     $result = db_query('SELECT name FROM {test} WHERE age = :age', [':age' => 25], ['fetch' => FakeRecord::class]);
     foreach ($result as $record) {
       $records[] = $record;
-      $this->assertInstanceOf(FakeRecord::class, $record, 'Record is an object of class FakeRecord.');
-      $this->assertIdentical($record->name, 'John', '25 year old is John.');
+      if ($this->assertTrue($record instanceof FakeRecord, 'Record is an object of class FakeRecord.')) {
+        $this->assertIdentical($record->name, 'John', '25 year old is John.');
+      }
     }
 
     $this->assertIdentical(count($records), 1, 'There is only one record.');
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/system/tests/src/Functional/Database/DatabaseTestBase.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Drupal\Tests\system\Functional\Database;
+
+use Drupal\KernelTests\Core\Database\DatabaseTestBase as DatabaseKernelTestBase;
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Base class for databases database tests.
+ */
+abstract class DatabaseTestBase extends BrowserTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['database_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    DatabaseKernelTestBase::addSampleData();
+  }
+
+}