diff --git a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
index 459950d..5b8d010 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
@@ -150,19 +150,23 @@ public function testRegister() {
 
   /**
    * @covers ::getCompiledContainerBuilder
+   *
+   * The point of this test is to have integration level testing.
    */
   public function testCompiledContainer() {
     $this->enableModules(['system', 'user']);
-    $this->installConfig('user');
+    $this->assertNull($this->installConfig('user'));
   }
 
   /**
    * @covers ::getCompiledContainerBuilder
    * @depends testCompiledContainer
+   *
+   * The point of this test is to have integration level testing.
    */
   public function testCompiledContainerIsDestructed() {
     $this->enableModules(['system', 'user']);
-    $this->installConfig('user');
+    $this->assertNull($this->installConfig('user'));
   }
 
   /**
@@ -209,7 +213,7 @@ public function testRenderWithTheme() {
     $output = \Drupal::service('renderer')->renderRoot($build);
     $this->assertEquals('core', \Drupal::theme()->getActiveTheme()->getName());
 
-    $this->assertRegExp($expected, $build['#children']);
+    $this->assertRegExp($expected, (string) $build['#children']);
     $this->assertRegExp($expected, (string) $output);
   }