diff --git a/core/modules/system/src/Tests/Installer/ConfigAfterInstallerTestBase.php b/core/modules/system/src/Tests/Installer/ConfigAfterInstallerTestBase.php
index 4611e90..aa3ec3e 100644
--- a/core/modules/system/src/Tests/Installer/ConfigAfterInstallerTestBase.php
+++ b/core/modules/system/src/Tests/Installer/ConfigAfterInstallerTestBase.php
@@ -20,6 +20,12 @@
 
   use AssertConfigTrait;
 
+  /**
+   * Ensures that all the installed config looks like the exported one.
+   *
+   * @param array $skipped_config
+   *   An array of skipped config.
+   */
   protected function assertInstalledConfig(array $skipped_config) {
     /** @var \Drupal\Core\Config\StorageInterface $active_config_storage */
     $active_config_storage = $this->container->get('config.storage');
diff --git a/core/modules/system/src/Tests/Installer/MinimalInstallerTest.php b/core/modules/system/src/Tests/Installer/MinimalInstallerTest.php
index 5946212..54c07b3 100644
--- a/core/modules/system/src/Tests/Installer/MinimalInstallerTest.php
+++ b/core/modules/system/src/Tests/Installer/MinimalInstallerTest.php
@@ -7,18 +7,14 @@
 
 namespace Drupal\system\Tests\Installer;
 
-use Drupal\Core\Config\FileStorage;
-use Drupal\Core\Config\InstallStorage;
-use Drupal\Core\Config\StorageInterface;
 use Drupal\KernelTests\AssertConfigTrait;
-use Drupal\simpletest\InstallerTestBase;
 
 /**
  * Tests the interactive installer installing the minimal profile.
  *
  * @group Installer
  */
-class MinimalInstallerTest extends InstallerTestBase {
+class MinimalInstallerTest extends ConfigAfterInstallerTestBase {
 
   use AssertConfigTrait;
 
@@ -31,25 +27,7 @@ class MinimalInstallerTest extends InstallerTestBase {
    * Ensures that the exported minimal configuration is up to date.
    */
   public function testMinimalConfig() {
-    /** @var \Drupal\Core\Config\StorageInterface $active_config_storage */
-    $active_config_storage = $this->container->get('config.storage');
-    /** @var \Drupal\Core\Config\ConfigManagerInterface $config_manager */
-    $config_manager = $this->container->get('config.manager');
-
-    $profile = 'minimal';
-
-    $default_install_path = 'core/profiles/' . $profile . '/' . InstallStorage::CONFIG_INSTALL_DIRECTORY;
-    $profile_config_storage = new FileStorage($default_install_path, StorageInterface::DEFAULT_COLLECTION);
-
-    $skipped_config = [];
-    foreach ($profile_config_storage->listAll() as $config_name) {
-      $result = $config_manager->diff($profile_config_storage, $active_config_storage, $config_name);
-      try {
-        $this->assertConfigDiff($result, $config_name, $skipped_config);
-      }
-      catch (\Exception $e) {
-        $this->fail($e->getMessage());
-      }
-    }
+    $this->assertInstalledConfig([]);
   }
+
 }
diff --git a/core/modules/system/src/Tests/Installer/StandardInstallerTest.php b/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
index 72a5072..184e07b 100644
--- a/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
+++ b/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
@@ -7,20 +7,12 @@
 
 namespace Drupal\system\Tests\Installer;
 
-use Drupal\Core\Config\FileStorage;
-use Drupal\Core\Config\InstallStorage;
-use Drupal\Core\Config\StorageInterface;
-use Drupal\KernelTests\AssertConfigTrait;
-use Drupal\simpletest\InstallerTestBase;
-
 /**
  * Tests the interactive installer installing the standard profile.
  *
  * @group Installer
  */
-class StandardInstallerTest extends InstallerTestBase {
-
-  use AssertConfigTrait;
+class StandardInstallerTest extends ConfigAfterInstallerTestBase {
 
   /**
    * {@inheritdoc}
@@ -52,16 +44,6 @@ protected function setUpSite() {
    * Ensures that the exported standard configuration is up to date.
    */
   public function testStandardConfig() {
-    /** @var \Drupal\Core\Config\StorageInterface $active_config_storage */
-    $active_config_storage = $this->container->get('config.storage');
-    /** @var \Drupal\Core\Config\ConfigManagerInterface $config_manager */
-    $config_manager = $this->container->get('config.manager');
-
-    $profile = 'standard';
-
-    $default_install_path = 'core/profiles/' . $profile . '/' . InstallStorage::CONFIG_INSTALL_DIRECTORY;
-    $profile_config_storage = new FileStorage($default_install_path, StorageInterface::DEFAULT_COLLECTION);
-
     $skipped_config = [];
     // \Drupal\simpletest\WebTestBase::installParameters() uses
     // simpletest@example.com as mail address.
@@ -75,15 +57,7 @@ public function testStandardConfig() {
     $skipped_config['filter.format.restricted_html'][] = 'roles:';
     $skipped_config['filter.format.restricted_html'][] = ' - anonymous';
 
-    foreach ($profile_config_storage->listAll() as $config_name) {
-      $result = $config_manager->diff($profile_config_storage, $active_config_storage, $config_name);
-      try {
-        $this->assertConfigDiff($result, $config_name, $skipped_config);
-      }
-      catch (\Exception $e) {
-        $this->fail($e->getMessage());
-      }
-    }
+    $this->assertInstalledConfig($skipped_config);
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/AssertConfigTrait.php b/core/tests/Drupal/KernelTests/AssertConfigTrait.php
index 1545814..437cf99 100644
--- a/core/tests/Drupal/KernelTests/AssertConfigTrait.php
+++ b/core/tests/Drupal/KernelTests/AssertConfigTrait.php
@@ -18,10 +18,16 @@
    * Ensures that a specific config diff does not contain unwanted changes.
    *
    * @param \Drupal\Component\Diff\Diff $result
-   * @param $config_name
+   *   The diff result for the passed in config name.
+   * @param string $config_name
+   *   The config name to check.
    * @param array $skipped_config
+   *   An array of skipped config, keyed by string. If the value is TRUE, the
+   *   entire file will be ignored, otherwise its an array of strings which are
+   *   ignored.
    *
    * @throws \Exception
+   *   Thrown when a configuration is different.
    */
   protected function assertConfigDiff(Diff $result, $config_name, array $skipped_config) {
     foreach ($result->getEdits() as $op) {
@@ -31,7 +37,7 @@ protected function assertConfigDiff(Diff $result, $config_name, array $skipped_c
           break;
         case 'Drupal\Component\Diff\Engine\DiffOpDelete':
         case 'Drupal\Component\Diff\Engine\DiffOpChange':
-          // Its not part of the skipped config, so we can directly throw the
+          // It is not part of the skipped config, so we can directly throw the
           // exception.
           if (!in_array($config_name, array_keys($skipped_config))) {
             throw new \Exception($config_name . ': ' . var_export($op, TRUE));
diff --git a/core/tests/Drupal/KernelTests/Config/DefaultConfigTest.php b/core/tests/Drupal/KernelTests/Config/DefaultConfigTest.php
index aa0ab63..0ee34e1 100644
--- a/core/tests/Drupal/KernelTests/Config/DefaultConfigTest.php
+++ b/core/tests/Drupal/KernelTests/Config/DefaultConfigTest.php
@@ -80,7 +80,7 @@ public function testModuleConfig($module) {
     $module_config_storage = new FileStorage($default_install_path, StorageInterface::DEFAULT_COLLECTION);
 
     // The following config entries are changed on module install, so compare
-    // it doesn't make sense.
+    // them doesn't make sense.
     $skipped_config = [];
     $skipped_config['locale.settings'][] = 'path: ';
     $skipped_config['syslog.settings'][] = 'facility: ';