diff --git a/composer.lock b/composer.lock
index 84fadea8c..a1cc1913c 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4046,16 +4046,16 @@
         },
         {
             "name": "drupal/helfi_api_base",
-            "version": "2.5.3",
+            "version": "2.5.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/City-of-Helsinki/drupal-module-helfi-api-base.git",
-                "reference": "f5fab16526d75c612e420a68ebe933efb5c72a0e"
+                "reference": "2a0a4fb2ea863232dc3eed32a3e8104fdffab178"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/City-of-Helsinki/drupal-module-helfi-api-base/zipball/f5fab16526d75c612e420a68ebe933efb5c72a0e",
-                "reference": "f5fab16526d75c612e420a68ebe933efb5c72a0e",
+                "url": "https://api.github.com/repos/City-of-Helsinki/drupal-module-helfi-api-base/zipball/2a0a4fb2ea863232dc3eed32a3e8104fdffab178",
+                "reference": "2a0a4fb2ea863232dc3eed32a3e8104fdffab178",
                 "shasum": ""
             },
             "require": {
@@ -4081,10 +4081,10 @@
             ],
             "description": "Helfi - API Base",
             "support": {
-                "source": "https://github.com/City-of-Helsinki/drupal-module-helfi-api-base/tree/2.5.3",
+                "source": "https://github.com/City-of-Helsinki/drupal-module-helfi-api-base/tree/2.5.4",
                 "issues": "https://github.com/City-of-Helsinki/drupal-module-helfi-api-base/issues"
             },
-            "time": "2023-09-13T05:29:57+00:00"
+            "time": "2023-09-14T09:11:02+00:00"
         },
         {
             "name": "drupal/helfi_azure_fs",
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 1a56d5be1..0ae082a9a 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -41,9 +41,13 @@
   </testsuite>
   <testsuite name="existing-site">
     <directory>./tests/dtt/src/ExistingSite</directory>
+    <directory>./public/modules/custom/*/tests/src/ExistingSite</directory>
+    <directory>./public/modules/contrib/*/tests/src/ExistingSite</directory>
   </testsuite>
   <testsuite name="existing-site-javascript">
     <directory>./tests/dtt/src/ExistingSiteJavascript</directory>
+    <directory>./public/modules/custom/*/tests/src/ExistingSiteJavascript</directory>
+    <directory>./public/modules/contrib/*/tests/src/ExistingSiteJavascript</directory>
   </testsuite>
 </testsuites>
 <listeners>
diff --git a/tests/dtt/src/ExistingSite/ExistingSiteTestBase.php b/tests/dtt/src/ExistingSite/ExistingSiteTestBase.php
deleted file mode 100644
index 235177288..000000000
--- a/tests/dtt/src/ExistingSite/ExistingSiteTestBase.php
+++ /dev/null
@@ -1,34 +0,0 @@
-<?php
-
-declare(strict_types = 1);
-
-namespace Drupal\Tests\dtt\ExistingSite;
-
-use Drupal\Tests\dtt\Traits\DefaultConfigurationTrait;
-use weitzman\DrupalTestTraits\ExistingSiteBase;
-
-/**
- * Existing site test base.
- */
-abstract class ExistingSiteTestBase extends ExistingSiteBase {
-
-  use DefaultConfigurationTrait;
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setUp() : void {
-    parent::setUp();
-
-    $this->setupDefaultConfiguration();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function tearDown() : void {
-    parent::tearDown();
-    $this->tearDownDefaultConfiguration();
-  }
-
-}
diff --git a/tests/dtt/src/ExistingSite/NewsContentTypeTest.php b/tests/dtt/src/ExistingSite/NewsContentTypeTest.php
index 17f5fe492..82bbee1b4 100644
--- a/tests/dtt/src/ExistingSite/NewsContentTypeTest.php
+++ b/tests/dtt/src/ExistingSite/NewsContentTypeTest.php
@@ -5,6 +5,7 @@
 namespace Drupal\Tests\dtt\ExistingSite;
 
 use Drupal\Core\Session\AccountInterface;
+use Drupal\Tests\helfi_api_base\Functional\ExistingSiteTestBase;
 
 /**
  * Tests news endpoint.
@@ -54,7 +55,11 @@ public function assertNodeCreation() : void {
    * Asserts that news json list has the expected item.
    */
   public function assertJsonApiList() : void {
-    $this->drupalGetWithLanguage('/jsonapi/node/news');
+    // Sort items by changed date to make sure our newly added item is visible.
+    $this->drupalGetWithLanguage('/jsonapi/node/news', options: ['query' => [
+      'sort[changed][path]' => 'changed',
+      'sort[changed][direction]' => 'DESC',
+    ]]);
     $this->assertSession()->statusCodeEquals(200);
     $json = json_decode($this->getSession()->getPage()->getContent(), TRUE);
 
diff --git a/tests/dtt/src/ExistingSiteJavascript/ExistingSiteJavascriptTestBase.php b/tests/dtt/src/ExistingSiteJavascript/ExistingSiteJavascriptTestBase.php
deleted file mode 100644
index 9bd0725b1..000000000
--- a/tests/dtt/src/ExistingSiteJavascript/ExistingSiteJavascriptTestBase.php
+++ /dev/null
@@ -1,34 +0,0 @@
-<?php
-
-declare(strict_types = 1);
-
-namespace Drupal\Tests\dtt\ExistingSiteJavascript;
-
-use Drupal\Tests\dtt\Traits\DefaultConfigurationTrait;
-use weitzman\DrupalTestTraits\ExistingSiteWebDriverTestBase;
-
-/**
- * Existing site test base.
- */
-abstract class ExistingSiteJavascriptTestBase extends ExistingSiteWebDriverTestBase {
-
-  use DefaultConfigurationTrait;
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setUp() {
-    parent::setUp();
-
-    $this->setupDefaultConfiguration();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function tearDown() {
-    parent::tearDown();
-    $this->tearDownDefaultConfiguration();
-  }
-
-}
diff --git a/tests/dtt/src/Traits/DefaultConfigurationTrait.php b/tests/dtt/src/Traits/DefaultConfigurationTrait.php
deleted file mode 100644
index a0f100a03..000000000
--- a/tests/dtt/src/Traits/DefaultConfigurationTrait.php
+++ /dev/null
@@ -1,92 +0,0 @@
-<?php
-
-declare(strict_types = 1);
-
-namespace Drupal\Tests\dtt\Traits;
-
-use Drupal\Core\Config\Config;
-use Drupal\Core\Language\LanguageInterface;
-use Drupal\Core\Url;
-
-/**
- * Basic configuration for each test.
- */
-trait DefaultConfigurationTrait {
-
-  /**
-   * The default language.
-   *
-   * @var string
-   */
-  protected string $defaultLanguage = '';
-
-  /**
-   * Gets the language object for given langcode.
-   *
-   * @param string $langcode
-   *   The langcode.
-   *
-   * @return \Drupal\Core\Language\LanguageInterface
-   *   The language.
-   */
-  protected function getLanguage(string $langcode) : LanguageInterface {
-    return \Drupal::languageManager()->getLanguage($langcode);
-  }
-
-  /**
-   * Wrapper for drupalGet() to always set language code.
-   *
-   * @param string|\Drupal\Core\Url $url
-   *   The url.
-   * @param string $langcode
-   *   The langcode.
-   * @param array $options
-   *   The options.
-   * @param array $headers
-   *   The headers.
-   */
-  protected function drupalGetWithLanguage(string|Url $url, string $langcode = 'en', array $options = [], array $headers = []) : void {
-    $options['language'] = $this->getLanguage($langcode);
-    $this->drupalGet($url, $options, $headers);
-  }
-
-  /**
-   * Set up the default configuration.
-   */
-  protected function setupDefaultConfiguration() : void {
-    $this->defaultLanguage = $this->getDefaultLanguageConfiguration()
-      ->get('selected_langcode');
-    $this->setDefaultLanguage('en');
-  }
-
-  /**
-   * Restores the default configuration.
-   */
-  protected function tearDownDefaultConfiguration() : void {
-    $this->setDefaultLanguage($this->defaultLanguage);
-  }
-
-  /**
-   * Gets the configuration.
-   *
-   * @return \Drupal\Core\Config\Config
-   *   The default configuration.
-   */
-  protected function getDefaultLanguageConfiguration() : Config {
-    return \Drupal::configFactory()
-      ->getEditable('language.negotiation');
-  }
-
-  /**
-   * Sets the default language.
-   *
-   * @param string $langcode
-   *   The langcode to set as default.
-   */
-  protected function setDefaultLanguage(string $langcode) : void {
-    $this->getDefaultLanguageConfiguration()
-      ->set('selected_langcode', $langcode)
-      ->save();
-  }
-
-}