diff --git a/core/lib/Drupal/Core/Test/TestDiscovery.php b/core/lib/Drupal/Core/Test/TestDiscovery.php
index 9e394a4..ecc063e 100644
--- a/core/lib/Drupal/Core/Test/TestDiscovery.php
+++ b/core/lib/Drupal/Core/Test/TestDiscovery.php
@@ -101,15 +101,7 @@ public function registerTestNamespaces() {
       }
 
       // Add PHPUnit test namespaces.
-      $this->testNamespaces["Drupal\\Tests\\$name\\Unit\\"][] = "$base_path/tests/src/Unit";
-      $this->testNamespaces["Drupal\\Tests\\$name\\Kernel\\"][] = "$base_path/tests/src/Kernel";
-      $this->testNamespaces["Drupal\\Tests\\$name\\Functional\\"][] = "$base_path/tests/src/Functional";
-      $this->testNamespaces["Drupal\\Tests\\$name\\Build\\"][] = "$base_path/tests/src/Build";
-      $this->testNamespaces["Drupal\\Tests\\$name\\FunctionalJavascript\\"][] = "$base_path/tests/src/FunctionalJavascript";
-
-      // Add discovery for traits which are shared between different test
-      // suites.
-      $this->testNamespaces["Drupal\\Tests\\$name\\Traits\\"][] = "$base_path/tests/src/Traits";
+      $this->testNamespaces["Drupal\\Tests\\$name\\"][] = "$base_path/tests/src";
     }
 
     foreach ($this->testNamespaces as $prefix => $paths) {
diff --git a/core/tests/bootstrap.php b/core/tests/bootstrap.php
index 34778e3..86e590f 100644
--- a/core/tests/bootstrap.php
+++ b/core/tests/bootstrap.php
@@ -79,7 +79,6 @@ function drupal_phpunit_contrib_extension_directory_roots($root = NULL) {
  *   An associative array of extension directories, keyed by their namespace.
  */
 function drupal_phpunit_get_extension_namespaces($dirs) {
-  $suite_names = ['Unit', 'Kernel', 'Functional', 'Build', 'FunctionalJavascript'];
   $namespaces = [];
   foreach ($dirs as $extension => $dir) {
     if (is_dir($dir . '/src')) {
@@ -88,19 +87,8 @@ function drupal_phpunit_get_extension_namespaces($dirs) {
     }
     $test_dir = $dir . '/tests/src';
     if (is_dir($test_dir)) {
-      foreach ($suite_names as $suite_name) {
-        $suite_dir = $test_dir . '/' . $suite_name;
-        if (is_dir($suite_dir)) {
-          // Register the PSR-4 directory for PHPUnit-based suites.
-          $namespaces['Drupal\\Tests\\' . $extension . '\\' . $suite_name . '\\'][] = $suite_dir;
-        }
-      }
-      // Extensions can have a \Drupal\Tests\extension\Traits namespace for
-      // cross-suite trait code.
-      $trait_dir = $test_dir . '/Traits';
-      if (is_dir($trait_dir)) {
-        $namespaces['Drupal\\Tests\\' . $extension . '\\Traits\\'][] = $trait_dir;
-      }
+      // Register the PSR-4 directory for PHPUnit-based suites.
+      $namespaces['Drupal\\Tests\\' . $extension . '\\'][] = $test_dir;
     }
   }
   return $namespaces;