diff --git a/scaffold/phpunit-testtraits.xml b/scaffold/phpunit-testtraits.xml
index 88716b56..20251302 100644
--- a/scaffold/phpunit-testtraits.xml
+++ b/scaffold/phpunit-testtraits.xml
@@ -58,28 +58,46 @@
   </extensions>
   <testsuites>
     <testsuite name="unit">
-      <directory>../../../../web/modules/custom/**/tests/src/Unit</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/Unit</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/Unit</directory>
+      <directory>../../../../web/modules/custom/*/tests/src/Unit</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/Unit</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/Unit</directory>
+      <directory>../../../../web/themes/custom/*/tests/src/Unit</directory>
+      <directory>../../../../web/themes/custom/*/*/tests/src/Unit</directory>
+      <directory>../../../../web/profiles/custom/*/tests/src/Unit</directory>
+      <directory>../../../../web/profiles/custom/*/*/tests/src/Unit</directory>
       <directory>../../../../test/phpunit/*/Unit</directory>
     </testsuite>
     <testsuite name="kernel">
-      <directory>../../../../web/modules/custom/**/tests/src/Kernel</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/Kernel</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/Kernel</directory>
+      <directory>../../../../web/modules/custom/*/tests/src/Kernel</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/Kernel</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/Kernel</directory>
       <directory>../../../../test/phpunit/*/Kernel</directory>
     </testsuite>
     <testsuite name="functional">
-      <directory>../../../../web/modules/custom/**/tests/src/Functional</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/Functional</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/Functional</directory>
+      <directory>../../../../web/modules/custom/*/tests/src/Functional</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/Functional</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/Functional</directory>
       <directory>../../../../test/phpunit/*/Functional</directory>
     </testsuite>
     <testsuite name="functional-javascript">
-      <directory>../../../../web/modules/custom/**/tests/src/FunctionalJavaScript</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/FunctionalJavaScript</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/FunctionalJavaScript</directory>
+      <directory>../../../../web/modules/custom/*/tests/src/FunctionalJavaScript</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/FunctionalJavaScript</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/FunctionalJavaScript</directory>
       <directory>../../../../test/phpunit/*/FunctionalJavaScript</directory>
     </testsuite>
+    <testsuite name="existing-site">
+      <!-- Assumes tests are namespaced as \Drupal\Tests\custom_foo\ExistingSite. -->
+      <directory>../../../../web/modules/custom/*/tests/src/ExistingSite</directory>
+      <directory>../../../../test/phpunit/*/ExistingSite</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/ExistingSite</directory>
+      <directory>../../../../test/phpunit/*/ExistingSite</directory>
+    </testsuite>
+    <testsuite name="existing-site-javascript">
+      <!-- Assumes tests are namespaced as \Drupal\Tests\custom_foo\ExistingSiteJavascript. -->
+      <directory>../../../../web/modules/custom/*/tests/src/ExistingSiteJavascript</directory>
+      <directory>../../../../test/phpunit/*/ExistingSiteJavascript</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/ExistingSiteJavaScript</directory>
+      <directory>../../../../test/phpunit/*/ExistingSiteJavaScript</directory>
+    </testsuite>
   </testsuites>
 </phpunit>
diff --git a/scaffold/phpunit.xml b/scaffold/phpunit.xml
index 590e84df..da44e35c 100644
--- a/scaffold/phpunit.xml
+++ b/scaffold/phpunit.xml
@@ -55,27 +55,28 @@
   </extensions>
   <testsuites>
     <testsuite name="unit">
-      <directory>../../../../web/modules/custom/**/tests/src/Unit</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/Unit</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/Unit</directory>
+
+      <directory>../../../../web/modules/custom/*/tests/src/Unit</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/Unit</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/Unit</directory>
       <directory>../../../../test/phpunit/*/Unit</directory>
     </testsuite>
     <testsuite name="kernel">
-      <directory>../../../../web/modules/custom/**/tests/src/Kernel</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/Kernel</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/Kernel</directory>
+      <directory>../../../../web/modules/custom/*/tests/src/Kernel</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/Kernel</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/Kernel</directory>
       <directory>../../../../test/phpunit/*/Kernel</directory>
     </testsuite>
     <testsuite name="functional">
-      <directory>../../../../web/modules/custom/**/tests/src/Functional</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/Functional</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/Functional</directory>
+      <directory>../../../../web/modules/custom/*/tests/src/Functional</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/Functional</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/Functional</directory>
       <directory>../../../../test/phpunit/*/Functional</directory>
     </testsuite>
     <testsuite name="functional-javascript">
-      <directory>../../../../web/modules/custom/**/tests/src/FunctionalJavaScript</directory>
-      <directory>../../../../web/themes/custom/**/tests/src/FunctionalJavaScript</directory>
-      <directory>../../../../web/profiles/custom/**/tests/src/FunctionalJavaScript</directory>
+      <directory>../../../../web/modules/custom/*/tests/src/FunctionalJavaScript</directory>
+      <directory>../../../../web/modules/custom/*/*/tests/src/FunctionalJavaScript</directory>
+      <directory>../../../../web/modules/custom/*/modules/*/tests/src/FunctionalJavaScript</directory>
       <directory>../../../../test/phpunit/*/FunctionalJavaScript</directory>
     </testsuite>
   </testsuites>