Issue #3449743 by catch: Try to optimize test ordering when run-tests.sh is...

Issue #3449743 by catch: Try to optimize test ordering when run-tests.sh is used with a mixture of test types

(cherry picked from commit 17ec849e)

core/lib/Drupal/Core/Test/TestDiscovery.php

@@ -80,12 +80,15 @@ public function registerTestNamespaces() {
 
     $existing = $this->classLoader->getPrefixesPsr4();
 
-    // Add PHPUnit test namespaces of Drupal core.
-    $this->testNamespaces['Drupal\\Tests\\'] = [$this->root . '/core/tests/Drupal/Tests'];
+    // Add PHPUnit test namespaces of Drupal core. Order the namespaces by the
+    // test types that tend to be slowest first, to optimize overall test times
+    // when multiple different test types are run concurrently by the same test
+    // runner.
+    $this->testNamespaces['Drupal\\FunctionalJavascriptTests\\'] = [$this->root . '/core/tests/Drupal/FunctionalJavascriptTests'];
+    $this->testNamespaces['Drupal\\FunctionalTests\\'] = [$this->root . '/core/tests/Drupal/FunctionalTests'];
     $this->testNamespaces['Drupal\\BuildTests\\'] = [$this->root . '/core/tests/Drupal/BuildTests'];
+    $this->testNamespaces['Drupal\\Tests\\'] = [$this->root . '/core/tests/Drupal/Tests'];
     $this->testNamespaces['Drupal\\KernelTests\\'] = [$this->root . '/core/tests/Drupal/KernelTests'];
-    $this->testNamespaces['Drupal\\FunctionalTests\\'] = [$this->root . '/core/tests/Drupal/FunctionalTests'];
-    $this->testNamespaces['Drupal\\FunctionalJavascriptTests\\'] = [$this->root . '/core/tests/Drupal/FunctionalJavascriptTests'];
     $this->testNamespaces['Drupal\\TestTools\\'] = [$this->root . '/core/tests/Drupal/TestTools'];
 
     $this->availableExtensions = [];