class TestDiscovery

class TestDiscovery {
  
  /**
   * Cached map of all test namespaces to respective directories.
   *
   * @var array<string,string>
   */
  protected array $testNamespaces;
  public function __construct(protected readonly string $root, protected readonly ClassLoader $classLoader) {
  }
  
  /**
   * Registers test namespaces of all extensions and core test classes.
   *
   * @return array<string,string>
   *   An associative array whose keys are PSR-4 namespace prefixes and whose
   *   values are directory names.
   */
  public function registerTestNamespaces() : array {
    if (isset($this->testNamespaces)) {
      return $this->testNamespaces;
    }
    $this->testNamespaces = [];
    $existing = $this->classLoader
      ->getPrefixesPsr4();
    // 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\\TestTools\\'] = [
      $this->root . '/core/tests/Drupal/TestTools',
    ];
    foreach ($this->getExtensions() as $name => $extension) {
      $base_path = $this->root . '/' . $extension->getPath();
      // Add namespace of disabled/uninstalled extensions.
      if (!isset($existing["Drupal\\{$name}\\"])) {
        $this->classLoader
          ->addPsr4("Drupal\\{$name}\\", "{$base_path}/src");
      }
      // Add PHPUnit test namespaces.
      $this->testNamespaces["Drupal\\Tests\\{$name}\\"][] = "{$base_path}/tests/src";
    }
    // Expose tests provided by core recipes.
    $base_path = $this->root . '/core/recipes';
    if ($handle = @opendir($base_path)) {
      while (($recipe = readdir($handle)) !== FALSE) {
        $this->testNamespaces["Drupal\\FunctionalTests\\Recipe\\Core\\{$recipe}\\"][] = "{$base_path}/{$recipe}/tests/src/Functional";
      }
      closedir($handle);
    }
    foreach ($this->testNamespaces as $prefix => $paths) {
      $this->classLoader
        ->addPsr4($prefix, $paths);
    }
    return $this->testNamespaces;
  }
  
  /**
   * Returns all available extensions.
   *
   * @return array<string,\Drupal\Core\Extension\Extension>
   *   An array of Extension objects, keyed by extension name.
   */
  protected function getExtensions() : array {
    $listing = new ExtensionDiscovery($this->root);
    // Ensure that tests in all profiles are discovered.
    $listing->setProfileDirectories([]);
    $extensions = $listing->scan('module', TRUE);
    $extensions += $listing->scan('profile', TRUE);
    $extensions += $listing->scan('theme', TRUE);
    return $extensions;
  }

}