class TestSuiteBase

abstract class TestSuiteBase extends TestSuite {
    
    /**
     * Finds extensions in a Drupal installation.
     *
     * An extension is defined as a directory with an *.info.yml file in it.
     *
     * @param string $root
     *   Path to the root of the Drupal installation.
     *
     * @return string[]
     *   Associative array of extension paths, with extension name as keys.
     */
    protected function findExtensionDirectories($root) {
        $extension_roots = \drupal_phpunit_contrib_extension_directory_roots($root);
        $extension_directories = array_map('drupal_phpunit_find_extension_directories', $extension_roots);
        return array_reduce($extension_directories, 'array_merge', []);
    }
    
    /**
     * Find and add tests to the suite for core and any extensions.
     *
     * @param string $root
     *   Path to the root of the Drupal installation.
     * @param string $suite_namespace
     *   SubNamespace used to separate test suite. Examples: Unit, Functional.
     */
    protected function addTestsBySuiteNamespace($root, $suite_namespace) {
        // Core's tests are in the namespace Drupal\${suite_namespace}Tests\ and are
        // always inside of core/tests/Drupal/${suite_namespace}Tests. The exception
        // to this is Unit tests for historical reasons.
        if ($suite_namespace == 'Unit') {
            $tests = TestDiscovery::scanDirectory("Drupal\\Tests\\", "{$root}/core/tests/Drupal/Tests");
            $tests = array_flip(array_filter(array_flip($tests), function ($test_class) {
                // The Listeners directory does not contain tests. Use the class name
                // to be compatible with all operating systems.
                return !preg_match('/^Drupal\\\\Tests\\\\Listeners\\\\/', $test_class);
            }));
            $this->addTestFiles($tests);
        }
        else {
            $this->addTestFiles(TestDiscovery::scanDirectory("Drupal\\{$suite_namespace}Tests\\", "{$root}/core/tests/Drupal/{$suite_namespace}Tests"));
        }
        // Extensions' tests will always be in the namespace
        // Drupal\Tests\$extension_name\$suite_namespace\ and be in the
        // $extension_path/tests/src/$suite_namespace directory. Not all extensions
        // will have all kinds of tests.
        foreach ($this->findExtensionDirectories($root) as $extension_name => $dir) {
            $test_path = "{$dir}/tests/src/{$suite_namespace}";
            if (is_dir($test_path)) {
                $this->addTestFiles(TestDiscovery::scanDirectory("Drupal\\Tests\\{$extension_name}\\{$suite_namespace}\\", $test_path));
            }
        }
    }

}