yii2-swiftmailer/apps/basic/tests/functional/_config.php

<?php

// set correct script paths
$_SERVER['SCRIPT_FILENAME'] = TEST_ENTRY_FILE;
$_SERVER['SCRIPT_NAME'] = TEST_ENTRY_URL;

return yii\helpers\ArrayHelper::merge(
	require(__DIR__ . '/../../config/web.php'),
	require(__DIR__ . '/../_config.php'),
	[
		'components' => [
			'db' => [
				'dsn' => 'mysql:host=localhost;dbname=yii2_basic_functional',
			],
			'mail' => [
				'useFileTransport' => true,
			],
			'urlManager' => [
				'showScriptName' => true,
			],
		],
	]
);