fixed functional test when enablePrettyUrl is false.

config/codeception/functional.php

@@ -7,5 +7,11 @@ return [
 		'db' => [
 			'dsn' => 'mysql:host=localhost;dbname=yii2basic_functional',
 		],
+		'request' => [
+			'enableCsrfValidation' => false,
+		],
+		'urlManager' => [
+			'baseUrl' => '/web/index.php',
+		],
 	],
 ];

tests/functional/_bootstrap.php

@@ -1,8 +1,4 @@
 <?php
 
-$config = yii\helpers\ArrayHelper::merge(
-	require(__DIR__ . '/../../config/web.php'),
-	require(__DIR__ . '/../../config/codeception/functional.php')
-);
-
-$application = new yii\web\Application($config);
+// create an application instance to support URL creation before running any test
+Yii::createObject(require(__DIR__ . '/../../web/index-test-functional.php'));