Add more tests.

tests/Unit/ContactControllerCest.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Unit;
+
+use App\Tests\Support\UnitTester;
+use App\UseCase\Contact\ContactController;
+use Yii;
+use yii\base\InvalidConfigException;
+
+final class ContactControllerCest
+{
+    public function testIndex(UnitTester $I): void
+    {
+        $contactControler = new ContactController('contact', Yii::$app);
+
+        $contactControler->formModelClass = '';
+
+        $I->expectThrowable(
+            new InvalidConfigException('The "formModelClass" property must be set.'),
+            static fn() => $contactControler->runAction('index'),
+        );
+    }
+}