Tests: add NullControl coverage

Author: felixure

tests/Cases/UI/NullControl.phpt

@@ -0,0 +1,17 @@
+<?php declare(strict_types = 1);
+
+use Contributte\Application\UI\NullControl;
+use Contributte\Tester\Toolkit;
+use Tester\Assert;
+
+require_once __DIR__ . '/../../bootstrap.php';
+
+Toolkit::test(function (): void {
+	$control = new NullControl();
+
+	ob_start();
+	$control->render();
+	$output = ob_get_clean();
+
+	Assert::same('', $output);
+});