tests: add singel administration unit case

tests/administrative-unit.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types = 1);
+
+use HnutiBrontosaurus\BisClient\BisClient;
+use HnutiBrontosaurus\BisClient\NotFound;
+
+
+/** @var BisClient $client */
+$client = require_once __DIR__ . '/bootstrap.php';
+?>
+
+<h2>Administration unit</h2>
+<form method="get">
+	ID: <input type="text" name="id" value="<?php echo $_GET['id'] ?>">
+	<input type="submit" value="Go">
+</form>
+
+<?php
+
+if (empty($_GET['id'])) {
+	exit;
+}
+
+$id = (int) $_GET['id'];
+$units = $client->getAdministrationUnits();
+foreach ($units as $unit) {
+	if ($unit->getId() === $id) {
+		dump($unit);
+		exit;
+	}
+}
+
+echo 'not found';

tests/index.php

@@ -2,6 +2,7 @@
 	<li><a href="events.php">events</a></li>
 	<li><a href="event.php">event</a></li>
 	<li><a href="administrative-units.php">administrative units</a></li>
+	<li><a href="administrative-unit.php">administrative unit</a></li>
 	<li><a href="opportunities.php">opportunities</a></li>
 	<li><a href="opportunity.php">opportunity</a></li>
 </ul>