test element controller mapping

backend/tests/Unit/Controllers/ElementControllerTest.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace Tests\Unit\Controllers;
+
+use App\Controllers\ElementController;
+use App\Element\CreateElementDto;
+use App\Element\Element;
+use App\Element\UseCases\GetElement\GetElement;
+use App\Set\Set as DomainSet;
+use Tests\Fakes\FakeElementRepository;
+use Tests\TestCase;
+
+class ElementControllerTest extends TestCase
+{
+    private ElementController $controller;
+
+    private FakeElementRepository $elementRepo;
+
+    protected function setUp(): void
+    {
+        $this->elementRepo = new FakeElementRepository();
+        $getElement = new GetElement($this->elementRepo);
+        $this->controller = new ElementController($getElement);
+    }
+
+    public function testShowReturnsElementPayload(): void
+    {
+        $element = $this->createElement('Baderech HaAvodah');
+
+        $response = $this->controller->show($element->getId());
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $body = json_decode($response->getContent(), true);
+        $this->assertSame($element->getId(), $body['element']['id']);
+        $this->assertSame('Baderech HaAvodah', $body['element']['title']);
+    }
+
+    public function testShowReturns400WhenIdMissing(): void
+    {
+        $response = $this->controller->show(null);
+
+        $this->assertEquals(400, $response->getStatusCode());
+        $this->assertSame(
+            ['error' => 'id is required'],
+            json_decode($response->getContent(), true),
+        );
+    }
+
+    public function testShowReturns404WhenElementDoesNotExist(): void
+    {
+        $response = $this->controller->show(999);
+
+        $this->assertEquals(404, $response->getStatusCode());
+        $this->assertSame(
+            ['error' => 'Element not found'],
+            json_decode($response->getContent(), true),
+        );
+    }
+
+    private function createElement(string $title): Element
+    {
+        $set = new DomainSet(
+            id: 1,
+            name: 'Baderech',
+            description: 'Baderech description',
+            iconImageUrl: '/assets/baderech-icon.png',
+        );
+
+        return $this->elementRepo->create(new CreateElementDto(
+            set: $set,
+            title: $title,
+            parentElement: null,
+        ));
+    }
+}