Add comprehensive test coverage and update notes

tests/Unit/PostThankControllerUnitTest.php

@@ -0,0 +1,36 @@
+<?php
+
+use App\Http\Controllers\PostThankController;
+use App\Models\Post;
+use App\Models\User;
+use Illuminate\Http\Request;
+
+it('returns unauthenticated when no user in store/destroy', function (): void {
+    $controller = new PostThankController();
+    $post = new Post([
+        'id' => 1,
+    ]);
+    $post->setRawAttributes(['id' => 1, 'thread_id' => 1, 'user_id' => null, 'body' => 'Post'], true);
+
+    $request = Request::create('/api/posts/'.$post->id.'/thanks', 'POST');
+    $request->setUserResolver(fn () => null);
+    $response = $controller->store($request, $post);
+    expect($response->getStatusCode())->toBe(401);
+
+    $request = Request::create('/api/posts/'.$post->id.'/thanks', 'DELETE');
+    $request->setUserResolver(fn () => null);
+    $response = $controller->destroy($request, $post);
+    expect($response->getStatusCode())->toBe(401);
+});
+
+it('resolveGroupColor returns null for missing roles', function (): void {
+    $controller = new PostThankController();
+    $user = User::factory()->create();
+    $user->setRelation('roles', null);
+
+    $ref = new ReflectionMethod($controller, 'resolveGroupColor');
+    $ref->setAccessible(true);
+
+    expect($ref->invoke($controller, $user))->toBeNull();
+    expect($ref->invoke($controller, null))->toBeNull();
+});