Laravel Dusk feature tests - getting 403 errors - laravel

Question

I have a test file in the tests/Feature directory with the following contents:
<?php
namespace Tests\Feature;
use Tests\TestCase;
use Illuminate\Foundation\Testing\WithFaker;
use Illuminate\Foundation\Testing\RefreshDatabase;
class UserTest extends TestCase
{
public function testA()
{
$response = $this->actingAs(\App\AdminUser::find(1))
->json('GET', '/users');
$response->assertStatus(200);
}
public function testB()
{
$response = $this->actingAs(\App\AdminUser::find(1))
->json('GET', '/users');
$response->assertStatus(200);
}
}
The problem is that when both tests are executed the assertion in the second one fails with the following error: Expected status code 200 but received 403. - Laravel throws an AccessDeniedHttpException for some reason.
If I comment out either test method the other one works.
Any ideas would be much appreciated.
--- Edit ---
Here's what's in the controller method:
public function index() {
return view('users.index');
}
And the definition in the routes file:
Route::group(['prefix' => 'users', 'as' => 'users.'], function () {
Route::get('/', ['as' => 'index', 'uses' => 'UserController#index']);
Route::get('datatables', ['as' => 'datatables', 'uses' => 'UserController#datatables']);
Route::get('show/{id}', ['as' => 'show', 'uses' => 'UserController#index']);
});
--- Edit 2 ---
Turns out this is an issue with the package I'm using. Further info: https://github.com/JosephSilber/bouncer/issues/306