Laravel testing: DatabaseTransactions, rollback is not working

I would like to test a route that is adding values to the DB.

Here is my test:

use DatabaseTransactions;
public function testValues()
{
    $this->withoutMiddleware(); // Disabling the auth middleware


    $response = $this->json('POST', '/values', [

        'values' => 'THIS_IS_A_TEST',

    ]);
     $response
        ->assertStatus(200);



    $this->assertDatabaseHas('values', [
        'value' => 'THIS_IS_A_TEST'
    ]);
}

The last assertion is always wrong because the database is empty. I think it's because the last assertion is done before the values are added to the DB.

Can I execute the second assertion only when the first one has been executed?

Or can I make this test work synchronously?