Laravel 5: test return redirect with session

I have an insert method in Laravel, that return a message

if ($update === true) {
            return redirect(route('settings-cloudflare'))
                ->with('success', trans('common.operation_completed_successfully'));
            // validation ok
        } else {

How can I test that redirected view has "success" inside?

My test is:

    $response = $this->followingRedirects()->actingAs($user)->post(Route('settings-cloudflare-store'),$data);
    dd(session()->all());

But session doesn't have "success" inside.

Thank you very much

via Chebli Mohamed