php - test unit in laravel

I have a update method with try catch exception, I wrote a test class but it doesn't cover the catch bloc,

public function update(Request $request, $id)
{
    $links= Link::find($id);
    if (empty($links)) {
        return \Response::json(["status" => "error", "errors" => "Not found"], HttpResponse::HTTP_NOT_FOUND);
    }
    try {
        $links= $links->update($request->all());
    } catch (\Exception $e) {
        return \Response::json(['status' => $e->getTraceAsString(), 'errors' => 'errors.ERROR_DATABASE_UPDATE'], HttpResponse::HTTP_INTERNAL_SERVER_ERROR);
    }
    return \Response::json(array('success' => true, 'link' => $links));
}
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the test class :

$response = $this->json('POST', '/links', [
            'title' => 'link1'])->seeStatusCode(200);

        $responseContent = json_decode($response->response->getContent());
        $this->assertEquals($responseContent->success, true);
        $linkToUpdate = $responseContent->link;
        $updatedTitle = $linkToUpdate ->title. "Updated";

        $responseUpdate = $this->json('PUT', '/links/' . $linkToUpdate->id, [
            'title' => $updatedTitle])->seeStatusCode(200);

        $responseContentUpdate = json_decode($responseUpdate->response->getContent());
        $this->assertEquals($responseContentUpdate->success, true);
    }
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But I don't cover the catch Exception bloc, how can i do it with my test class please ?