GuzzleHttp\Test\Handler\StreamHandlerTest::testRejectsPromiseWhenOnHeadersFails PHP Method

    public function testRejectsPromiseWhenOnHeadersFails()
    {
        Server::flush();
        Server::enqueue([new Response(200, ['X-Foo' => 'bar'], 'abc 123')]);
        $req = new Request('GET', Server::$url);
        $handler = new StreamHandler();
        $promise = $handler($req, ['on_headers' => function () {
            throw new \Exception('test');
        }]);
        $promise->wait();
    }