Add tests for new stat events

[josecelano]

New metrics have been added but some of them do not have a test.

A test for another event Event::Udp4Connect:

#[tokio::test]
async fn it_should_send_the_upd4_connect_event_when_a_client_tries_to_connect_using_a_ip4_socket_address() {
    let mut stats_event_sender_mock = statistics::event::sender::MockSender::new();
    stats_event_sender_mock
        .expect_send_event()
        .with(eq(statistics::event::Event::Udp4Connect))
        .times(1)
        .returning(|_| Box::pin(future::ready(Some(Ok(())))));
    let stats_event_sender = Box::new(stats_event_sender_mock);

    let client_socket_address = sample_ipv4_socket_address();

    let torrent_tracker = Arc::new(
        core::Tracker::new(
            &tracker_configuration().core,
            Some(stats_event_sender),
            statistics::repository::Repository::new(),
        )
        .unwrap(),
    );
    handle_connect(
        client_socket_address,
        &sample_connect_request(),
        &torrent_tracker,
        sample_issue_time(),
    )
    .await;
}

Only these events are covered:

• Udp4Connect
• Udp6Connect
• Udp4Announce
• Udp6Announce
• Udp4Scrape
• Udp6Scrape

And these are all the events:

pub enum Event {
    Tcp4Announce, // Covered
    Tcp4Scrape, // Covered
    Tcp6Announce, // Covered
    Tcp6Scrape, // Covered
    UdpRequestAborted,
    UdpRequestBanned,
    Udp4Request,
    Udp4Connect, // Covered
    Udp4Announce, // Covered
    Udp4Scrape, // Covered
    Udp4Response {
        kind: UdpResponseKind,
        req_processing_time: Duration,
    },
    Udp4Error,
    Udp6Request,
    Udp6Connect, // Covered
    Udp6Announce, // Covered
    Udp6Scrape, // Covered
    Udp6Response {
        kind: UdpResponseKind,
        req_processing_time: Duration,
    },
    Udp6Error,
}