Add tcp peek test

Author: Darksonn

tests/tcp_stream.rs

@@ -876,3 +876,47 @@ fn send_oob_data<S: AsRawFd>(stream: &S, data: &[u8]) -> io::Result<usize> {
         }
     }
 }
+
+#[test]
+fn peek_readiness() {
+    let mut buf = [0; 1024];
+    let (mut poll, mut events) = init_with_poll();
+
+    let listener = net::TcpListener::bind(any_local_address()).unwrap();
+    let sockaddr = listener.local_addr().unwrap();
+    let thread_handle = thread::spawn(move || listener.accept().unwrap());
+    let mut stream1 = TcpStream::connect(sockaddr).unwrap();
+    let mut stream2 = thread_handle.join().unwrap();
+
+    stream1.set_nonblocking(true).unwrap();
+    let stream1 = TcpStream::from_std(stream1).unwrap();
+
+    poll.registry()
+        .register(&mut stream1, ID1, Interest::READABLE)
+        .unwrap();
+
+    expect_no_events(&mut poll, &mut events);
+    assert_would_block(stream1.peek(&mut buf));
+
+    assert_eq!(stream2.write(&[0]).unwrap(), 1);
+    expect_events(
+        &mut poll,
+        &mut events,
+        vec![ExpectEvent::new(ID1, Readiness::READABLE)],
+    );
+    assert_eq!(stream1.peek(&mut buf).unwrap(), 1);
+
+    assert_eq!(stream2.write(&[0]).unwrap(), 1);
+    expect_no_events(&mut poll, &mut events);
+    assert_eq!(stream1.peek(&mut buf).unwrap(), 2);
+    assert_eq!(stream1.read(&mut buf).unwrap(), 2);
+    assert_would_block(stream1.peek(&mut buf));
+
+    drop(stream2);
+    expect_events(
+        &mut poll,
+        &mut events,
+        vec![ExpectEvent::new(ID1, Readiness::READABLE)],
+    );
+    assert_eq!(stream1.peek(&mut buf).unwrap(), 0);
+}