test: Add test for more than 32 connections (#93)

Making sure that this works on Windows after #88

Cargo.toml

@@ -49,3 +49,4 @@ features = [
 
 [dev-dependencies]
 easy-parallel = "3.1.0"
+fastrand = "1.9.0"

tests/many_connections.rs

@@ -0,0 +1,60 @@
+//! Tests to ensure more than 32 connections can be polled at once.
+
+// Doesn't work on OpenBSD.
+#![cfg(not(target_os = "openbsd"))]
+
+use std::io::{self, prelude::*};
+use std::net::{TcpListener, TcpStream};
+use std::time::Duration;
+
+#[test]
+fn many_connections() {
+    // Create 100 connections.
+    let mut connections = Vec::new();
+    for i in 0..100 {
+        let (reader, writer) = tcp_pair().unwrap();
+        connections.push((i, reader, writer));
+    }
+
+    // Create a poller and add all the connections.
+    let poller = polling::Poller::new().unwrap();
+
+    for (i, reader, _) in connections.iter() {
+        poller.add(reader, polling::Event::readable(*i)).unwrap();
+    }
+
+    let mut events = vec![];
+    while !connections.is_empty() {
+        // Choose a random connection to write to.
+        let i = fastrand::usize(..connections.len());
+        let (id, mut reader, mut writer) = connections.remove(i);
+
+        // Write a byte to the connection.
+        writer.write_all(&[1]).unwrap();
+
+        // Wait for the connection to become readable.
+        poller
+            .wait(&mut events, Some(Duration::from_secs(10)))
+            .unwrap();
+
+        // Check that the connection is readable.
+        assert_eq!(events.len(), 1, "events: {:?}", events);
+        assert_eq!(events[0].key, id);
+        assert!(events[0].readable);
+        assert!(!events[0].writable);
+
+        // Read the byte from the connection.
+        let mut buf = [0];
+        reader.read_exact(&mut buf).unwrap();
+        assert_eq!(buf, [1]);
+        poller.delete(&reader).unwrap();
+        events.clear();
+    }
+}
+
+fn tcp_pair() -> io::Result<(TcpStream, TcpStream)> {
+    let listener = TcpListener::bind("127.0.0.1:0")?;
+    let a = TcpStream::connect(listener.local_addr()?)?;
+    let (b, _) = listener.accept()?;
+    Ok((a, b))
+}