Factor out TestServer. (#98)

This creates a struct that encapsulates the test server setup, and adds
a shutdown method to clean up the thread when done.

src/test/testserver.rs

@@ -0,0 +1,50 @@
+use std::io::{self, BufRead, BufReader};
+use std::net::{TcpListener, TcpStream};
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
+use std::thread;
+
+pub struct TestServer {
+    pub port: u16,
+    pub done: Arc<AtomicBool>,
+}
+
+// Read a stream until reaching a blank line, in order to consume
+// request headers.
+pub fn read_headers(stream: &TcpStream) {
+    for line in BufReader::new(stream).lines() {
+        if line.unwrap() == "" {
+            break;
+        }
+    }
+}
+
+impl TestServer {
+    pub fn new(handler: fn(TcpStream) -> io::Result<()>) -> Self {
+        let listener = TcpListener::bind("localhost:0").unwrap();
+        let port = listener.local_addr().unwrap().port();
+        let done = Arc::new(AtomicBool::new(false));
+        let done_clone = done.clone();
+        thread::spawn(move || {
+            for stream in listener.incoming() {
+                thread::spawn(move || handler(stream.unwrap()));
+                if done.load(Ordering::Relaxed) {
+                    break;
+                }
+            }
+            println!("testserver on {} exiting", port);
+        });
+        TestServer {
+            port,
+            done: done_clone,
+        }
+    }
+}
+
+impl Drop for TestServer {
+    fn drop(&mut self) {
+        self.done.store(true, Ordering::Relaxed);
+        // Connect once to unblock the listen loop.
+        TcpStream::connect(format!("localhost:{}", self.port)).unwrap();
+    }
+}