package net

// Regression: a fatal transport failure (a listener that cannot bind, an
// Accept loop that dies outside shutdown) must unblock ListenAndServe with
// the error — a server must never sit running with no way in — and a
// failure followed by Shutdown must not panic on a double close of done.

import (
	"fmt"
	"net"
	"net/http"
	"testing"
	"time"
)

func TestTransportFailureStopsListenAndServe(t *testing.T) {
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()
	port := fmt.Sprintf("127.0.0.1:%d", ln.Addr().(*net.TCPAddr).Port)

	s := &Server{hub: NewHub(), done: make(chan struct{})}
	s.httpServer = &http.Server{Addr: port, Handler: http.NewServeMux()}

	result := make(chan error, 1)
	go func() {
		go s.serveHTTP()
		<-s.done
		result <- s.listenErr
	}()

	select {
	case err := <-result:
		if err == nil {
			t.Fatal("transport failure unblocked ListenAndServe without an error")
		}
		// Shutdown after a failure must not double-close done.
		s.Shutdown()
	case <-time.After(2 * time.Second):
		t.Fatal("a failed listener left the server running")
	}
}