add another test case

transport_test.go

 package tcpreuse
 
 import (
+	"net"
 	"testing"
 
 	ma "github.com/multiformats/go-multiaddr"
 )
 
-func TestAll(t *testing.T) {
+func TestSingle(t *testing.T) {
 	var trA Transport
 	var trB Transport
 	laddr, _ := ma.NewMultiaddr("/ip4/127.0.0.1/tcp/0")
@@ -38,3 +39,48 @@ func TestAll(t *testing.T) {
 	<-done
 	c.Close()
 }
+
+func TestTwoLocal(t *testing.T) {
+	var trA Transport
+	var trB Transport
+	laddr, _ := ma.NewMultiaddr("/ip4/127.0.0.1/tcp/0")
+	listenerA, err := trA.Listen(laddr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listenerA.Close()
+
+	listenerB1, err := trB.Listen(laddr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listenerB1.Close()
+
+	listenerB2, err := trB.Listen(laddr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listenerB2.Close()
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		c, err := listenerA.Accept()
+		if err != nil {
+			t.Fatal(err)
+		}
+		c.Close()
+	}()
+
+	c, err := trB.Dial(listenerA.Multiaddr())
+	if err != nil {
+		t.Fatal(err)
+	}
+	localPort := c.LocalAddr().(*net.TCPAddr).Port
+	if localPort != listenerB1.Addr().(*net.TCPAddr).Port &&
+		localPort != listenerB2.Addr().(*net.TCPAddr).Port {
+		t.Fatal("didn't dial from one of our listener ports")
+	}
+	<-done
+	c.Close()
+}