tracker: Skip DNS error in UDP test

tracker/udp_test.go

@@ -125,27 +125,25 @@ func TestUDPTracker(t *testing.T) {
 	if testing.Short() {
 		t.SkipNow()
 	}
-	// if err := tr.Connect(); err != nil {
-	// 	if strings.Contains(err.Error(), "no such host") {
-	// 		t.Skip(err)
-	// 	}
-	// 	if strings.Contains(err.Error(), "i/o timeout") {
-	// 		t.Skip(err)
-	// 	}
-	// 	t.Fatal(err)
-	// }
 	req := AnnounceRequest{
 		NumWant: -1,
-		// Event:   Started,
 	}
 	rand.Read(req.PeerId[:])
 	copy(req.InfoHash[:], []uint8{0xa3, 0x56, 0x41, 0x43, 0x74, 0x23, 0xe6, 0x26, 0xd9, 0x38, 0x25, 0x4a, 0x6b, 0x80, 0x49, 0x10, 0xa6, 0x67, 0xa, 0xc1})
 	ar, err := Announce("udp://tracker.openbittorrent.com:80/announce", &req)
+	// Skip temporary errors as we don't control the server.
 	if ne, ok := err.(net.Error); ok {
 		if ne.Timeout() {
 			t.Skip(err)
 		}
 	}
+	// Skip DNS errors because the network might not be available, and we
+	// don't control the domains we're testing.
+	if oe, ok := err.(*net.OpError); ok {
+		if _, ok := oe.Err.(*net.DNSError); ok {
+			t.Skip(err)
+		}
+	}
 	require.NoError(t, err)
 	t.Log(ar)
 }