htlcswitch/mailbox_test: adds checks for reset and replay of pkts

htlcswitch/mailbox_test.go

@@ -25,6 +25,7 @@ func TestMailBoxCouriers(t *testing.T) {
 
 	// We'll be adding 10 message of both types to the mailbox.
 	const numPackets = 10
+	const halfPackets = numPackets / 2
 
 	// We'll add a set of random packets to the mailbox.
 	sentPackets := make([]*htlcPacket, numPackets)
@@ -96,4 +97,53 @@ func TestMailBoxCouriers(t *testing.T) {
 		t.Fatalf("recvd messages mismatched: expected %v, got %v",
 			spew.Sdump(sentMessages), spew.Sdump(recvdMessages))
 	}
+
+	// Now that we've received all of the intended msgs/pkts, ack back half
+	// of the packets.
+	for _, recvdPkt := range recvdPackets[:halfPackets] {
+		mailBox.AckPacket(recvdPkt.inKey())
+	}
+
+	// With the packets drained and partially acked,  we reset the mailbox,
+	// simulating a link shutting down and then coming back up.
+	mailBox.ResetMessages()
+	mailBox.ResetPackets()
+
+	// Now, we'll use the same alternating strategy to read from our
+	// mailbox. All wire messages are dropped on startup, but any unacked
+	// packets will be replayed in the same order they were delivered
+	// initially.
+	recvdPackets2 := make([]*htlcPacket, 0, halfPackets)
+	for i := 0; i < 2*halfPackets; i++ {
+		timeout := time.After(time.Second * 5)
+		if i%2 == 0 {
+			select {
+			case <-timeout:
+				t.Fatalf("didn't recv pkt after timeout")
+			case pkt := <-mailBox.PacketOutBox():
+				recvdPackets2 = append(recvdPackets2, pkt)
+			}
+		} else {
+			select {
+			case <-mailBox.MessageOutBox():
+				t.Fatalf("should not receive wire msg after reset")
+			default:
+			}
+		}
+	}
+
+	// The number of packets we received should match the number of unacked
+	// packets left in the mailbox.
+	if halfPackets != len(recvdPackets2) {
+		t.Fatalf("expected %v packets instead got %v", halfPackets,
+			len(recvdPackets))
+	}
+
+	// Additionally, the set of packets should match exactly with the
+	// unacked packets, and we should have received the packets in the exact
+	// same ordering that we added.
+	if !reflect.DeepEqual(recvdPackets[halfPackets:], recvdPackets2) {
+		t.Fatalf("recvd packets mismatched: expected %v, got %v",
+			spew.Sdump(sentPackets), spew.Sdump(recvdPackets))
+	}
 }