test: followup update chainnotifier mock to fwd notifications for matching txs

This is the remainder of the previous commit which was left out from the
original PR.

test/chainnotifier_mock.go

@@ -12,8 +12,10 @@ import (
 )
 
 type mockChainNotifier struct {
-	lnd *LndMockServices
-	wg  sync.WaitGroup
+	sync.Mutex
+	lnd               *LndMockServices
+	confRegistrations []*ConfRegistration
+	wg                sync.WaitGroup
 }
 
 // SpendRegistration contains registration details.
@@ -29,6 +31,7 @@ type ConfRegistration struct {
 	PkScript   []byte
 	HeightHint int32
 	NumConfs   int32
+	ConfChan   chan *chainntnfs.TxConfirmation
 }
 
 func (c *mockChainNotifier) RegisterSpendNtfn(ctx context.Context,
@@ -103,7 +106,18 @@ func (c *mockChainNotifier) RegisterConfirmationsNtfn(ctx context.Context,
 	txid *chainhash.Hash, pkScript []byte, numConfs, heightHint int32) (
 	chan *chainntnfs.TxConfirmation, chan error, error) {
 
-	confChan := make(chan *chainntnfs.TxConfirmation, 1)
+	reg := &ConfRegistration{
+		PkScript:   pkScript,
+		TxID:       txid,
+		HeightHint: heightHint,
+		NumConfs:   numConfs,
+		ConfChan:   make(chan *chainntnfs.TxConfirmation, 1),
+	}
+
+	c.Lock()
+	c.confRegistrations = append(c.confRegistrations, reg)
+	c.Unlock()
+
 	errChan := make(chan error, 1)
 
 	c.wg.Add(1)
@@ -112,26 +126,35 @@ func (c *mockChainNotifier) RegisterConfirmationsNtfn(ctx context.Context,
 
 		select {
 		case m := <-c.lnd.ConfChannel:
-			if bytes.Equal(m.Tx.TxOut[0].PkScript, pkScript) {
-				select {
-				case confChan <- m:
-				case <-ctx.Done():
+			c.Lock()
+			for i := 0; i < len(c.confRegistrations); i++ {
+				r := c.confRegistrations[i]
+
+				// Whichever conf notifier catches the confirmation
+				// will forward it to all matching subscibers.
+				if bytes.Equal(m.Tx.TxOut[0].PkScript, r.PkScript) {
+					// Unregister the "notifier".
+					c.confRegistrations = append(
+						c.confRegistrations[:i], c.confRegistrations[i+1:]...,
+					)
+					i--
+
+					select {
+					case r.ConfChan <- m:
+					case <-ctx.Done():
+					}
 				}
 			}
+			c.Unlock()
 		case <-ctx.Done():
 		}
 	}()
 
 	select {
-	case c.lnd.RegisterConfChannel <- &ConfRegistration{
-		PkScript:   pkScript,
-		TxID:       txid,
-		HeightHint: heightHint,
-		NumConfs:   numConfs,
-	}:
+	case c.lnd.RegisterConfChannel <- reg:
 	case <-time.After(Timeout):
 		return nil, nil, ErrTimeout
 	}
 
-	return confChan, errChan, nil
+	return reg.ConfChan, errChan, nil
 }