chainntfns: add new option for conf notifications to send block

In this commit, we add a new option for the existing confirmation
notification system that optionally allows the caller to specify that a
block should be included as well.

The only quirk w/ the implementation here is the neutrino backend:
usually we get filtered blocks, we so need to first fetch the block
again so we can deliver the full block to the notifier. On the notifier
end, it'll only be checking for the transactions we care about, to
sending a full block doesn't affect the correctness.

We also extend the `testBatchConfirmationNotification` test to assert
that a block is only included if the caller specifies it.

chainntnfs/test/test_interface.go

@@ -160,6 +160,13 @@ func testBatchConfirmationNotification(miner *rpctest.Harness,
 	// verify they're each notified at the proper number of confirmations
 	// below.
 	for i, numConfs := range confSpread {
+		// All the clients with an even index will ask for the block
+		// along side the conf ntfn.
+		var opts []chainntnfs.NotifierOption
+		if i%2 == 0 {
+			opts = append(opts, chainntnfs.WithIncludeBlock())
+		}
+
 		txid, pkScript, err := chainntnfs.GetTestTxidAndScript(miner)
 		if err != nil {
 			t.Fatalf("unable to create test addr: %v", err)
@@ -168,10 +175,12 @@ func testBatchConfirmationNotification(miner *rpctest.Harness,
 		if scriptDispatch {
 			confIntent, err = notifier.RegisterConfirmationsNtfn(
 				nil, pkScript, numConfs, uint32(currentHeight),
+				opts...,
 			)
 		} else {
 			confIntent, err = notifier.RegisterConfirmationsNtfn(
 				txid, pkScript, numConfs, uint32(currentHeight),
+				opts...,
 			)
 		}
 		if err != nil {
@@ -218,6 +227,12 @@ func testBatchConfirmationNotification(miner *rpctest.Harness,
 					"conf height: expected %v, got %v",
 					initialConfHeight, conf.BlockHeight)
 			}
+
+			// If this is an even client index, then we expect the
+			// block to be populated. Otherwise, it should be
+			// empty.
+			expectBlock := i%2 == 0
+			require.Equal(t, expectBlock, conf.Block != nil)
 			continue
 		case <-time.After(20 * time.Second):
 			t.Fatalf("confirmation notification never received: %v", numConfs)
@@ -547,6 +562,7 @@ func testTxConfirmedBeforeNtfnRegistration(miner *rpctest.Harness,
 	if scriptDispatch {
 		ntfn1, err = notifier.RegisterConfirmationsNtfn(
 			nil, pkScript1, 1, uint32(currentHeight),
+			chainntnfs.WithIncludeBlock(),
 		)
 	} else {
 		ntfn1, err = notifier.RegisterConfirmationsNtfn(
@@ -579,6 +595,13 @@ func testTxConfirmedBeforeNtfnRegistration(miner *rpctest.Harness,
 			t.Fatalf("incorrect block height: expected %v, got %v",
 				confInfo.BlockHeight, currentHeight)
 		}
+
+		// Ensure that if this was a script dispatch, the block is set
+		// as well.
+		if scriptDispatch {
+			require.NotNil(t, confInfo.Block)
+		}
+
 		break
 	case <-time.After(20 * time.Second):
 		t.Fatalf("confirmation notification never received")
@@ -591,6 +614,7 @@ func testTxConfirmedBeforeNtfnRegistration(miner *rpctest.Harness,
 	if scriptDispatch {
 		ntfn2, err = notifier.RegisterConfirmationsNtfn(
 			nil, pkScript2, 3, uint32(currentHeight),
+			chainntnfs.WithIncludeBlock(),
 		)
 	} else {
 		ntfn2, err = notifier.RegisterConfirmationsNtfn(
@@ -622,6 +646,7 @@ func testTxConfirmedBeforeNtfnRegistration(miner *rpctest.Harness,
 	if scriptDispatch {
 		ntfn3, err = notifier.RegisterConfirmationsNtfn(
 			nil, pkScript3, 1, uint32(currentHeight-1),
+			chainntnfs.WithIncludeBlock(),
 		)
 	} else {
 		ntfn3, err = notifier.RegisterConfirmationsNtfn(
@@ -640,7 +665,10 @@ func testTxConfirmedBeforeNtfnRegistration(miner *rpctest.Harness,
 	require.NoError(t, err, "unable to register ntfn")
 
 	select {
-	case <-ntfn3.Confirmed:
+	case confInfo := <-ntfn3.Confirmed:
+		if scriptDispatch {
+			require.NotNil(t, confInfo.Block)
+		}
 	case <-time.After(10 * time.Second):
 		t.Fatalf("confirmation notification never received")
 	}