Handle nodes with multiple input handlers properly

Fixes #4330

packages/node_modules/@node-red/runtime/lib/nodes/Node.js

@@ -42,6 +42,7 @@ function Node(n) {
     this._closeCallbacks = [];
     this._inputCallback = null;
     this._inputCallbacks = null;
+    this._expectedDoneCount = 0;
 
     if (n.name) {
         this.name = n.name;
@@ -159,6 +160,9 @@ Node.prototype.on = function(event, callback) {
     if (event == "close") {
         this._closeCallbacks.push(callback);
     } else if (event === "input") {
+        if (callback.length === 3) {
+            this._expectedDoneCount++
+        }
         if (this._inputCallback) {
             this._inputCallbacks = [this._inputCallback, callback];
             this._inputCallback = null;
@@ -218,19 +222,17 @@ Node.prototype._emitInput = function(arg) {
             } else if (node._inputCallbacks) {
                 // Multiple callbacks registered. Call each one, tracking eventual completion
                 var c = node._inputCallbacks.length;
+                let doneCount = 0
                 for (var i=0;i<c;i++) {
                     var cb = node._inputCallbacks[i];
-                    if (cb.length === 2) {
-                        c++;
-                    }
                     try {
                         cb.call(
                             node,
                             arg,
                             function() { node.send.apply(node,arguments) },
                             function(err) {
-                                c--;
+                                doneCount++;
-                                if (c === 0) {
+                                if (doneCount === node._expectedDoneCount) {
                                     node._complete(arg,err);
                                 }
                             }
@@ -257,6 +259,9 @@ Node.prototype._removeListener = Node.prototype.removeListener;
 Node.prototype.removeListener = function(name, listener) {
     var index;
     if (name === "input") {
+        if (listener.length === 3) {
+            this._expectedDoneCount--
+        }
         if (this._inputCallback && this._inputCallback === listener) {
             // Removing the only callback
             this._inputCallback = null;

test/unit/@node-red/runtime/lib/nodes/Node_spec.js

@@ -183,6 +183,35 @@ describe('Node', function() {
             n.receive(message);
         });
 
+
+        it('calls parent flow handleComplete when multiple callbacks provided', function(done) {
+            var n = new RedNode({id:'123',type:'abc', _flow: {
+                handleComplete: function(node,msg) {
+                    try {
+                        doneCount.should.equal(2)
+                        msg.should.deepEqual(message);
+                        done();
+                    } catch(err) {
+                        done(err);
+                    }
+                }
+            }});
+
+            var message = {payload:"hello world"};
+            let doneCount = 0
+            n.on('input',function(msg, nodeSend, nodeDone) {
+                doneCount++
+                nodeDone();
+            });
+            // Include a callback without explicit done signature
+            n.on('input',function(msg) { });
+            n.on('input',function(msg, nodeSend, nodeDone) {
+                doneCount++
+                nodeDone();
+            });
+            n.receive(message);
+        });
+
         it('triggers onComplete hook when done callback provided', function(done) {
             var handleCompleteCalled = false;
             var hookCalled = false;