From 3e4c45ac6a3cd67d2e8e00343ac5ac097a3b1774 Mon Sep 17 00:00:00 2001
From: Dave Conway-Jones <conway@uk.ibm.com>
Date: Thu, 22 Sep 2022 20:22:11 +0100
Subject: [PATCH] Fix change node overwriting msg with itself

and add test
to close #3891
---
 .../@node-red/nodes/core/function/15-change.js |  2 +-
 test/nodes/core/function/15-change_spec.js     | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/packages/node_modules/@node-red/nodes/core/function/15-change.js b/packages/node_modules/@node-red/nodes/core/function/15-change.js
index 94f47fcbf..ee0e8d9c7 100644
--- a/packages/node_modules/@node-red/nodes/core/function/15-change.js
+++ b/packages/node_modules/@node-red/nodes/core/function/15-change.js
@@ -318,7 +318,7 @@ module.exports = function(RED) {
             }
             var r = node.rules[currentRule];
             if (r.t === "move") {
-                if ((r.tot !== r.pt) || (r.p.indexOf(r.to) !== -1)) {
+                if ((r.tot !== r.pt) || (r.p.indexOf(r.to) !== -1) && (r.p !== r.to)) {
                     applyRule(msg,{t:"set", p:r.to, pt:r.tot, to:r.p, tot:r.pt},(err,msg) => {
                         applyRule(msg,{t:"delete", p:r.p, pt:r.pt}, (err,msg) => {
                             completeApplyingRules(msg,currentRule,done);
diff --git a/test/nodes/core/function/15-change_spec.js b/test/nodes/core/function/15-change_spec.js
index b8d7be03b..66f02d6d1 100644
--- a/test/nodes/core/function/15-change_spec.js
+++ b/test/nodes/core/function/15-change_spec.js
@@ -1717,6 +1717,24 @@ describe('change Node', function() {
                 changeNode1.receive({topic:{foo:{bar:1}}, payload:"String"});
             });
         });
+        it('moves the value of a message property object to itself', function(done) {
+            var flow = [{"id":"changeNode1","type":"change","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload","tot":"msg"}],"name":"changeNode","wires":[["helperNode1"]]},
+                        {id:"helperNode1", type:"helper", wires:[]}];
+            helper.load(changeNode, flow, function() {
+                var changeNode1 = helper.getNode("changeNode1");
+                var helperNode1 = helper.getNode("helperNode1");
+                helperNode1.on("input", function(msg) {
+                    try {
+                        msg.should.have.property('payload');
+                        msg.payload.should.equal("bar");
+                        done();
+                    } catch(err) {
+                        done(err);
+                    }
+                });
+                changeNode1.receive({payload:"bar"});
+            });
+        });
         it('moves the value of a message property object to a sub-property', function(done) {
             var flow = [{"id":"changeNode1","type":"change","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload.foo","tot":"msg"}],"name":"changeNode","wires":[["helperNode1"]]},
                         {id:"helperNode1", type:"helper", wires:[]}];