From 35430d09ed8bc9ddd7a12635450514d1bbe7352f Mon Sep 17 00:00:00 2001
From: "jeremy@jermolene.com" <jeremy@jermolene.com>
Date: Thu, 5 May 2022 08:16:20 +0100
Subject: [PATCH] Fix bug with empty strings ignored in
 $tw.utils.stringifyList/parseStringArray

I will pull this out into a separate PR. Fixing it doesn't cause problems for the core but I imagine it might cause issues for 3rd party code.
---
 boot/boot.js                               | 4 ++--
 editions/test/tiddlers/tests/test-utils.js | 4 +++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/boot/boot.js b/boot/boot.js
index f902e9956..4bdedf4ef 100644
--- a/boot/boot.js
+++ b/boot/boot.js
@@ -375,7 +375,7 @@ $tw.utils.stringifyList = function(value) {
 		var result = new Array(value.length);
 		for(var t=0, l=value.length; t<l; t++) {
 			var entry = value[t] || "";
-			if(entry.indexOf(" ") !== -1) {
+			if(entry.indexOf(" ") !== -1 || entry === "") {
 				result[t] = "[[" + entry + "]]";
 			} else {
 				result[t] = entry;
@@ -396,7 +396,7 @@ $tw.utils.parseStringArray = function(value, allowDuplicate) {
 		do {
 			match = memberRegExp.exec(value);
 			if(match) {
-				var item = match[1] || match[2];
+				var item = match[1] !== undefined ? match[1] : match[2];
 				if(item !== undefined && (!$tw.utils.hop(names,item) || allowDuplicate)) {
 					results.push(item);
 					names[item] = true;
diff --git a/editions/test/tiddlers/tests/test-utils.js b/editions/test/tiddlers/tests/test-utils.js
index 9af127965..2714a43be 100644
--- a/editions/test/tiddlers/tests/test-utils.js
+++ b/editions/test/tiddlers/tests/test-utils.js
@@ -20,6 +20,7 @@ describe("Utility tests", function() {
 		expect(psa(" Tiddler8")).toEqual(["Tiddler8"]);
 		expect(psa("Tiddler8 ")).toEqual(["Tiddler8"]);
 		expect(psa("Tiddler8 two")).toEqual(["Tiddler8","two"]);
+		expect(psa("Tiddler8 two [[]]")).toEqual(["Tiddler8","two",""]);
 		expect(psa(" Tiddler8 two ")).toEqual(["Tiddler8","two"]);
 		expect(psa(" Tidd\u00a0ler8 two ")).toEqual(["Tidd\u00a0ler8","two"]);
 		expect(psa(" [[Tidd\u00a0ler8]] two ")).toEqual(["Tidd\u00a0ler8","two"]);
@@ -51,6 +52,7 @@ describe("Utility tests", function() {
 	it("should handle stringifying a string array", function() {
 		var str = $tw.utils.stringifyList;
 		expect(str([])).toEqual("");
+		expect(str([""])).toEqual("[[]]");
 		expect(str(["Tiddler8"])).toEqual("Tiddler8");
 		expect(str(["Tiddler8  "])).toEqual("[[Tiddler8  ]]");
 		expect(str(["A+B", "A-B", "A=B"])).toEqual("A+B A-B A=B");
@@ -58,7 +60,7 @@ describe("Utility tests", function() {
 		// Starting special characters aren't treated specially,
 		// even though this makes a list incompatible with a filter parser.
 		expect(str(["+T", "-T", "~T", "=T", "$T"])).toEqual("+T -T ~T =T $T");
-		expect(str(["A", "", "B"])).toEqual("A  B");
+		expect(str(["A", "", "B"])).toEqual("A [[]] B");
 	});
 
 	it("stringifyList shouldn't interfere with setting variables to negative numbers", function() {