refactor!: Avoid empty namespace value like xmlns:ds="" (#168)

* X3-88886: Signed Facturae XML not validated

* avoid empty namespace url

* avoid empty namespace url

* avoid empty namespace url

* Add test for prefixed xml tag without namespace

Co-authored-by: Franck Depoortere <franck.depoortere@sage.com>
Co-authored-by: Eric Boureau <eric.boureau@sage.com>
Co-authored-by: Christopher J. Brody <chris.brody+brodybits@gmail.com>

lib/dom.js

@@ -1024,9 +1024,13 @@ function serializeToString(node,buf,isHTML,nodeFilter,visibleNamespaces){
 		if (needNamespaceDefine(node,isHTML, visibleNamespaces)) {
 			var prefix = node.prefix||'';
 			var uri = node.namespaceURI;
-			var ns = prefix ? ' xmlns:' + prefix : " xmlns";
-			buf.push(ns, '="' , uri , '"');
-			visibleNamespaces.push({ prefix: prefix, namespace:uri });
+			if (uri) {
+				// Avoid empty namespace value like xmlns:ds=""
+				// Empty namespace URL will we produce an invalid XML document
+				var ns = prefix ? ' xmlns:' + prefix : " xmlns";
+				buf.push(ns, '="' , uri , '"');
+				visibleNamespaces.push({ prefix: prefix, namespace:uri });
+			}
 		}
 
 		if(child || isHTML && !/^(?:meta|link|img|br|hr|input)$/i.test(nodeName)){

test/parse/node.test.js

@@ -87,6 +87,20 @@ describe('XML Node Parse', () => {
 		})
 	})
 
+	it('prefixed without empty namespace', () => {
+		const source = '<w:p><w:r>test1</w:r><w:r>test2</w:r></w:p>'
+		const { documentElement } = new DOMParser().parseFromString(source)
+
+		expect(documentElement.firstChild.firstChild).toMatchObject({
+			nodeValue: 'test1',
+		})
+		expect(documentElement.lastChild.firstChild).toMatchObject({
+			nodeValue: 'test2',
+		})
+
+		expect(documentElement.toString()).toStrictEqual(source)
+	})
+
 	it('cdata comment', () => {
 		const { documentElement } = new DOMParser().parseFromString(
 			'<xml>start <![CDATA[<encoded>]]> <!-- comment -->end</xml>'