From 675d7732cd2051cae47ae543d77693675dbb9a9c Mon Sep 17 00:00:00 2001
From: Lukas Renggli <renggli@gmail.com>
Date: Mon, 18 Sep 2023 22:42:50 +0300
Subject: [PATCH] Fix the XPath `sum` function.

---
 lib/src/xpath/functions/number.dart | 6 +++---
 test/xpath_test.dart                | 2 ++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/src/xpath/functions/number.dart b/lib/src/xpath/functions/number.dart
index 2fe081f..b561b98 100644
--- a/lib/src/xpath/functions/number.dart
+++ b/lib/src/xpath/functions/number.dart
@@ -13,9 +13,9 @@ XPathValue number(XPathContext context, List<XPathExpression> arguments) {
 // number sum(node-set)
 XPathValue sum(XPathContext context, List<XPathExpression> arguments) {
   XPathEvaluationException.checkArgumentCount('sum', arguments, 1);
-  final nodes = arguments[0](context).nodes;
-  return XPathNumber(nodes
-      .map((node) => num.tryParse(node.toXmlString()) ?? 0)
+  return XPathNumber(arguments[0](context)
+      .nodes
+      .map((node) => num.tryParse(XPathNodeSet([node]).string) ?? 0)
       .fold(0, (a, b) => a + b));
 }
 
diff --git a/test/xpath_test.dart b/test/xpath_test.dart
index d389f90..9045f38 100644
--- a/test/xpath_test.dart
+++ b/test/xpath_test.dart
@@ -461,6 +461,8 @@ void main() {
       });
       test('sum', () {
         expectEvaluate(xml, 'sum(//text())', isNumber(6));
+        final attr = XmlDocument.parse('<r><e a="36"/><e a="6"/></r>');
+        expectEvaluate(attr, 'sum(/r/e/@a)', isNumber(42));
       });
       test('floor', () {
         expectEvaluate(xml, 'floor(-1.5)', isNumber(-2));