Fix for zero values interpreted as empty (spatie#112)

Author: vdbelt

src/ArrayToXml.php

@@ -168,7 +168,7 @@ protected function addCollectionNode(DOMElement $element, $value)
 
     protected function addSequentialNode(DOMElement $element, $value)
     {
-        if (empty($element->nodeValue)) {
+        if (empty($element->nodeValue) && ! is_numeric($element->nodeValue)) {
             $element->nodeValue = htmlspecialchars($value);
 
             return;

tests/ArrayToXmlTest.php

@@ -106,6 +106,14 @@ public function it_can_handle_values_as_basic_collection()
         ]));
     }
 
+    /** @test */
+    public function it_can_handle_zero_values_in_beginning_of_basic_collection()
+    {
+        $this->assertMatchesXmlSnapshot(ArrayToXml::convert([
+            'user' => ['0', '1', '0'],
+        ]));
+    }
+
     /** @test */
     public function it_accepts_an_xml_encoding_type()
     {

tests/__snapshots__/ArrayToXmlTest__it_can_handle_zero_values_in_beginning_of_basic_collection__1.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<root>
+  <user>0</user>
+  <user>1</user>
+  <user>0</user>
+</root>