From 5b0b27548ce5c5a7fffdceee23207598e7600d3e Mon Sep 17 00:00:00 2001
From: Arne Blankerts <Arne@Blankerts.de>
Date: Sun, 1 Nov 2020 00:47:48 +0100
Subject: [PATCH 1/2] Reimplement main aspect of assertEqualXMLStructure

---
 src/Framework/Assert.php           | 15 +++++++++++++++
 src/Framework/Assert/Functions.php | 17 +++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/Framework/Assert.php b/src/Framework/Assert.php
index 2e78802964e..bb32b9fba26 100644
--- a/src/Framework/Assert.php
+++ b/src/Framework/Assert.php
@@ -2251,6 +2251,21 @@ public static function assertXmlStringNotEqualsXmlString($expectedXml, $actualXm
         static::assertNotEquals($expected, $actual, $message);
     }
 
+    public static function assertDOMTreesEqualStructurally(DOMElement $expectedElement, DOMElement $actualElement, bool $keepComments = false, string $message = ''): void
+    {
+        $ed                     = new DOMDocument();
+        $ed->preserveWhiteSpace = false;
+        $ed->loadXML($expectedElement->C14N(false, $keepComments));
+        $ed->formatOutput = true;
+
+        $ad                     = new DOMDocument();
+        $ad->preserveWhiteSpace = false;
+        $ad->loadXML($actualElement->C14N(false, $keepComments));
+        $ad->formatOutput = true;
+
+        self::assertEquals($ed->documentElement, $ad->documentElement, $message);
+    }
+
     /**
      * Asserts that a hierarchy of DOMElements matches.
      *
diff --git a/src/Framework/Assert/Functions.php b/src/Framework/Assert/Functions.php
index 9363f4f7bc9..ee1f93ff3ab 100644
--- a/src/Framework/Assert/Functions.php
+++ b/src/Framework/Assert/Functions.php
@@ -2422,6 +2422,23 @@ function assertXmlStringNotEqualsXmlString($expectedXml, $actualXml, string $mes
     }
 }
 
+if (!function_exists('PHPUnit\Framework\assertDOMTreesEqualStructurally')) {
+    /**
+     * Asserts that two DOM trees are structurally identical.
+     *
+     * @throws AssertionFailedError
+     * @throws ExpectationFailedException
+     *
+     * @no-named-arguments Parameter names are not covered by the backward compatibility promise for PHPUnit
+     *
+     * @see Assert::assertDOMTreesEqualStructurally
+     */
+    function assertDOMTreesEqualStructurally(DOMElement $expectedElement, DOMElement $actualElement, bool $keepComments = false, string $message = ''): void
+    {
+        Assert::assertDOMTreesEqualStructurally(...func_get_args());
+    }
+}
+
 if (!function_exists('PHPUnit\Framework\assertEqualXMLStructure')) {
     /**
      * Asserts that a hierarchy of DOMElements matches.

From 85d4c053a8d0f6019bb70979b2d7e43cbddd99a8 Mon Sep 17 00:00:00 2001
From: Arne Blankerts <Arne@Blankerts.de>
Date: Sun, 1 Nov 2020 22:07:18 +0100
Subject: [PATCH 2/2] FIX: C14N doesn't work for non-rooted elements

---
 src/Framework/Assert.php | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/Framework/Assert.php b/src/Framework/Assert.php
index bb32b9fba26..b08c0b8c845 100644
--- a/src/Framework/Assert.php
+++ b/src/Framework/Assert.php
@@ -2253,14 +2253,20 @@ public static function assertXmlStringNotEqualsXmlString($expectedXml, $actualXm
 
     public static function assertDOMTreesEqualStructurally(DOMElement $expectedElement, DOMElement $actualElement, bool $keepComments = false, string $message = ''): void
     {
-        $ed                     = new DOMDocument();
+        $ed = new DOMDocument();
+        $ed->appendChild($ed->importNode($expectedElement, true));
+        $xmlStr = $ed->C14N(false, $keepComments);
+
         $ed->preserveWhiteSpace = false;
-        $ed->loadXML($expectedElement->C14N(false, $keepComments));
+        $ed->loadXML($xmlStr);
         $ed->formatOutput = true;
 
-        $ad                     = new DOMDocument();
+        $ad = new DOMDocument();
+        $ad->appendChild($ad->importNode($actualElement, true));
+        $xmlStr = $ad->C14N(false, $keepComments);
+
         $ad->preserveWhiteSpace = false;
-        $ad->loadXML($actualElement->C14N(false, $keepComments));
+        $ad->loadXML($xmlStr);
         $ad->formatOutput = true;
 
         self::assertEquals($ed->documentElement, $ad->documentElement, $message);