improve performance of EqualToXmlPattern. (#2944)

RafeArnold · web-flow · commit 9ccb1c89a3f1 · 2025-01-30T13:13:01.000Z
removes use of DiffBuilder.ignoreComments which performs an xslt
transform on the provided XML documents which is very memory intensive.
now comments are ignored at read/parse time.

as part of this change, the Xml utility class was also refactored to
(hopefully) make it more reusable.
diff --git a/src/main/java/com/github/tomakehurst/wiremock/matching/EqualToXmlPattern.java b/src/main/java/com/github/tomakehurst/wiremock/matching/EqualToXmlPattern.java
@@ -151,7 +151,6 @@ public boolean isExactMatch() {
                   .withTest(value)
                   .withComparisonController(ComparisonControllers.StopWhenDifferent)
                   .ignoreWhitespace()
-                  .ignoreComments()
                   .withDifferenceEvaluator(diffEvaluator)
                   .withNodeMatcher(new OrderInvariantNodeMatcher(ignoreOrderOfSameNode))
                   .withDocumentBuilderFactory(DOCUMENT_BUILDER_FACTORY)
@@ -188,7 +187,6 @@ public double getDistance() {
               DiffBuilder.compare(Input.from(expectedValue))
                   .withTest(value)
                   .ignoreWhitespace()
-                  .ignoreComments()
                   .withDifferenceEvaluator(diffEvaluator)
                   .withComparisonListeners(
                       (comparison, outcome) -> {
@@ -228,6 +226,7 @@ public double getDistance() {
   private static DocumentBuilderFactory newDocumentBuilderFactory() {
     DocumentBuilderFactory factory = Xml.newDocumentBuilderFactory();
     try {
+      factory.setFeature("http://apache.org/xml/features/include-comments", false);
       factory.setFeature("http://xml.org/sax/features/namespaces", true);
     } catch (ParserConfigurationException e) {
       throwUnchecked(e);
diff --git a/src/test/java/com/github/tomakehurst/wiremock/matching/EqualToXmlPatternTest.java b/src/test/java/com/github/tomakehurst/wiremock/matching/EqualToXmlPatternTest.java
@@ -568,4 +568,12 @@ void matchesIfTwoIdenticalChildNodesAreEmpty() {
     MatchResult result = pattern.match("<body><entry/><entry/></body>");
     assertTrue(result.isExactMatch());
   }
+
+  @Test
+  void matchesIfCommentsDiffer() {
+    EqualToXmlPattern pattern =
+        new EqualToXmlPattern("<body><!-- Comment --><entry/><entry/></body>", false, true);
+    MatchResult result = pattern.match("<body><entry/><entry/><!-- A different comment --></body>");
+    assertTrue(result.isExactMatch());
+  }
 }

Original file line number	Diff line number	Diff line change
`@@ -568,4 +568,12 @@ void matchesIfTwoIdenticalChildNodesAreEmpty() {`
`568`	`568`	`MatchResult result = pattern.match("<body><entry/><entry/></body>");`
`569`	`569`	`assertTrue(result.isExactMatch());`
`570`	`570`	`}`
	`571`	`+`
	`572`	`+ @Test`
	`573`	`+ void matchesIfCommentsDiffer() {`
	`574`	`+ EqualToXmlPattern pattern =`
	`575`	`+ new EqualToXmlPattern("<body><!-- Comment --><entry/><entry/></body>", false, true);`
	`576`	`+ MatchResult result = pattern.match("<body><entry/><entry/><!-- A different comment --></body>");`
	`577`	`+ assertTrue(result.isExactMatch());`
	`578`	`+ }`
`571`	`579`	`}`