Set EscapeMode=xhtml when OutputSettings.Syntax = XML

Was already configured when using the Parser.xmlParser(), but this will help users when parsing as HTML and then converting the output to XML.

CHANGES

@@ -6,6 +6,8 @@ Release 1.17.1 [PENDING]
     `#replaceAll(operator)`. These methods update the original DOM, as well as the Elements list.
     <https://github.com/jhy/jsoup/pull/2017>
 
+  * Improvement: when changing the OutputSettings syntax to XML, the xhtml EscapeMode is automatically set by default.
+
   * Bugfix: when outputting with XML syntax, HTML elements that were parsed as data nodes (<script> and <style>) should
     be emitted as CDATA nodes, so that they can be parsed correctly by an XML parser.
     <https://github.com/jhy/jsoup/pull/1720>

src/main/java/org/jsoup/nodes/Document.java

@@ -488,11 +488,15 @@ public Syntax syntax() {
         /**
          * Set the document's output syntax. Either {@code html}, with empty tags and boolean attributes (etc), or
          * {@code xml}, with self-closing tags.
+         * <p>When set to {@link Document.OutputSettings.Syntax#xml xml}, the {@link #escapeMode() escapeMode} is
+         * automatically set to {@link Entities.EscapeMode#xhtml}, but may be subsequently changed if desired.</p>
          * @param syntax serialization syntax
          * @return the document's output settings, for chaining
          */
         public OutputSettings syntax(Syntax syntax) {
             this.syntax = syntax;
+            if (syntax == Syntax.xml)
+                this.escapeMode(Entities.EscapeMode.xhtml);
             return this;
         }
 

src/test/java/org/jsoup/nodes/ElementTest.java

@@ -2838,4 +2838,19 @@ void prettySerializationRoundTrips(Document.OutputSettings settings) {
 
         assertEquals("<p>One</p>", header.html());
     }
+
+    @Test void xmlSyntaxSetsEscapeMode() {
+        String html = "Foo&nbsp;&Succeeds;";
+        Document doc = Jsoup.parse(html);
+        doc.outputSettings().charset("ascii"); // so we can see the zws
+        assertEquals("Foo&nbsp;&#x227b;", doc.body().html());
+
+        doc.outputSettings().syntax(Document.OutputSettings.Syntax.xml);
+        String out = doc.body().html();
+        assertEquals("Foo&#xa0;&#x227b;", out);
+
+        // can set back if desired
+        doc.outputSettings().escapeMode(Entities.EscapeMode.extended);
+        assertEquals("Foo&nbsp;&succ;", doc.body().html()); // succ is alias for Succeeds, and first hit in entities
+    }
 }