Fix #2422 - Cloned Parser does not reuse TagSet from original (#2423)

---------

Co-authored-by: Jonathan Hedley <jonathan@hedley.net>

Author: OlivierJaquemet

CHANGES.md

@@ -25,6 +25,7 @@
 * Null characters in the HTML body were not consistently removed; and in foreign content were not correctly replaced. [#2395](https://github.com/jhy/jsoup/issues/2395)
 * An IndexOutOfBoundsException could be thrown when parsing a body fragment with crafted input. Now logged as a parse error. [#2397](https://github.com/jhy/jsoup/issues/2397), [#2406](https://github.com/jhy/jsoup/issues/2406)
 * When using StructuralEvaluators (e.g., a `parent child` selector) across many retained threads, their memoized results could also be retained, increasing memory use. These results are now cleared immediately after use, reducing overall memory consumption. [#2411](https://github.com/jhy/jsoup/issues/2411)
+* Cloning a `Parser` now preserves any custom `TagSet` applied to the parser. [#2422](https://github.com/jhy/jsoup/issues/2422), [#2423](https://github.com/jhy/jsoup/pull/2423)
 * Custom tags marked as `Tag.Void` now parse and serialize like the built-in void elements: they no longer consume following content, and the XML serializer emits the expected self-closing form. [#2425](https://github.com/jhy/jsoup/issues/2425)
 
 ### Internal Changes

src/main/java/org/jsoup/parser/Parser.java

@@ -60,6 +60,7 @@ private Parser(Parser copy) {
         errors = new ParseErrorList(copy.errors); // only copies size, not contents
         settings = new ParseSettings(copy.settings);
         trackPosition = copy.trackPosition;
+        tagSet = new TagSet(copy.tagSet());
     }
 
     /**

src/main/java/org/jsoup/parser/TagSet.java

@@ -41,6 +41,8 @@ public TagSet() {
 
     public TagSet(TagSet original) {
         this.source = original;
+        if (original.customizers != null)
+            this.customizers = new ArrayList<>(original.customizers);
     }
 
     /**

src/test/java/org/jsoup/parser/ParserTest.java

@@ -9,7 +9,10 @@
 import java.nio.charset.StandardCharsets;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 public class ParserTest {
 
@@ -76,4 +79,24 @@ public void testClone() {
         assertEquals(xmlParser.settings().preserveTagCase(), xmlClone.settings().preserveTagCase());
         assertEquals(xmlParser.settings().preserveAttributeCase(), xmlClone.settings().preserveAttributeCase());
     }
+
+    @Test
+    public void testCloneCopyTagSet() {
+        Parser parser = Parser.htmlParser();
+        parser.tagSet().add(new Tag("foo"));
+        parser.tagSet().onNewTag(tag -> tag.set(Tag.SelfClose));
+        Parser clone = parser.clone();
+
+        // Ensure the tagsets are different instances
+        assertNotSame(clone.tagSet(), parser.tagSet());
+        // Check that cloned tagset contains same tag
+        assertNotNull(clone.tagSet().get("foo", Parser.NamespaceHtml));
+        // Ensure onNewTag customizers are retained
+        Tag custom = clone.tagSet().valueOf("qux", Parser.NamespaceHtml);
+        assertTrue(custom.isSelfClosing());
+        // Check that cloned tagset uses the original tag as source when original is modified
+        assertNull(clone.tagSet().get("bar", Parser.NamespaceHtml));
+        parser.tagSet().add(new Tag("bar"));
+        assertNotNull(clone.tagSet().get("bar", Parser.NamespaceHtml));
+    }
 }