HtmlUnit · chiliec · Sep 20, 2026 · Sep 24, 2026
diff --git a/pom.xml b/pom.xml
@@ -1423,6 +1423,10 @@
             <name>MatrixNeoKozak</name>
             <email>matrixneo2026@tutamail.com</email>
         </contributor>
+        <contributor>
+            <name>Vladimir Babin</name>
+            <email>vovababin@gmail.com</email>
+        </contributor>
     </contributors>
     <dependencies>
         <!-- this includes httpclient as dependency -->

diff --git a/src/changes/changes.xml b/src/changes/changes.xml
@@ -8,6 +8,9 @@
 
     <body>
         <release version="5.6.0" date="September xx, 2026" description="Chrome/Edge 153, Bugfixes">
+            <action type="add" dev="rbri" due-to="Vladimir Babin" issue="#91">
+                MockWebConnection is now Serializable.
+            </action>
             <action type="update" dev="rbri">
                 websocket-client: jetty updated to 12.1.13.
             </action>
@@ -14230,7 +14233,7 @@
             <action type="fix" dev="asashour" issue="470" due-to="Bruce Chapman">
                 HtmlPage.clone() doesn't share idMap_ with original (#1708397).
             </action>
-            <action type="add" dev="asashour" issue="91" system="features">
+            <action type="add" dev="asashour" issue="#91" system="features">
                 ClickableElement: Add dblClick() (#1385295).
             </action>
             <action type="add" dev="asashour" issue="364">

diff --git a/src/main/java/org/htmlunit/MockWebConnection.java b/src/main/java/org/htmlunit/MockWebConnection.java
@@ -17,6 +17,9 @@
 import static java.nio.charset.StandardCharsets.ISO_8859_1;
 
 import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
 import java.net.URL;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
@@ -42,7 +45,7 @@
  * @author Ahmed Ashour
  * @author Ronald Brill
  */
-public class MockWebConnection implements WebConnection {
+public class MockWebConnection implements WebConnection, Serializable {
 
     private static final Log LOG = LogFactory.getLog(MockWebConnection.class);
 
@@ -56,13 +59,13 @@ public class MockWebConnection implements WebConnection {
     /**
      * Contains the raw data configured for a response.
      */
-    public static class RawResponseData {
+    public static class RawResponseData implements Serializable {
         private final List<NameValuePair> headers_;
         private final byte[] byteContent_;
         private final String stringContent_;
         private final int statusCode_;
         private final String statusMessage_;
-        private final Charset charset_;
+        private transient Charset charset_;
 
         RawResponseData(final byte[] byteContent, final int statusCode, final String statusMessage,
                 final String contentType, final List<NameValuePair> headers) {
@@ -162,6 +165,19 @@ public String getStatusMessage() {
         public Charset getCharset() {
             return charset_;
         }
+
+        private void writeObject(final ObjectOutputStream oos) throws IOException {
+            oos.defaultWriteObject();
+            oos.writeObject(charset_ == null ? null : charset_.name());
+        }
+
+        private void readObject(final ObjectInputStream ois) throws ClassNotFoundException, IOException {
+            ois.defaultReadObject();
+            final String charsetName = (String) ois.readObject();
+            if (charsetName != null) {
+                charset_ = Charset.forName(charsetName);
+            }
+        }
     }
 
     /**

diff --git a/src/test/java/org/htmlunit/MockWebConnectionTest.java b/src/test/java/org/htmlunit/MockWebConnectionTest.java
@@ -15,7 +15,14 @@
 package org.htmlunit;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.fail;
 
+import java.io.IOException;
+import java.net.URL;
+import java.util.Collections;
+
+import org.apache.commons.io.IOUtils;
 import org.htmlunit.html.HtmlPage;
 import org.htmlunit.util.MimeType;
 import org.junit.jupiter.api.Test;
@@ -49,4 +56,58 @@ public void charset() throws Exception {
         final HtmlPage page = client.getPage(URL_FIRST);
         assertEquals("\u00A3", page.getBody().asNormalizedText());
     }
+
+    /**
+     * @throws Exception if an error occurs
+     */
+    @Test
+    public void serialization() throws Exception {
+        final String html = DOCTYPE_HTML
+            + "<html>\n"
+            + "<head>\n"
+            + "  <meta http-equiv='Content-Type' content='text/html; charset=UTF-8'/>\n"
+            + "  <title>Serialized</title>\n"
+            + "</head>\n"
+            + "<body>\u00A3</body>\n"
+            + "</html>";
+
+        final MockWebConnection webConnection = new MockWebConnection();
+        webConnection.setResponse(URL_FIRST, html, MimeType.TEXT_HTML, UTF_8);
+        webConnection.setResponse(URL_SECOND, new byte[] {1, 2, 3}, 404, "Not Found",
+                MimeType.APPLICATION_OCTET_STREAM, null);
+        webConnection.setDefaultResponse("default");
+        webConnection.setThrowable(URL_THIRD, new IOException("boom"));
+
+        final WebClient client = getWebClient();
+        client.setWebConnection(webConnection);
+        client.getPage(URL_FIRST);
+
+        final MockWebConnection copy = clone(webConnection);
+
+        assertEquals(1, copy.getRequestCount());
+        assertEquals(Collections.singletonList(URL_FIRST), copy.getRequestedUrls());
+        assertEquals(URL_FIRST, copy.getLastWebRequest().getUrl());
+
+        client.setWebConnection(copy);
+        final HtmlPage page = client.getPage(URL_FIRST);
+        assertEquals("\u00A3", page.getBody().asNormalizedText());
+        assertEquals("Serialized", page.getTitleText());
+
+        final WebResponse second = copy.getResponse(new WebRequest(URL_SECOND));
+        assertEquals(404, second.getStatusCode());
+        assertEquals("Not Found", second.getStatusMessage());
+        assertArrayEquals(new byte[] {1, 2, 3}, IOUtils.toByteArray(second.getContentAsStream()));
+
+        final WebResponse other = copy.getResponse(new WebRequest(new URL("http://localhost/other")));
+        assertEquals("default", other.getContentAsString());
+
+        try {
+            copy.getResponse(new WebRequest(URL_THIRD));
+            fail("IOException expected");
+        }
+        catch (final IOException e) {
+            assertEquals("boom", e.getMessage());
+        }
+        assertEquals(5, copy.getRequestCount());
+    }
 }