add serialization test

src/test/java/com/fasterxml/jackson/core/JDKSerializabilityTest.java

@@ -9,6 +9,8 @@
 import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
 import com.fasterxml.jackson.core.util.JsonRecyclerPools;
 
+import static com.fasterxml.jackson.core.util.JdkSerializationTestUtils.jdkDeserialize;
+import static com.fasterxml.jackson.core.util.JdkSerializationTestUtils.jdkSerialize;
 import static org.junit.jupiter.api.Assertions.*;
 
 /**
@@ -259,29 +261,6 @@ void pointerSerializationEmpty() throws Exception
     /**********************************************************
      */
 
-    protected byte[] jdkSerialize(Object o) throws IOException
-    {
-        ByteArrayOutputStream bytes = new ByteArrayOutputStream(1000);
-        ObjectOutputStream obOut = new ObjectOutputStream(bytes);
-        obOut.writeObject(o);
-        obOut.close();
-        return bytes.toByteArray();
-    }
-
-    @SuppressWarnings("unchecked")
-    protected <T> T jdkDeserialize(byte[] raw) throws IOException
-    {
-        ObjectInputStream objIn = new ObjectInputStream(new ByteArrayInputStream(raw));
-        try {
-            return (T) objIn.readObject();
-        } catch (ClassNotFoundException e) {
-            fail("Missing class: "+e.getMessage());
-            return null;
-        } finally {
-            objIn.close();
-        }
-    }
-
     @SuppressWarnings("resource")
     protected String _copyJson(JsonFactory f, String json, boolean useBytes) throws IOException
     {

src/test/java/com/fasterxml/jackson/core/util/JdkSerializationTestUtils.java

@@ -0,0 +1,34 @@
+package com.fasterxml.jackson.core.util;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+
+import static org.junit.jupiter.api.Assertions.fail;
+
+public class JdkSerializationTestUtils {
+    public static byte[] jdkSerialize(Object o) throws IOException
+    {
+        ByteArrayOutputStream bytes = new ByteArrayOutputStream(1000);
+        ObjectOutputStream obOut = new ObjectOutputStream(bytes);
+        obOut.writeObject(o);
+        obOut.close();
+        return bytes.toByteArray();
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> T jdkDeserialize(byte[] raw) throws IOException
+    {
+        ObjectInputStream objIn = new ObjectInputStream(new ByteArrayInputStream(raw));
+        try {
+            return (T) objIn.readObject();
+        } catch (ClassNotFoundException e) {
+            fail("Missing class: "+e.getMessage());
+            return null;
+        } finally {
+            objIn.close();
+        }
+    }
+}

src/test/java/com/fasterxml/jackson/core/util/TestSerializedString.java

@@ -9,6 +9,8 @@
 import org.junit.jupiter.api.Test;
 import com.fasterxml.jackson.core.io.SerializedString;
 
+import static com.fasterxml.jackson.core.util.JdkSerializationTestUtils.jdkDeserialize;
+import static com.fasterxml.jackson.core.util.JdkSerializationTestUtils.jdkSerialize;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
@@ -18,11 +20,12 @@
 class TestSerializedString
         extends com.fasterxml.jackson.core.JUnit5TestBase
 {
+    private static final String QUOTED = "\\\"quo\\\\ted\\\"";
+
     @Test
     void appending() throws IOException
     {
         final String INPUT = "\"quo\\ted\"";
-        final String QUOTED = "\\\"quo\\\\ted\\\"";
 
         SerializableString sstr = new SerializedString(INPUT);
         // sanity checks first:
@@ -63,4 +66,23 @@ void failedAccess() throws IOException
         assertEquals(-1, sstr.appendUnquoted(ch, 0));
         assertEquals(-1, sstr.putUnquotedUTF8(bbuf));
     }
+
+    @Test
+    void testAppendQuotedUTF8() throws IOException {
+        SerializedString sstr = new SerializedString(QUOTED);
+        assertEquals(QUOTED, sstr.getValue());
+        final byte[] buffer = new byte[100];
+        final int len = sstr.appendQuotedUTF8(buffer, 3);
+        assertEquals("\\\\\\\"quo\\\\\\\\ted\\\\\\\"", new String(buffer, 3, len));
+    }
+
+    @Test
+    void testJdkSerialize() throws IOException {
+        final byte[] bytes = jdkSerialize(new SerializedString(QUOTED));
+        SerializedString sstr = jdkDeserialize(bytes);
+        assertEquals(QUOTED, sstr.getValue());
+        final byte[] buffer = new byte[100];
+        final int len = sstr.appendQuotedUTF8(buffer, 3);
+        assertEquals("\\\\\\\"quo\\\\\\\\ted\\\\\\\"", new String(buffer, 3, len));
+    }
 }