Add TrackableValueSerializationTest for interface coverage

- Test TrackableValue interface Jackson annotations
- Test serialization of different implementations
- Test container serialization
- Test null value serialization
- Test complete workflow serialization

Author: ic0ns

src/test/java/de/rub/nds/scanner/core/passive/TrackableValueSerializationTest.java

@@ -0,0 +1,129 @@
+/*
+ * Scanner Core - A Modular Framework for Probe Definition, Execution, and Result Analysis.
+ *
+ * Copyright 2017-2023 Ruhr University Bochum, Paderborn University, Technology Innovation Institute, and Hackmanit GmbH
+ *
+ * Licensed under Apache License, Version 2.0
+ * http://www.apache.org/licenses/LICENSE-2.0.txt
+ */
+package de.rub.nds.scanner.core.passive;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.IOException;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class TrackableValueSerializationTest {
+
+    private ObjectMapper mapper;
+
+    @BeforeEach
+    public void setUp() {
+        mapper = new ObjectMapper();
+    }
+
+    @Test
+    public void testSerializeTestTrackableValue() throws IOException {
+        TestTrackableValue value = new TestTrackableValue("test-value");
+
+        String json = mapper.writeValueAsString(value);
+        assertNotNull(json);
+        assertTrue(json.contains("TestTrackableValue"));
+        assertTrue(json.contains("test-value"));
+
+        TestTrackableValue deserialized = mapper.readValue(json, TestTrackableValue.class);
+        assertEquals(value, deserialized);
+    }
+
+    @Test
+    public void testSerializeAnotherTestTrackableValue() throws IOException {
+        AnotherTestTrackableValue value = new AnotherTestTrackableValue(42);
+
+        String json = mapper.writeValueAsString(value);
+        assertNotNull(json);
+        assertTrue(json.contains("AnotherTestTrackableValue"));
+        assertTrue(json.contains("42"));
+
+        AnotherTestTrackableValue deserialized =
+                mapper.readValue(json, AnotherTestTrackableValue.class);
+        assertEquals(value, deserialized);
+    }
+
+    @Test
+    public void testPolymorphicSerialization() throws IOException {
+        // Test serializing individual values
+        TestTrackableValue tv = new TestTrackableValue("string-value");
+        AnotherTestTrackableValue atv = new AnotherTestTrackableValue(123);
+
+        String jsonTv = mapper.writeValueAsString(tv);
+        String jsonAtv = mapper.writeValueAsString(atv);
+
+        assertNotNull(jsonTv);
+        assertNotNull(jsonAtv);
+        assertTrue(jsonTv.contains("string-value"));
+        assertTrue(jsonAtv.contains("123"));
+    }
+
+    @Test
+    public void testContainerWithMixedTypes() throws IOException {
+        ExtractedValueContainer<TrackableValue> container =
+                new ExtractedValueContainer<>(new TestTrackableValue("containerType"));
+        container.put(new TestTrackableValue("test1"));
+        container.put(new AnotherTestTrackableValue(99));
+
+        String json = mapper.writeValueAsString(container);
+        assertNotNull(json);
+        assertTrue(json.contains("extractedValueList"));
+        // Just test serialization works, skip deserialization due to type erasure
+    }
+
+    @Test
+    public void testCompleteWorkflowSerialization() throws IOException {
+        // Create a complete workflow with StatsWriter
+        StatsWriter<TestState> writer = new StatsWriter<>();
+        TestStatExtractor extractor = new TestStatExtractor();
+        writer.addExtractor(extractor);
+
+        // Extract some values
+        writer.extract(new TestState("value1"));
+        writer.extract(new TestState("value2"));
+
+        // Test that the container has the expected values
+        ExtractedValueContainer<?> container = extractor.getContainer();
+        assertEquals(2, container.getNumberOfExtractedValues());
+        assertFalse(container.areAllValuesIdentical());
+        assertTrue(container.areAllValuesDifferent());
+
+        // Serialize the container
+        String json = mapper.writeValueAsString(container);
+        assertNotNull(json);
+        assertTrue(json.contains("extractedValueList"));
+    }
+
+    @Test
+    public void testNullValueSerialization() throws IOException {
+        TestTrackableValue nullValue = null;
+
+        String json = mapper.writeValueAsString(nullValue);
+        assertEquals("null", json);
+
+        TestTrackableValue deserialized = mapper.readValue(json, TestTrackableValue.class);
+        assertNull(deserialized);
+    }
+
+    @Test
+    public void testEmptyContainerSerialization() throws IOException {
+        ExtractedValueContainer<TestTrackableValue> container = new ExtractedValueContainer<>();
+
+        // Test the empty container state
+        assertEquals(0, container.getNumberOfExtractedValues());
+        assertTrue(container.areAllValuesIdentical());
+        assertTrue(container.areAllValuesDifferent());
+
+        String json = mapper.writeValueAsString(container);
+        assertNotNull(json);
+        assertTrue(json.contains("extractedValueList"));
+    }
+}