diff --git a/liquidjava-verifier/pom.xml b/liquidjava-verifier/pom.xml
index 5b42f4cb..c3ad4899 100644
--- a/liquidjava-verifier/pom.xml
+++ b/liquidjava-verifier/pom.xml
@@ -1,6 +1,5 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 
 	<parent>
@@ -10,7 +9,7 @@
 	</parent>
 
 	<groupId>liquidjava-verifier
-		</groupId>
+	</groupId>
 	<artifactId>liquidjava-verifier</artifactId>
 	<version>5.2-SNAPSHOT</version>
 	<name>liquidjava-verifier</name>
@@ -95,6 +94,45 @@
 					</execution>
 				</executions>
 			</plugin>
+			<plugin>
+				<groupId>org.jacoco</groupId>
+				<artifactId>jacoco-maven-plugin</artifactId>
+				<version>0.8.14</version>
+				<executions>
+					<execution>
+						<id>default-prepare-agent</id>
+						<goals>
+							<goal>prepare-agent</goal>
+						</goals>
+					</execution>
+					<execution>
+						<id>default-report</id>
+						<goals>
+							<goal>report</goal>
+						</goals>
+					</execution>
+					<execution>
+						<id>default-check</id>
+						<goals>
+							<goal>check</goal>
+						</goals>
+						<configuration>
+							<rules>
+								<rule>
+									<element>BUNDLE</element>
+									<limits>
+										<limit>
+											<counter>COMPLEXITY</counter>
+											<value>COVEREDRATIO</value>
+											<minimum>0.60</minimum>
+										</limit>
+									</limits>
+								</rule>
+							</rules>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
 		</plugins>
 	</build>
 
diff --git a/liquidjava-verifier/src/test/java/liquidjava/ast/opt/TestOptimization.java b/liquidjava-verifier/src/test/java/liquidjava/ast/opt/TestOptimization.java
new file mode 100644
index 00000000..4144d9ab
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/ast/opt/TestOptimization.java
@@ -0,0 +1,33 @@
+package liquidjava.ast.opt;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.Test;
+
+import liquidjava.rj_language.ast.BinaryExpression;
+import liquidjava.rj_language.ast.LiteralBoolean;
+import liquidjava.rj_language.ast.LiteralInt;
+import liquidjava.rj_language.opt.ConstantFolding;
+import liquidjava.rj_language.opt.derivation_node.ValDerivationNode;
+
+public class TestOptimization {
+    @Test
+    public void testBinaryFold() {
+        BinaryExpression b = new BinaryExpression(new LiteralInt(1), "+", new LiteralInt(2));
+
+        ValDerivationNode r = ConstantFolding.fold(new ValDerivationNode(b, null));
+        assertEquals(r.getValue(), new LiteralInt(3));
+    }
+
+    @Test
+    public void testBinaryFoldBool() {
+        // Given: true != false
+        // Expected: true
+        BinaryExpression b = new BinaryExpression(new LiteralBoolean(true), "!=", new LiteralBoolean(false));
+
+        ValDerivationNode r = ConstantFolding.fold(new ValDerivationNode(b, null));
+
+        // Then:
+        assertEquals(r.getValue(), new LiteralBoolean(true), "Expect result to be true");
+    }
+}
diff --git a/liquidjava-verifier/src/test/java/liquidjava/rj_language/TestLiteralString.java b/liquidjava-verifier/src/test/java/liquidjava/rj_language/TestLiteralString.java
new file mode 100644
index 00000000..997de2c7
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/rj_language/TestLiteralString.java
@@ -0,0 +1,50 @@
+
+package liquidjava.rj_language;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.Assert.assertNotEquals;
+
+import org.junit.Test;
+import liquidjava.rj_language.ast.LiteralString;
+
+public class TestLiteralString {
+
+    @Test
+    public void testLiteralString() {
+        LiteralString s1 = new LiteralString("hello");
+        LiteralString s2 = new LiteralString("world");
+        assertNotEquals(s1.hashCode(), s2.hashCode());
+    }
+
+    @Test
+    public void testLiteralStringEqualsClass() {
+        // Given: s1.getClass() == LiteralString && s2.getClass() == String
+        // Expected: False (LiteralString != String)
+
+        LiteralString s1 = new LiteralString("hello");
+        String s2 = "hello";
+
+        // when
+        boolean result = s1.equals(s2);
+
+        // Then:
+        assertFalse(result, "Expected result to be False");
+    }
+
+    @Test
+    public void testLiteralStringEqualsNull() {
+        // Given: s1 == null && s2 == null
+        // Expected: True (null == null)
+
+        LiteralString s1 = new LiteralString(null);
+        LiteralString s2 = new LiteralString(null);
+
+        // When
+        boolean result = s1.equals(s2);
+
+        // Then
+        assertTrue(result, "Expected result to be True");
+    }
+
+}