diff --git a/liquidjava-verifier/pom.xml b/liquidjava-verifier/pom.xml
index 5b42f4cb..0f730c7e 100644
--- a/liquidjava-verifier/pom.xml
+++ b/liquidjava-verifier/pom.xml
@@ -95,6 +95,46 @@
 					</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/rj_language/opt/TestLiteralString.java b/liquidjava-verifier/src/test/java/liquidjava/rj_language/opt/TestLiteralString.java
new file mode 100644
index 00000000..7e82772f
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/rj_language/opt/TestLiteralString.java
@@ -0,0 +1,14 @@
+package liquidjava.rj_language;
+
+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());
+    }
+}
diff --git a/liquidjava-verifier/src/test/java/liquidjava/rj_language/opt/TestOptimization.java b/liquidjava-verifier/src/test/java/liquidjava/rj_language/opt/TestOptimization.java
new file mode 100644
index 00000000..870883ff
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/rj_language/opt/TestOptimization.java
@@ -0,0 +1,18 @@
+package liquidjava.ast.opt;
+
+import static org.junit.Assert.assertEquals;
+import org.junit.Test;
+
+import liquidjava.rj_language.ast.BinaryExpression;
+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(new LiteralInt(3), r.getValue());
+    }
+}