diff --git a/liquidjava b/liquidjava
old mode 100755
new mode 100644
diff --git a/liquidjava-verifier/pom.xml b/liquidjava-verifier/pom.xml
index 5b42f4cb..89d68300 100644
--- a/liquidjava-verifier/pom.xml
+++ b/liquidjava-verifier/pom.xml
@@ -77,7 +77,8 @@
 						</goals>
 						<configuration>
 							<transformers>
-								<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+								<transformer
+									implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
 									<mainClass>liquidjava.api.CommandLineLauncher</mainClass>
 								</transformer>
 							</transformers>
@@ -95,6 +96,45 @@
 					</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>0.5</minimum>
+										</limit>
+									</limits>
+								</rule>
+							</rules>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
 		</plugins>
 	</build>
 
@@ -206,4 +246,4 @@
 			</dependency>
 		</dependencies>
 	</dependencyManagement>
-</project>
+</project>
\ No newline at end of file
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..49de4f82
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/ast/opt/TestOptimization.java
@@ -0,0 +1,28 @@
+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.ast.UnaryExpression;
+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 testUnaryExpression() {
+        UnaryExpression u = new UnaryExpression("-", new LiteralInt(3));
+        ValDerivationNode vd = ConstantFolding.fold(new ValDerivationNode(u, null));
+        assertEquals(vd.getValue(), new LiteralInt(-3));
+    }
+}
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..b5cb6e57
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/rj_language/TestLiteralString.java
@@ -0,0 +1,15 @@
+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/TestPredicate.java b/liquidjava-verifier/src/test/java/liquidjava/rj_language/TestPredicate.java
new file mode 100644
index 00000000..aaef03c5
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/rj_language/TestPredicate.java
@@ -0,0 +1,13 @@
+package liquidjava.rj_language;
+
+import static org.junit.Assert.assertEquals;
+import org.junit.Test;
+
+public class TestPredicate {
+
+    @Test
+    public void testCreateInvocation() {
+        Predicate p = Predicate.createInvocation("test", Predicate.createVar("x"));
+        assertEquals("test(x)", p.getExpression().toString());
+    }
+}
diff --git a/liquidjava-verifier/src/test/java/liquidjava/rj_language/testLiteralBoolean.java b/liquidjava-verifier/src/test/java/liquidjava/rj_language/testLiteralBoolean.java
new file mode 100644
index 00000000..87fa0ace
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/rj_language/testLiteralBoolean.java
@@ -0,0 +1,16 @@
+package liquidjava.rj_language;
+
+import static org.junit.Assert.assertNotEquals;
+import org.junit.Test;
+
+import liquidjava.rj_language.ast.LiteralBoolean;
+
+public class testLiteralBoolean {
+
+    @Test
+    public void testLiteralBoolean() {
+        LiteralBoolean s1 = new LiteralBoolean(true);
+        LiteralBoolean s2 = new LiteralBoolean(false);
+        assertNotEquals(s1.hashCode(), s2.hashCode());
+    }
+}