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..d99b0e7a
--- /dev/null
+++ b/liquidjava-verifier/src/test/java/liquidjava/rj_language/opt/TestOptimization.java
@@ -0,0 +1,18 @@
+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(r.getValue(), new LiteralInt(3));
+    }
+}
\ No newline at end of file