diff --git a/services/payments/src/test/java/com/klaro/bais/payments/PaymentReferenceServiceTest.java b/services/payments/src/test/java/com/klaro/bais/payments/PaymentReferenceServiceTest.java
new file mode 100644
index 0000000..f198d3a
--- /dev/null
+++ b/services/payments/src/test/java/com/klaro/bais/payments/PaymentReferenceServiceTest.java
@@ -0,0 +1,22 @@
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class PaymentReferenceServiceTest {
+
+    PaymentReferenceService service = new PaymentReferenceService();
+
+    @Test
+    void testNormalize_null() {
+        assertEquals("", service.normalize(null));
+    }
+
+    @Test
+    void testNormalize_empty() {
+        assertEquals("", service.normalize(""));
+    }
+
+    @Test
+    void testNormalize_normalString() {
+        assertEquals("test", service.normalize("  test  "));
+    }
+}