[storage] Add a unit test
diff --git a/services/storage/enclave/src/lib.rs b/services/storage/enclave/src/lib.rs
index 021f705..8d443f8 100644
--- a/services/storage/enclave/src/lib.rs
+++ b/services/storage/enclave/src/lib.rs
@@ -175,6 +175,7 @@
             service::tests::test_get_key,
             service::tests::test_put_key,
             service::tests::test_delete_key,
+            service::tests::test_empty_value,
             service::tests::test_enqueue,
             service::tests::test_dequeue,
             service::tests::test_get_keys_by_prefix,
diff --git a/services/storage/enclave/src/service.rs b/services/storage/enclave/src/service.rs
index 7326f01..af3feb1 100644
--- a/services/storage/enclave/src/service.rs
+++ b/services/storage/enclave/src/service.rs
@@ -322,6 +322,15 @@
         assert!(service.get(request).is_err());
     }
 
+    pub fn test_empty_value() {
+        let service = get_mock_service();
+        let request = PutRequest::new("test_empty_value", "");
+        assert!(service.put(request).is_ok());
+        let request = GetRequest::new("test_empty_value");
+        let response = service.get(request).unwrap();
+        assert_eq!(response.value, Vec::<u8>::new());
+    }
+
     pub fn test_enqueue() {
         let service = get_mock_service();
         let request = EnqueueRequest::new("test_enqueue_key", "1");