chore: add negative uint128 sub unwrap default test

Author: ducphamle2

contracts/cw-ics20-latest/src/ibc_tests.rs

@@ -46,6 +46,16 @@ mod test {
         assert_eq!(r#"{"error":"bad coin"}"#, fail_json.as_str());
     }
 
+    #[test]
+    fn test_sub_negative() {
+        assert_eq!(
+            Uint128::from(10u128)
+                .checked_sub(Uint128::from(11u128))
+                .unwrap_or_default(),
+            Uint128::from(0u128)
+        )
+    }
+
     #[test]
     fn check_packet_json() {
         let packet = Ics20Packet::new(