fix(vault): revert deposit if adapter credits zero shares (554)

packages/contracts/vault/src/lib.rs

@@ -141,6 +141,7 @@ pub enum ContractError {
     /// malformed protocol response. Depositing would dilute all existing
     /// holders.
     AdapterReportedNoAssets = 17,
+    AdapterCreditedNothing = 15,
 }
 
 // ---------------------------------------------------------------------------
@@ -250,6 +251,9 @@ impl MeridianVault {
 
         // Adapter deploys USDC to the underlying protocol and returns its own shares.
         let adapter_shares = AdapterClient::new(&env, &adapter_addr).deposit(&amount);
+        if adapter_shares <= 0 {
+            return Err(ContractError::AdapterCreditedNothing);
+        }
 
         // Mint mUSDC shares to caller.
         token::StellarAssetClient::new(&env, &musdc).mint(&caller, &shares_to_mint);
@@ -1731,6 +1735,28 @@ mod tests {
         assert_eq!(result, Err(Ok(ContractError::SameAdapter)));
     }
 
+    #[test]
+    fn deposit_fails_when_adapter_returns_zero_shares() {
+      use zero_share_mock::{ZeroShareMockAdapter, ZeroShareMockAdapterClient};
+
+      let (env, admin, user, usdc, _adapter, _vault) = setup();
+      let amount = 100_000000_i128;
+
+// Register and initialize zero share adapter
+let zero_share_adapter_id = env.register(ZeroShareMockAdapter, ());
+ZeroShareMockAdapterClient::new(&env, &zero_share_adapter_id).initialize(&usdc);
+
+// Deploy a vault configured with the zero-share adapter
+let musdc_id = env.register_stellar_asset_contract_v2(admin.clone()).address();
+let vault_id = env.register(MeridianVault, ());
+let vault = MeridianVaultClient::new(&env, &vault_id);
+vault.initialize(&admin, &usdc, &musdc_id, &zero_share_adapter_id);
+
+// Attempt deposit and assert it returns AdapterCreditedNothing (error code 15)
+let result = vault.try_deposit(&user, &amount);
+assert_eq!(result, Err(Ok(ContractError::AdapterCreditedNothing)));
+}
+
     #[test]
     fn migrate_adapter_rejects_value_drift_beyond_slippage() {
         use lossy_mock::{LossyMockAdapter, LossyMockAdapterClient};