diff --git a/contracts/DODOVendorMachine/impl/DVMStorage.sol b/contracts/DODOVendorMachine/impl/DVMStorage.sol
index dd5e988..ea67c83 100644
--- a/contracts/DODOVendorMachine/impl/DVMStorage.sol
+++ b/contracts/DODOVendorMachine/impl/DVMStorage.sol
@@ -16,7 +16,7 @@ import {DecimalMath} from "../../lib/DecimalMath.sol";
 import {IPermissionManager} from "../../lib/PermissionManager.sol";
 import {IGasPriceSource} from "../../lib/GasPriceSource.sol";
 import {IFeeRateModel} from "../../intf/IFeeRateModel.sol";
-import {DVMVault} from "./DVMVault.sol";
+import {IDVMVault} from "../intf/IDVMVault.sol";
 
 contract DVMStorage is InitializableOwnable, ReentrancyGuard {
     using SafeMath for uint256;
@@ -46,7 +46,7 @@ contract DVMStorage is InitializableOwnable, ReentrancyGuard {
     uint256 public _K_;
     uint256 public _I_;
 
-    DVMVault public _VAULT_;
+    IDVMVault public _VAULT_;
 
     // ============ Modifiers ============
 
diff --git a/contracts/DODOVendorMachine/intf/IDVMVault.sol b/contracts/DODOVendorMachine/intf/IDVMVault.sol
index eba49e2..de8a251 100644
--- a/contracts/DODOVendorMachine/intf/IDVMVault.sol
+++ b/contracts/DODOVendorMachine/intf/IDVMVault.sol
@@ -14,4 +14,58 @@ interface IDVMVault {
         address _baseToken,
         address _quoteToken
     ) external;
+
+    function _BASE_TOKEN_() external returns (address);
+
+    function _QUOTE_TOKEN_() external returns (address);
+
+    function _BASE_RESERVE_() external returns (address);
+
+    function _QUOTE_RESERVE_() external returns (address);
+
+    function symbol() external returns (string memory);
+
+    function decimals() external returns (uint256);
+
+    function name() external returns (string memory);
+
+    function totalSupply() external returns (uint256);
+
+    function getVaultBalance() external view returns (uint256 baseBalance, uint256 quoteBalance);
+
+    function getVaultReserve() external view returns (uint256 baseReserve, uint256 quoteReserve);
+
+    function getBaseBalance() external view returns (uint256 baseBalance);
+
+    function getQuoteBalance() external view returns (uint256 quoteBalance);
+
+    function getBaseInput() external view returns (uint256 input);
+
+    function getQuoteInput() external view returns (uint256 input);
+
+    function sync() external;
+
+    function transferBaseOut(address to, uint256 amount) external;
+
+    function transferQuoteOut(address to, uint256 amount) external;
+
+    function transfer(address to, uint256 amount) external returns (bool);
+
+    function balanceOf(address owner) external view returns (uint256 balance);
+
+    function shareRatioOf(address owner) external view returns (uint256 shareRatio);
+
+    function transferFrom(
+        address from,
+        address to,
+        uint256 amount
+    ) external returns (bool);
+
+    function approve(address spender, uint256 amount) external returns (bool);
+
+    function allowance(address owner, address spender) external view returns (uint256);
+
+    function mint(address user, uint256 value) external;
+
+    function burn(address user, uint256 value) external;
 }
diff --git a/test/DVM/trader.test.ts b/test/DVM/trader.test.ts
index 1b1b5f3..25bfecc 100644
--- a/test/DVM/trader.test.ts
+++ b/test/DVM/trader.test.ts
@@ -51,9 +51,6 @@ describe("Trader", () => {
   });
 
   describe("trade", () => {
-    // it.only("gas cost", async () => {
-    //   await logGas(ctx.DVM.methods.calculateBase0(decimalStr("200"), decimalStr("1")), ctx.sendParam(trader), "calculate base0")
-    // })
     it("buy & sell", async () => {
 
       console.log("BASE0 before buy", await ctx.DVM.methods.getBase0().call())
@@ -119,6 +116,37 @@ describe("Trader", () => {
         await ctx.QUOTE.methods.balanceOf(ctx.Maintainer).call(),
         "103733009669408099"
       );
+
+      // buy when quoet is not 0
+      await logGas(ctx.Route.methods.sellQuoteOnDVM(ctx.DVM.options.address, trader, decimalStr("200"), decimalStr("1")), ctx.sendParam(trader), "buy base token")
+      console.log("BASE0 after second buy", await ctx.DVM.methods.getBase0().call())
+      // trader balances
+      console.log(
+        await ctx.BASE.methods.balanceOf(trader).call(),
+        "12837528824326616018"
+      );
+      console.log(
+        await ctx.QUOTE.methods.balanceOf(trader).call(),
+        "703421810640399874603"
+      );
+      // vault balances
+      console.log(
+        await ctx.BASE.methods.balanceOf(ctx.Vault.options.address).call(),
+        "7158622099620899913"
+      );
+      console.log(
+        await ctx.QUOTE.methods.balanceOf(ctx.Vault.options.address).call(),
+        "296474456349930717298"
+      );
+      // maintainer balances
+      console.log(
+        await ctx.BASE.methods.balanceOf(ctx.Maintainer).call(),
+        "3849076052484069"
+      );
+      console.log(
+        await ctx.QUOTE.methods.balanceOf(ctx.Maintainer).call(),
+        "103733009669408099"
+      );
     });
   });
 });