fix test

contracts/SmartRoute/lib/UniversalERC20.sol

@@ -0,0 +1,59 @@
+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+
+import {SafeMath} from "../../lib/SafeMath.sol";
+import {IERC20} from "../../intf/IERC20.sol";
+import {SafeERC20} from "../../lib/SafeERC20.sol";
+
+library UniversalERC20 {
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
+
+    IERC20 private constant ETH_ADDRESS = IERC20(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
+
+    function isETH(IERC20 token) internal pure returns (bool) {
+        return token == ETH_ADDRESS;
+    }
+
+    function universalTransfer(
+        IERC20 token,
+        address payable to,
+        uint256 amount
+    ) internal {
+        if (amount > 0) {
+            if (isETH(token)) {
+                to.transfer(amount);
+            } else {
+                token.safeTransfer(to, amount);
+            }
+        }
+    }
+
+    function universalApproveMax(
+        IERC20 token,
+        address to,
+        uint256 amount
+    ) internal {
+        uint256 allowance = token.allowance(address(this), to);
+        if (allowance < amount) {
+            if (allowance > 0) {
+                token.safeApprove(to, 0);
+            }
+            token.safeApprove(to, uint256(-1));
+        }
+    }
+
+    function universalBalanceOf(IERC20 token, address who) internal view returns (uint256) {
+        if (isETH(token)) {
+            return who.balance;
+        } else {
+            return token.balanceOf(who);
+        }
+    }
+}