@0x/contracts-asset-proxy: Start work on UniswapBridge tests.

contracts/asset-proxy/contracts/src/bridges/UniswapBridge.sol

@@ -62,20 +62,18 @@ contract UniswaBridge is
             return BRIDGE_SUCCESS;
         }
 
-        uint256 fromTokenBalance = IERC20Token(fromToken).balanceOf(address(this));
-        uint256 toTokenBalance = IERC20Token(toToken).balanceOf(address(this));
-
         // Get the exchange for the token pair.
         IUniswapExchange exchange = _getUniswapExchangeForTokenPair(
             fromTokenAddress,
             toTokenAddress
         );
+        // Get our balance of `fromTokenAddress` token.
+        uint256 fromTokenBalance = IERC20Token(fromToken).balanceOf(address(this));
 
         // Convert from WETH to a token.
         if (fromTokenAddress == address(weth)) {
             // Unwrap the WETH.
-            IEtherToken weth = _getWethContract();
-            weth.withdraw(weth.balanceOf(this));
+            _getWethContract().withdraw(fromTokenBalance);
             // Buy as much of `toTokenAddress` token with ETH as possible and
             // transfer it to `to`.
             exchange.ethToTokenTransferInput.value(fromTokenBalance)(
@@ -99,10 +97,9 @@ contract UniswaBridge is
                 to
             );
             // Wrap the ETH.
-            IEtherToken weth = _getWethContract();
-            weth.deposit.value(ethBought)();
+            _getWethContract().deposit.value(ethBought)();
             // Transfer the WETH to `to`.
-            weth.transfer(to, ethBought);
+            IERC20Token(toTokenAddress).transfer(to, ethBought);
 
         // Convert from one token to another.
         } else {

contracts/asset-proxy/contracts/test/TestUniswapBridge.sol

@@ -0,0 +1,204 @@
+/*
+
+  Copyright 2019 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.5.9;
+pragma experimental ABIEncoderV2;
+
+import "@0x/contracts-erc20/contracts/src/interfaces/IERC20Token.sol";
+import "../src/bridges/Eth2DaiBridge.sol";
+import "../src/interfaces/IEth2Dai.sol";
+
+
+// solhint-disable no-simple-event-func-name
+/// @dev Interface that allows `TestToken` to call `raiseTransferEvent` on
+///      the `TestEth2DaiBridge` contract.
+interface ITestTokenCaller {
+
+    function raiseTransferEvent(
+        address from,
+        address to,
+        uint256 amount
+    )
+        external;
+
+    function raiseTransferEvent(
+        address from,
+        address to,
+        uint256 amount
+    )
+        external;
+}
+
+
+/// @dev A minimalist ERC20/WETH token.
+contract TestToken {
+
+    mapping (address => uint256) public balances;
+
+    /// @dev Just calls `raiseTransferEvent()` on the caller.
+    function transfer(address to, uint256 amount)
+        external
+        returns (bool)
+    {
+        IRaiseTransferEvent(msg.sender).raiseTransferEvent(msg.sender, to, amount);
+        return true;
+    }
+
+    /// @dev Set the balance for `owner`.
+    function setBalance(address owner, uint256 balance)
+        external
+    {
+        balances[owner] = balance;
+    }
+
+    /// @dev Just calls `raiseApproveEvent()` on the caller.
+    function approve(address spender, uint256 allowance)
+        external
+        returns (bool)
+    {
+        allowances[msg.sender][spender] = allowance;
+        return true;
+    }
+
+    /// @dev Retrieve the balance for `owner`.
+    function balanceOf(address owner)
+        external
+        view
+        returns (uint256)
+    {
+        return balances[owner];
+    }
+}
+
+
+/// @dev Eth2DaiBridge overridden to mock tokens and
+///      implement IEth2Dai.
+contract TestEth2DaiBridge is
+    IEth2Dai,
+    Eth2DaiBridge
+{
+    event SellAllAmount(
+        address sellToken,
+        uint256 sellTokenAmount,
+        address buyToken,
+        uint256 minimumFillAmount
+    );
+
+    event TokenTransfer(
+        address token,
+        address from,
+        address to,
+        uint256 amount
+    );
+
+    TestToken public wethToken = new TestToken();
+    TestToken public daiToken = new TestToken();
+    string private _nextRevertReason;
+    uint256 private _nextFillAmount;
+
+    /// @dev Set token balances for this contract.
+    function setTokenBalances(uint256 wethBalance, uint256 daiBalance)
+        external
+    {
+        wethToken.setBalance(address(this), wethBalance);
+        daiToken.setBalance(address(this), daiBalance);
+    }
+
+    /// @dev Set the behavior for `IEth2Dai.sellAllAmount()`.
+    function setFillBehavior(string calldata revertReason, uint256 fillAmount)
+        external
+    {
+        _nextRevertReason = revertReason;
+        _nextFillAmount = fillAmount;
+    }
+
+    /// @dev Implementation of `IEth2Dai.sellAllAmount()`
+    function sellAllAmount(
+        address sellTokenAddress,
+        uint256 sellTokenAmount,
+        address buyTokenAddress,
+        uint256 minimumFillAmount
+    )
+        external
+        returns (uint256 fillAmount)
+    {
+        emit SellAllAmount(
+            sellTokenAddress,
+            sellTokenAmount,
+            buyTokenAddress,
+            minimumFillAmount
+        );
+        if (bytes(_nextRevertReason).length != 0) {
+            revert(_nextRevertReason);
+        }
+        return _nextFillAmount;
+    }
+
+    function raiseTransferEvent(
+        address from,
+        address to,
+        uint256 amount
+    )
+        external
+    {
+        emit TokenTransfer(
+            msg.sender,
+            from,
+            to,
+            amount
+        );
+    }
+
+    /// @dev Retrieves the allowances of the test tokens.
+    function getEth2DaiTokenAllowances()
+        external
+        view
+        returns (uint256 wethAllowance, uint256 daiAllowance)
+    {
+        wethAllowance = wethToken.allowances(address(this), address(this));
+        daiAllowance = daiToken.allowances(address(this), address(this));
+        return (wethAllowance, daiAllowance);
+    }
+
+    // @dev Use `wethToken`.
+    function _getWethContract()
+        internal
+        view
+        returns (IERC20Token)
+    {
+        return IERC20Token(address(wethToken));
+    }
+
+    // @dev Use `daiToken`.
+    function _getDaiContract()
+        internal
+        view
+        returns (IERC20Token)
+    {
+        return IERC20Token(address(daiToken));
+    }
+
+    // @dev This contract will double as the Eth2Dai contract.
+    function _getEth2DaiContract()
+        internal
+        view
+        returns (IEth2Dai)
+    {
+        return IEth2Dai(address(this));
+    }
+}