Add more tests for ERC721

contracts/mocks/ERC721ReceiverMock.sol

@@ -0,0 +1,21 @@
+pragma solidity ^0.4.18;
+
+import "../token/ERC721/ERC721Receiver.sol";
+
+contract ERC721ReceiverMock is ERC721Receiver {
+  bytes4 retval;
+  bool reverts;
+
+  event Received(address _address, uint256 _tokenId, bytes _data, uint256 _gas);
+
+  function ERC721ReceiverMock(bytes4 _retval, bool _reverts) public {
+    retval = _retval;
+    reverts = _reverts;
+  }
+
+  function onERC721Received(address _address, uint256 _tokenId, bytes _data) public returns(bytes4) {
+    require(!reverts);
+    Received(_address, _tokenId, _data, msg.gas);
+    return retval;
+  }
+}

contracts/mocks/ERC721TokenMock.sol

@@ -20,13 +20,20 @@ contract ERC721TokenMock is ERC721Token, ERC721BasicTokenMock {
   function tokenURI(uint256 _tokenId) public view returns (string) {
     require(exists(_tokenId));
 
-    bytes memory uri = new bytes(78);
+    bytes memory uri = new bytes(78 + 7);
 
     uint256 i;
     uint256 value = _tokenId;
 
+    uri[0] = "m";
+    uri[1] = "o";
+    uri[2] = "c";
+    uri[3] = "k";
+    uri[4] = ":";
+    uri[5] = "/";
+    uri[6] = "/";
     for (i = 0; i < 78; i++) {
-      uri[7 + 78 - i] = byte(value % 10 + 48);
+      uri[6 + 78 - i] = byte(value % 10 + 48);
       value = value / 10;
     }
 

contracts/token/ERC721/ERC721BasicToken.sol

@@ -177,9 +177,7 @@ contract ERC721BasicToken is ERC721Basic {
   * @param _tokenId uint256 ID of the token being burned by the msg.sender
   */
   function doBurn(uint256 _tokenId) onlyOwnerOf(_tokenId) internal {
-    if (getApproved(_tokenId) != 0) {
-      clearApproval(msg.sender, _tokenId);
-    }
+    clearApproval(msg.sender, _tokenId);
     removeToken(msg.sender, _tokenId);
     totalTokens = totalTokens.sub(1);
     Transfer(msg.sender, 0x0, _tokenId);
@@ -214,8 +212,10 @@ contract ERC721BasicToken is ERC721Basic {
   */
   function clearApproval(address _owner, uint256 _tokenId) internal {
     require(ownerOf(_tokenId) == _owner);
-    tokenApprovals[_tokenId] = 0;
-    Approval(_owner, 0, _tokenId);
+    if (tokenApprovals[_tokenId] != 0) {
+      tokenApprovals[_tokenId] = 0;
+      Approval(_owner, 0, _tokenId);
+    }
   }
 
   /**

test/helpers/sendTransaction.js

@@ -0,0 +1,17 @@
+const _ = require('lodash');
+const ethjsABI = require('ethjs-abi');
+
+export function findMethod (abi, name, args) {
+  for (var i = 0; i < abi.length; i++) {
+    const methodArgs = _.map(abi[i].inputs, 'type').join(',');
+    if ((abi[i].name === name) && (methodArgs === args)) {
+      return abi[i];
+    }
+  }
+}
+
+export default function sendTransaction (target, name, argsTypes, argsValues, opts) {
+  const abiMethod = findMethod(target.abi, name, argsTypes);
+  const encodedData = ethjsABI.encodeMethod(abiMethod, argsValues);
+  return target.sendTransaction(Object.assign({ data: encodedData }, opts));
+}