add estimateGas to contract methods and fixed sendTransaction return …

…value

lib/web3/function.js

@@ -122,13 +122,30 @@ SolidityFunction.prototype.sendTransaction = function () {
     var payload = this.toPayload(args);
 
     if (!callback) {
-        web3.eth.sendTransaction(payload);
-        return;
+        return web3.eth.sendTransaction(payload);;
     }
 
     web3.eth.sendTransaction(payload, callback);
 };
 
+/**
+ * Should be used to estimateGas of solidity function
+ *
+ * @method estimateGas
+ * @param {Object} options
+ */
+SolidityFunction.prototype.estimateGas = function () {
+    var args = Array.prototype.slice.call(arguments);
+    var callback = this.extractCallback(args);
+    var payload = this.toPayload(args);
+
+    if (!callback) {
+        return web3.eth.estimateGas(payload);
+    }
+
+    web3.eth.estimateGas(payload, callback);
+};
+
 /**
  * Should be used to get function display name
  *
@@ -196,6 +213,7 @@ SolidityFunction.prototype.attachToContract = function (contract) {
     execute.request = this.request.bind(this);
     execute.call = this.call.bind(this);
     execute.sendTransaction = this.sendTransaction.bind(this);
+    execute.estimateGas = this.estimateGas.bind(this);
     var displayName = this.displayName();
     if (!contract[displayName]) {
         contract[displayName] = execute;

test/contract.js

@@ -296,6 +296,31 @@ describe('web3.eth.contract', function () {
             });
         });
 
+        it('should explicitly estimateGas with optional params', function () {
+            var provider = new FakeHttpProvider();
+            web3.setProvider(provider);
+            web3.reset();
+            var signature = 'send(address,uint256)';
+            var address = '0x1234567890123456789012345678901234567890';
+            provider.injectValidation(function (payload) {
+                assert.equal(payload.method, 'eth_estimateGas');
+                assert.deepEqual(payload.params, [{
+                    data: '0x' + sha3(signature).slice(0, 8) + 
+                        '0000000000000000000000001234567890123456789012345678901234567890' + 
+                        '0000000000000000000000000000000000000000000000000000000000000011' ,
+                    to: address,
+                    from: address,
+                    gas: '0xc350',
+                    gasPrice: '0xbb8',
+                    value: '0x2710'
+                }]);
+            });
+
+            var contract = web3.eth.contract(desc).at(address);
+
+            contract.send.estimateGas(address, 17, {from: address, gas: 50000, gasPrice: 3000, value: 10000});
+        });
+
         it('should call testArr method and properly parse result', function () {
             var provider = new FakeHttpProvider2();
             web3.setProvider(provider);