diff --git a/src/executive.rs b/src/executive.rs
index 4e829cdd5..0fdb46335 100644
--- a/src/executive.rs
+++ b/src/executive.rs
@@ -55,7 +55,6 @@ pub struct Executed {
 	pub cumulative_gas_used: U256,
 	/// Vector of logs generated by transaction.
 	pub logs: Vec<LogEntry>,
-
 	/// Execution ended running out of gas.
 	pub out_of_gas: bool,
 	/// Addresses of contracts created during execution of transaction.
@@ -102,8 +101,6 @@ impl<'a> Executive<'a> {
 
 	/// This funtion should be used to execute transaction.
 	pub fn transact(&mut self, t: &Transaction) -> Result<Executed, Error> {
-		// TODO: validate transaction signature ?/ sender
-
 		let sender = try!(t.sender());
 		let nonce = self.state.nonce(&sender);
 
@@ -244,9 +241,10 @@ impl<'a> Executive<'a> {
 				self.state.add_balance(&t.sender().unwrap(), &refund_value);
 				
 				// fees earned by author
-				let fees = (t.gas - refund) * t.gas_price;
+				let fees = t.gas - refund;
+				let fees_value = fees * t.gas_price;
 				let author = &self.info.author;
-				self.state.add_balance(author, &fees);
+				self.state.add_balance(author, &fees_value);
 
 				// perform suicides
 				for address in substate.suicides.iter() {
@@ -742,4 +740,76 @@ mod tests {
 		assert_eq!(state.storage_at(&address, &H256::from(&U256::zero())), H256::from(&U256::from(1)));
 		assert_eq!(state.storage_at(&address, &H256::from(&U256::one())), H256::from(&U256::from(1)));
 	}
+
+	#[test]
+	fn test_transact_simple() {
+		let mut t = Transaction::new(U256::zero(), U256::zero(), U256::from(100_000), Action::Create, U256::from(17), "3331600055".from_hex().unwrap());
+		t.r = U256::from_str("98ff921201554726367d2be8c804a7ff89ccf285ebc57dff8ae4c44b9c19ac4a").unwrap();
+		t.s = U256::from_str("8887321be575c8095f789dd4c743dfe42c1820f9231f98a962b210e3ac2452a3").unwrap();
+		t.v = 0x1c;
+		let sender = t.sender().unwrap();
+
+		let mut state = State::new_temp();
+		state.add_balance(&sender, &U256::from(17));	
+		let mut info = EnvInfo::new();
+		info.gas_limit = U256::from(100_000);
+		let engine = TestEngine::new(0);
+
+		let executed = {
+			let mut ex = Executive::new(&mut state, &info, &engine);
+			ex.transact(&t).unwrap()
+		};
+
+		assert_eq!(executed.gas, U256::from(100_000));
+		assert_eq!(executed.gas_used, U256::from(5025));
+		assert_eq!(executed.refunded, U256::from(94_975));
+		assert_eq!(executed.cumulative_gas_used, U256::from(5025));
+		assert_eq!(executed.logs.len(), 0);
+		assert_eq!(executed.out_of_gas, false);
+		assert_eq!(executed.contracts_created.len(), 0);
+	}
+
+	#[test]
+	fn test_transact_invalid_sender() {
+		let mut t = Transaction::new(U256::zero(), U256::zero(), U256::from(100_000), Action::Create, U256::from(17), "3331600055".from_hex().unwrap());
+		t.r = U256::from_str("98ff921201554726367d2be8c804a7ff89ccf285ebc57dff8ae4c44b9c19ac4a").unwrap();
+		t.s = U256::from_str("8887321be575c8095f789dd4c743dfe42c1820f9231f98a962b210e3ac2452a3").unwrap();
+		t.v = 0x1d;
+
+		let mut state = State::new_temp();
+		let info = EnvInfo::new();
+		let engine = TestEngine::new(0);
+
+		let res = {
+			let mut ex = Executive::new(&mut state, &info, &engine);
+			ex.transact(&t)
+		};
+		
+		match res {
+			Err(Error::Util(UtilError::Crypto(CryptoError::InvalidSignature))) => (),
+			_ => assert!(false, "expected signature error")
+		}
+	}
+
+	#[test]
+	fn test_transact_invalid_nonce() {
+		let mut t = Transaction::new(U256::one(), U256::zero(), U256::from(100_000), Action::Create, U256::from(17), "3331600055".from_hex().unwrap());
+		t.r = U256::from_str("98ff921201554726367d2be8c804a7ff89ccf285ebc57dff8ae4c44b9c19ac4a").unwrap();
+		t.s = U256::from_str("8887321be575c8095f789dd4c743dfe42c1820f9231f98a962b210e3ac2452a3").unwrap();
+		t.v = 0x1c;
+
+		let mut state = State::new_temp();
+		let info = EnvInfo::new();
+		let engine = TestEngine::new(0);
+
+		let res = {
+			let mut ex = Executive::new(&mut state, &info, &engine);
+			ex.transact(&t)
+		};
+		
+		match res {
+			Err(Error::Execution(ExecutionError::InvalidNonce { expected, is })) if expected == U256::zero() && is == U256::one() => (), 
+			_ => assert!(false, "expected signature error")
+		}
+	}
 }
diff --git a/src/transaction.rs b/src/transaction.rs
index 661c1355f..df7da7da2 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -27,6 +27,21 @@ pub struct Transaction {
 }
 
 impl Transaction {
+	pub fn new(nonce: U256, gas_price: U256, gas: U256, action: Action, value: U256, data: Bytes) -> Transaction {
+		Transaction {
+			nonce: nonce,
+			gas_price: gas_price,
+			gas: gas,
+			action: action,
+			value: value,
+			data: data,
+			v: 0,
+			r: U256::zero(),
+			s: U256::zero(),
+			hash: RefCell::new(None)
+		}
+	}
+
 	/// Append object into RLP stream, optionally with or without the signature.
 	pub fn rlp_append_opt(&self, s: &mut RlpStream, with_seal: Seal) {
 		s.append_list(6 + match with_seal { Seal::With => 3, _ => 0 });