added missing eth_getBalance rpc method and tests for it

ethcore/src/client/client.rs

@@ -449,6 +449,10 @@ impl<V> BlockChainClient for Client<V> where V: Verifier {
 		self.state().code(address)
 	}
 
+	fn balance(&self, address: &Address) -> U256 {
+		self.state().balance(address)
+	}
+
 	fn transaction(&self, id: TransactionId) -> Option<LocalizedTransaction> {
 		match id {
 			TransactionId::Hash(ref hash) => self.chain.transaction_address(hash),

ethcore/src/client/mod.rs

@@ -66,6 +66,9 @@ pub trait BlockChainClient : Sync + Send {
 	/// Get address code.
 	fn code(&self, address: &Address) -> Option<Bytes>;
 
+	/// Get address balance.
+	fn balance(&self, address: &Address) -> U256;
+
 	/// Get transaction with given hash.
 	fn transaction(&self, id: TransactionId) -> Option<LocalizedTransaction>;
 

ethcore/src/client/test_client.rs

@@ -40,6 +40,8 @@ pub struct TestBlockChainClient {
 	pub last_hash: RwLock<H256>,
 	/// Difficulty.
 	pub difficulty: RwLock<U256>,
+	/// Balances.
+	pub balances: RwLock<HashMap<Address, U256>>,
 }
 
 #[derive(Clone)]
@@ -65,12 +67,17 @@ impl TestBlockChainClient {
 			genesis_hash: H256::new(),
 			last_hash: RwLock::new(H256::new()),
 			difficulty: RwLock::new(From::from(0)),
+			balances: RwLock::new(HashMap::new()),
 		};
 		client.add_blocks(1, EachBlockWith::Nothing); // add genesis block
 		client.genesis_hash = client.last_hash.read().unwrap().clone();
 		client
 	}
 
+	pub fn set_balance(&mut self, address: Address, balance: U256) {
+		self.balances.write().unwrap().insert(address, balance);
+	}
+
 	/// Add blocks to test client.
 	pub fn add_blocks(&mut self, count: usize, with: EachBlockWith) {
 		let len = self.numbers.read().unwrap().len();
@@ -165,6 +172,10 @@ impl BlockChainClient for TestBlockChainClient {
 		unimplemented!();
 	}
 
+	fn balance(&self, address: &Address) -> U256 {
+		self.balances.read().unwrap().get(address).cloned().unwrap_or_else(U256::zero)
+	}
+
 	fn transaction(&self, _id: TransactionId) -> Option<LocalizedTransaction> {
 		unimplemented!();
 	}