Unknown block error for RPC (#3965)

ethcore/src/client/client.rs

@@ -619,7 +619,8 @@ impl Client {
 	/// Attempt to get a copy of a specific block's final state.
 	///
 	/// This will not fail if given BlockId::Latest.
-	/// Otherwise, this can fail (but may not) if the DB prunes state.
+	/// Otherwise, this can fail (but may not) if the DB prunes state or the block
+	/// is unknown.
 	pub fn state_at(&self, id: BlockId) -> Option<State> {
 		// fast path for latest state.
 		match id.clone() {

ethcore/src/client/test_client.rs

@@ -523,7 +523,8 @@ impl BlockChainClient for TestBlockChainClient {
 		match id {
 			BlockId::Number(number) if (number as usize) < self.blocks.read().len() => BlockStatus::InChain,
 			BlockId::Hash(ref hash) if self.blocks.read().get(hash).is_some() => BlockStatus::InChain,
-			_ => BlockStatus::Unknown
+			BlockId::Latest | BlockId::Pending | BlockId::Earliest => BlockStatus::InChain,
+			_ => BlockStatus::Unknown,
 		}
 	}
 

ethcore/src/client/traits.rs

@@ -277,7 +277,7 @@ pub trait BlockChainClient : Sync + Send {
 	/// Get the address of the registry itself.
 	fn registrar_address(&self) -> Option<Address>;
 
-	/// Get the address of a particular blockchain service, if available. 
+	/// Get the address of a particular blockchain service, if available.
 	fn registry_address(&self, name: String) -> Option<Address>;
 }