diff --git a/sync/src/chain.rs b/sync/src/chain.rs
index 665508d92..40cbd496b 100644
--- a/sync/src/chain.rs
+++ b/sync/src/chain.rs
@@ -1013,3 +1013,7 @@ impl ChainSync {
 		}
 	}
 }
+
+#[cfg(test)]
+mod tests {
+}
\ No newline at end of file
diff --git a/sync/src/lib.rs b/sync/src/lib.rs
index f3b43396c..1523a8a9f 100644
--- a/sync/src/lib.rs
+++ b/sync/src/lib.rs
@@ -109,6 +109,4 @@ impl NetworkProtocolHandler<SyncMessage> for EthSync {
 		self.sync.write().unwrap().maintain_peers(&mut NetSyncIo::new(io, self.chain.deref()));
 		self.sync.write().unwrap().maintain_sync(&mut NetSyncIo::new(io, self.chain.deref()));
 	}
-}
-
-
+}
\ No newline at end of file
diff --git a/sync/src/tests/chain.rs b/sync/src/tests/chain.rs
new file mode 100644
index 000000000..083a9bd33
--- /dev/null
+++ b/sync/src/tests/chain.rs
@@ -0,0 +1,91 @@
+use util::*;
+use ethcore::client::{BlockChainClient};
+use io::SyncIo;
+use chain::{SyncState};
+use super::helpers::*;
+
+#[test]
+fn chain_two_peers() {
+	::env_logger::init().ok();
+	let mut net = TestNet::new(3);
+	net.peer_mut(1).chain.add_blocks(1000, false);
+	net.peer_mut(2).chain.add_blocks(1000, false);
+	net.sync();
+	assert!(net.peer(0).chain.block_at(1000).is_some());
+	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
+}
+
+#[test]
+fn chain_status_after_sync() {
+	::env_logger::init().ok();
+	let mut net = TestNet::new(3);
+	net.peer_mut(1).chain.add_blocks(1000, false);
+	net.peer_mut(2).chain.add_blocks(1000, false);
+	net.sync();
+	let status = net.peer(0).sync.status();
+	assert_eq!(status.state, SyncState::Idle);
+}
+
+#[test]
+fn chain_takes_few_steps() {
+	let mut net = TestNet::new(3);
+	net.peer_mut(1).chain.add_blocks(100, false);
+	net.peer_mut(2).chain.add_blocks(100, false);
+	let total_steps = net.sync();
+	assert!(total_steps < 7);
+}
+
+#[test]
+fn chain_empty_blocks() {
+	::env_logger::init().ok();
+	let mut net = TestNet::new(3);
+	for n in 0..200 {
+		net.peer_mut(1).chain.add_blocks(5, n % 2 == 0);
+		net.peer_mut(2).chain.add_blocks(5, n % 2 == 0);
+	}
+	net.sync();
+	assert!(net.peer(0).chain.block_at(1000).is_some());
+	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
+}
+
+#[test]
+fn chain_forked() {
+	::env_logger::init().ok();
+	let mut net = TestNet::new(3);
+	net.peer_mut(0).chain.add_blocks(300, false);
+	net.peer_mut(1).chain.add_blocks(300, false);
+	net.peer_mut(2).chain.add_blocks(300, false);
+	net.peer_mut(0).chain.add_blocks(100, true); //fork
+	net.peer_mut(1).chain.add_blocks(200, false);
+	net.peer_mut(2).chain.add_blocks(200, false);
+	net.peer_mut(1).chain.add_blocks(100, false); //fork between 1 and 2
+	net.peer_mut(2).chain.add_blocks(10, true);
+	// peer 1 has the best chain of 601 blocks
+	let peer1_chain = net.peer(1).chain.numbers.read().unwrap().clone();
+	net.sync();
+	assert_eq!(net.peer(0).chain.numbers.read().unwrap().deref(), &peer1_chain);
+	assert_eq!(net.peer(1).chain.numbers.read().unwrap().deref(), &peer1_chain);
+	assert_eq!(net.peer(2).chain.numbers.read().unwrap().deref(), &peer1_chain);
+}
+
+#[test]
+fn chain_restart() {
+	let mut net = TestNet::new(3);
+	net.peer_mut(1).chain.add_blocks(1000, false);
+	net.peer_mut(2).chain.add_blocks(1000, false);
+
+	net.sync_steps(8);
+
+	// make sure that sync has actually happened
+	assert!(net.peer(0).chain.chain_info().best_block_number > 100);
+	net.restart_peer(0);
+
+	let status = net.peer(0).sync.status();
+	assert_eq!(status.state, SyncState::NotSynced);
+}
+
+#[test]
+fn chain_status_empty() {
+	let net = TestNet::new(2);
+	assert_eq!(net.peer(0).sync.status().state, SyncState::NotSynced);
+}
\ No newline at end of file
diff --git a/sync/src/tests.rs b/sync/src/tests/helpers.rs
similarity index 71%
rename from sync/src/tests.rs
rename to sync/src/tests/helpers.rs
index 88f19a8b6..7fdd695fb 100644
--- a/sync/src/tests.rs
+++ b/sync/src/tests/helpers.rs
@@ -4,14 +4,14 @@ use ethcore::block_queue::BlockQueueInfo;
 use ethcore::header::{Header as BlockHeader, BlockNumber};
 use ethcore::error::*;
 use io::SyncIo;
-use chain::{ChainSync, SyncState};
+use chain::{ChainSync};
 
-struct TestBlockChainClient {
-	blocks: RwLock<HashMap<H256, Bytes>>,
- 	numbers: RwLock<HashMap<usize, H256>>,
-	genesis_hash: H256,
-	last_hash: RwLock<H256>,
-	difficulty: RwLock<U256>,
+pub struct TestBlockChainClient {
+	pub blocks: RwLock<HashMap<H256, Bytes>>,
+ 	pub numbers: RwLock<HashMap<usize, H256>>,
+	pub genesis_hash: H256,
+	pub last_hash: RwLock<H256>,
+	pub difficulty: RwLock<U256>,
 }
 
 impl TestBlockChainClient {
@@ -189,10 +189,10 @@ impl BlockChainClient for TestBlockChainClient {
 	}
 }
 
-struct TestIo<'p> {
-	chain: &'p mut TestBlockChainClient,
-	queue: &'p mut VecDeque<TestPacket>,
-	sender: Option<PeerId>,
+pub struct TestIo<'p> {
+	pub chain: &'p mut TestBlockChainClient,
+	pub queue: &'p mut VecDeque<TestPacket>,
+	pub sender: Option<PeerId>,
 }
 
 impl<'p> TestIo<'p> {
@@ -235,21 +235,21 @@ impl<'p> SyncIo for TestIo<'p> {
 	}
 }
 
-struct TestPacket {
-	data: Bytes,
-	packet_id: PacketId,
-	recipient: PeerId,
+pub struct TestPacket {
+	pub data: Bytes,
+	pub packet_id: PacketId,
+	pub recipient: PeerId,
 }
 
-struct TestPeer {
-	chain: TestBlockChainClient,
-	sync: ChainSync,
-	queue: VecDeque<TestPacket>,
+pub struct TestPeer {
+	pub chain: TestBlockChainClient,
+	pub sync: ChainSync,
+	pub queue: VecDeque<TestPacket>,
 }
 
-struct TestNet {
-	peers: Vec<TestPeer>,
-	started: bool,
+pub struct TestNet {
+	pub peers: Vec<TestPeer>,
+	pub started: bool,
 }
 
 impl TestNet {
@@ -329,89 +329,3 @@ impl TestNet {
 		self.peers.iter().all(|p| p.queue.is_empty())
 	}
 }
-
-#[test]
-fn chain_two_peers() {
-	::env_logger::init().ok();
-	let mut net = TestNet::new(3);
-	net.peer_mut(1).chain.add_blocks(1000, false);
-	net.peer_mut(2).chain.add_blocks(1000, false);
-	net.sync();
-	assert!(net.peer(0).chain.block_at(1000).is_some());
-	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
-}
-
-#[test]
-fn chain_status_after_sync() {
-	::env_logger::init().ok();
-	let mut net = TestNet::new(3);
-	net.peer_mut(1).chain.add_blocks(1000, false);
-	net.peer_mut(2).chain.add_blocks(1000, false);
-	net.sync();
-	let status = net.peer(0).sync.status();
-	assert_eq!(status.state, SyncState::Idle);
-}
-
-#[test]
-fn chain_takes_few_steps() {
-	let mut net = TestNet::new(3);
-	net.peer_mut(1).chain.add_blocks(100, false);
-	net.peer_mut(2).chain.add_blocks(100, false);
-	let total_steps = net.sync();
-	assert!(total_steps < 7);
-}
-
-#[test]
-fn chain_empty_blocks() {
-	::env_logger::init().ok();
-	let mut net = TestNet::new(3);
-	for n in 0..200 {
-		net.peer_mut(1).chain.add_blocks(5, n % 2 == 0);
-		net.peer_mut(2).chain.add_blocks(5, n % 2 == 0);
-	}
-	net.sync();
-	assert!(net.peer(0).chain.block_at(1000).is_some());
-	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
-}
-
-#[test]
-fn chain_forked() {
-	::env_logger::init().ok();
-	let mut net = TestNet::new(3);
-	net.peer_mut(0).chain.add_blocks(300, false);
-	net.peer_mut(1).chain.add_blocks(300, false);
-	net.peer_mut(2).chain.add_blocks(300, false);
-	net.peer_mut(0).chain.add_blocks(100, true); //fork
-	net.peer_mut(1).chain.add_blocks(200, false);
-	net.peer_mut(2).chain.add_blocks(200, false);
-	net.peer_mut(1).chain.add_blocks(100, false); //fork between 1 and 2
-	net.peer_mut(2).chain.add_blocks(10, true);
-	// peer 1 has the best chain of 601 blocks
-	let peer1_chain = net.peer(1).chain.numbers.read().unwrap().clone();
-	net.sync();
-	assert_eq!(net.peer(0).chain.numbers.read().unwrap().deref(), &peer1_chain);
-	assert_eq!(net.peer(1).chain.numbers.read().unwrap().deref(), &peer1_chain);
-	assert_eq!(net.peer(2).chain.numbers.read().unwrap().deref(), &peer1_chain);
-}
-
-#[test]
-fn chain_restart() {
-	let mut net = TestNet::new(3);
-	net.peer_mut(1).chain.add_blocks(1000, false);
-	net.peer_mut(2).chain.add_blocks(1000, false);
-
-	net.sync_steps(8);
-
-	// make sure that sync has actually happened
-	assert!(net.peer(0).chain.chain_info().best_block_number > 100);
-	net.restart_peer(0);
-
-	let status = net.peer(0).sync.status();
-	assert_eq!(status.state, SyncState::NotSynced);
-}
-
-#[test]
-fn chain_status_empty() {
-	let net = TestNet::new(2);
-	assert_eq!(net.peer(0).sync.status().state, SyncState::NotSynced);
-}
\ No newline at end of file
diff --git a/sync/src/tests/mod.rs b/sync/src/tests/mod.rs
new file mode 100644
index 000000000..a5fa44b04
--- /dev/null
+++ b/sync/src/tests/mod.rs
@@ -0,0 +1,2 @@
+pub mod helpers;
+mod chain;
\ No newline at end of file