client.rs

		let a3 = client.new_block_at(&BlockId::Hash(a2.hash())).unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, a3.clone()).unwrap();

		// A3 -> A4
		let a4 = client.new_block_at(&BlockId::Hash(a3.hash())).unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, a4.clone()).unwrap();

		// A4 -> A5
		let a5 = client.new_block_at(&BlockId::Hash(a4.hash())).unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, a5.clone()).unwrap();

		// A1 -> B2
		let mut builder = client.new_block_at(&BlockId::Hash(a1.hash())).unwrap();
		// this push is required as otherwise B2 has the same hash as A2 and won't get imported
		builder.push_transfer(Transfer {
			from: AccountKeyring::Alice.into(),
			to: AccountKeyring::Ferdie.into(),
			amount: 41,
			nonce: 0,
		}).unwrap();
		let b2 = builder.bake().unwrap();
		client.import(BlockOrigin::Own, b2.clone()).unwrap();

		// B2 -> B3
		let b3 = client.new_block_at(&BlockId::Hash(b2.hash())).unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, b3.clone()).unwrap();

		// B3 -> B4
		let b4 = client.new_block_at(&BlockId::Hash(b3.hash())).unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, b4.clone()).unwrap();

		// // B2 -> C3
		let mut builder = client.new_block_at(&BlockId::Hash(b2.hash())).unwrap();
		// this push is required as otherwise C3 has the same hash as B3 and won't get imported
		builder.push_transfer(Transfer {
			from: AccountKeyring::Alice.into(),
			to: AccountKeyring::Ferdie.into(),
			amount: 1,
			nonce: 1,
		}).unwrap();
		let c3 = builder.bake().unwrap();
		client.import(BlockOrigin::Own, c3.clone()).unwrap();

		// A1 -> D2
		let mut builder = client.new_block_at(&BlockId::Hash(a1.hash())).unwrap();
		// this push is required as otherwise D2 has the same hash as B2 and won't get imported
		builder.push_transfer(Transfer {
			from: AccountKeyring::Alice.into(),
			to: AccountKeyring::Ferdie.into(),
			amount: 1,
			nonce: 0,
		}).unwrap();
		let d2 = builder.bake().unwrap();
		client.import(BlockOrigin::Own, d2.clone()).unwrap();

		assert_eq!(client.info().unwrap().chain.best_hash, a5.hash());

		let genesis_hash = client.info().unwrap().chain.genesis_hash;
		let longest_chain_select = test_client::client::LongestChain::new(
				Arc::new(client.backend().as_in_memory()),
				client.import_lock());

		let leaves = longest_chain_select.leaves().unwrap();

		assert!(leaves.contains(&a5.hash()));
		assert!(leaves.contains(&b4.hash()));
		assert!(leaves.contains(&c3.hash()));
		assert!(leaves.contains(&d2.hash()));
		assert_eq!(leaves.len(), 4);

		// search without restriction

		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			genesis_hash, None).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a1.hash(), None).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a2.hash(), None).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a3.hash(), None).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a4.hash(), None).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a5.hash(), None).unwrap().unwrap());

		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b2.hash(), None).unwrap().unwrap());
		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b3.hash(), None).unwrap().unwrap());
		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b4.hash(), None).unwrap().unwrap());

		assert_eq!(c3.hash(), longest_chain_select.finality_target(
			c3.hash(), None).unwrap().unwrap());

		assert_eq!(d2.hash(), longest_chain_select.finality_target(
			d2.hash(), None).unwrap().unwrap());


		// search only blocks with number <= 5. equivalent to without restriction for this scenario

		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			genesis_hash, Some(5)).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a1.hash(), Some(5)).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a2.hash(), Some(5)).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a3.hash(), Some(5)).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a4.hash(), Some(5)).unwrap().unwrap());
		assert_eq!(a5.hash(), longest_chain_select.finality_target(
			a5.hash(), Some(5)).unwrap().unwrap());

		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b2.hash(), Some(5)).unwrap().unwrap());
		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b3.hash(), Some(5)).unwrap().unwrap());
		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b4.hash(), Some(5)).unwrap().unwrap());

		assert_eq!(c3.hash(), longest_chain_select.finality_target(
			c3.hash(), Some(5)).unwrap().unwrap());

		assert_eq!(d2.hash(), longest_chain_select.finality_target(
			d2.hash(), Some(5)).unwrap().unwrap());


		// search only blocks with number <= 4

		assert_eq!(a4.hash(), longest_chain_select.finality_target(
			genesis_hash, Some(4)).unwrap().unwrap());
		assert_eq!(a4.hash(), longest_chain_select.finality_target(
			a1.hash(), Some(4)).unwrap().unwrap());
		assert_eq!(a4.hash(), longest_chain_select.finality_target(
			a2.hash(), Some(4)).unwrap().unwrap());
		assert_eq!(a4.hash(), longest_chain_select.finality_target(
			a3.hash(), Some(4)).unwrap().unwrap());
		assert_eq!(a4.hash(), longest_chain_select.finality_target(
			a4.hash(), Some(4)).unwrap().unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a5.hash(), Some(4)).unwrap());

		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b2.hash(), Some(4)).unwrap().unwrap());
		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b3.hash(), Some(4)).unwrap().unwrap());
		assert_eq!(b4.hash(), longest_chain_select.finality_target(
			b4.hash(), Some(4)).unwrap().unwrap());

		assert_eq!(c3.hash(), longest_chain_select.finality_target(
			c3.hash(), Some(4)).unwrap().unwrap());

		assert_eq!(d2.hash(), longest_chain_select.finality_target(
			d2.hash(), Some(4)).unwrap().unwrap());


		// search only blocks with number <= 3

		assert_eq!(a3.hash(), longest_chain_select.finality_target(
			genesis_hash, Some(3)).unwrap().unwrap());
		assert_eq!(a3.hash(), longest_chain_select.finality_target(
			a1.hash(), Some(3)).unwrap().unwrap());
		assert_eq!(a3.hash(), longest_chain_select.finality_target(
			a2.hash(), Some(3)).unwrap().unwrap());
		assert_eq!(a3.hash(), longest_chain_select.finality_target(
			a3.hash(), Some(3)).unwrap().unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a4.hash(), Some(3)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a5.hash(), Some(3)).unwrap());

		assert_eq!(b3.hash(), longest_chain_select.finality_target(
			b2.hash(), Some(3)).unwrap().unwrap());
		assert_eq!(b3.hash(), longest_chain_select.finality_target(
			b3.hash(), Some(3)).unwrap().unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			b4.hash(), Some(3)).unwrap());

		assert_eq!(c3.hash(), longest_chain_select.finality_target(
			c3.hash(), Some(3)).unwrap().unwrap());

		assert_eq!(d2.hash(), longest_chain_select.finality_target(
			d2.hash(), Some(3)).unwrap().unwrap());


		// search only blocks with number <= 2

		assert_eq!(a2.hash(), longest_chain_select.finality_target(
			genesis_hash, Some(2)).unwrap().unwrap());
		assert_eq!(a2.hash(), longest_chain_select.finality_target(
			a1.hash(), Some(2)).unwrap().unwrap());
		assert_eq!(a2.hash(), longest_chain_select.finality_target(
			a2.hash(), Some(2)).unwrap().unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a3.hash(), Some(2)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a4.hash(), Some(2)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a5.hash(), Some(2)).unwrap());

		assert_eq!(b2.hash(), longest_chain_select.finality_target(
			b2.hash(), Some(2)).unwrap().unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			b3.hash(), Some(2)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			b4.hash(), Some(2)).unwrap());

		assert_eq!(None, longest_chain_select.finality_target(
			c3.hash(), Some(2)).unwrap());

		assert_eq!(d2.hash(), longest_chain_select.finality_target(
			d2.hash(), Some(2)).unwrap().unwrap());


		// search only blocks with number <= 1

		assert_eq!(a1.hash(), longest_chain_select.finality_target(
			genesis_hash, Some(1)).unwrap().unwrap());
		assert_eq!(a1.hash(), longest_chain_select.finality_target(
			a1.hash(), Some(1)).unwrap().unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a2.hash(), Some(1)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a3.hash(), Some(1)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a4.hash(), Some(1)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a5.hash(), Some(1)).unwrap());

		assert_eq!(None, longest_chain_select.finality_target(
			b2.hash(), Some(1)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			b3.hash(), Some(1)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			b4.hash(), Some(1)).unwrap());

		assert_eq!(None, longest_chain_select.finality_target(
			c3.hash(), Some(1)).unwrap());

		assert_eq!(None, longest_chain_select.finality_target(
			d2.hash(), Some(1)).unwrap());

		// search only blocks with number <= 0

		assert_eq!(genesis_hash, longest_chain_select.finality_target(
			genesis_hash, Some(0)).unwrap().unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a1.hash(), Some(0)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a2.hash(), Some(0)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a3.hash(), Some(0)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a4.hash(), Some(0)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			a5.hash(), Some(0)).unwrap());

		assert_eq!(None, longest_chain_select.finality_target(
			b2.hash(), Some(0)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			b3.hash(), Some(0)).unwrap());
		assert_eq!(None, longest_chain_select.finality_target(
			b4.hash(), Some(0)).unwrap());

		assert_eq!(None, longest_chain_select.finality_target(
			c3.hash().clone(), Some(0)).unwrap());

		assert_eq!(None, longest_chain_select.finality_target(
			d2.hash().clone(), Some(0)).unwrap());
	}

	#[test]
	fn best_containing_on_longest_chain_with_max_depth_higher_than_best() {
		// block tree:
		// G -> A1 -> A2

		let client = test_client::new();

		// G -> A1
		let a1 = client.new_block().unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, a1.clone()).unwrap();

		// A1 -> A2
		let a2 = client.new_block().unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, a2.clone()).unwrap();

		let genesis_hash = client.info().unwrap().chain.genesis_hash;
		let longest_chain_select = test_client::client::LongestChain::new(
			Arc::new(client.backend().as_in_memory()),
			client.import_lock()
		);

		assert_eq!(a2.hash(), longest_chain_select.finality_target(
			genesis_hash, Some(10)).unwrap().unwrap());
	}

	#[test]
	fn key_changes_works() {
		let (client, _, test_cases) = prepare_client_with_key_changes();

		for (index, (begin, end, key, expected_result)) in test_cases.into_iter().enumerate() {
			let end = client.block_hash(end).unwrap().unwrap();
			let actual_result = client.key_changes(begin, BlockId::Hash(end), &StorageKey(key)).unwrap();
			match actual_result == expected_result {
				true => (),
				false => panic!(format!("Failed test {}: actual = {:?}, expected = {:?}",
					index, actual_result, expected_result)),
			}
		}
	}

	#[test]
	fn import_with_justification() {
		use test_client::blockchain::Backend;

		let client = test_client::new();

		// G -> A1
		let a1 = client.new_block().unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, a1.clone()).unwrap();

		// A1 -> A2
		let a2 = client.new_block_at(&BlockId::Hash(a1.hash())).unwrap().bake().unwrap();
		client.import(BlockOrigin::Own, a2.clone()).unwrap();

		// A2 -> A3
		let justification = vec![1, 2, 3];
		let a3 = client.new_block_at(&BlockId::Hash(a2.hash())).unwrap().bake().unwrap();
		client.import_justified(BlockOrigin::Own, a3.clone(), justification.clone()).unwrap();

		assert_eq!(
			client.backend().blockchain().last_finalized().unwrap(),
			a3.hash(),
		);

		assert_eq!(
			client.backend().blockchain().justification(BlockId::Hash(a3.hash())).unwrap(),
			Some(justification),
		);

		assert_eq!(
			client.backend().blockchain().justification(BlockId::Hash(a1.hash())).unwrap(),
			None,
		);

		assert_eq!(
			client.backend().blockchain().justification(BlockId::Hash(a2.hash())).unwrap(),
			None,
		);
	}
}