Collator for the "adder" (formerly basic-add) parachain and various small fixes (#438)

* update basic_add wasm

* wasm feature and collator feature

* move test parachains around a little

* fix wasm build for basic_add

* move basic_add to adder, introduce README

* minimal basic_add collator

* ensure collator messages are sent in the right order

* more logging

* route consensus statements to all peers

* minor bugfixes for parachains

* genesis builder accounts for parachain heads

* fix parachains tests

* targets for txpool

* tweak runtime + collator

* fix version in adder-collator

* consistency for overflowing

* adjust comment

* fix stable test run

* remove dummy registration test

* final grumbles

polkadot/parachain/tests/adder.rs

@@ -0,0 +1,166 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Basic parachain that adds a number as part of its state.
+
+extern crate polkadot_parachain as parachain;
+extern crate tiny_keccak;
+
+use parachain::ValidationParams;
+use parachain::codec::{Decode, Encode, Input, Output};
+
+// Head data for this parachain.
+#[derive(Default, Clone)]
+struct HeadData {
+	// Block number
+	number: u64,
+	// parent block keccak256
+	parent_hash: [u8; 32],
+	// hash of post-execution state.
+	post_state: [u8; 32],
+}
+
+impl Encode for HeadData {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
+		dest.push(&self.number);
+		dest.push(&self.parent_hash);
+		dest.push(&self.post_state);
+	}
+}
+
+impl Decode for HeadData {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
+		Some(HeadData {
+			number: Decode::decode(input)?,
+			parent_hash: Decode::decode(input)?,
+			post_state: Decode::decode(input)?,
+		})
+	}
+}
+
+// Block data for this parachain.
+#[derive(Default, Clone)]
+struct BlockData {
+	// State to begin from.
+	state: u64,
+	// Amount to add (overflowing)
+	add: u64,
+}
+
+impl Encode for BlockData {
+	fn encode_to<T: Output>(&self, dest: &mut T) {
+		dest.push(&self.state);
+		dest.push(&self.add);
+	}
+}
+
+impl Decode for BlockData {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
+		Some(BlockData {
+			state: Decode::decode(input)?,
+			add: Decode::decode(input)?,
+		})
+	}
+}
+
+const TEST_CODE: &[u8] = include_bytes!("res/adder.wasm");
+
+fn hash_state(state: u64) -> [u8; 32] {
+	::tiny_keccak::keccak256(state.encode().as_slice())
+}
+
+fn hash_head(head: &HeadData) -> [u8; 32] {
+	::tiny_keccak::keccak256(head.encode().as_slice())
+}
+
+#[test]
+fn execute_good_on_parent() {
+	let parent_head = HeadData {
+		number: 0,
+		parent_hash: [0; 32],
+		post_state: hash_state(0),
+	};
+
+	let block_data = BlockData {
+		state: 0,
+		add: 512,
+	};
+
+	let ret = parachain::wasm::validate_candidate(TEST_CODE, ValidationParams {
+		parent_head: parent_head.encode(),
+		block_data: block_data.encode(),
+	}).unwrap();
+
+	let new_head = HeadData::decode(&mut &ret.head_data[..]).unwrap();
+
+	assert_eq!(new_head.number, 1);
+	assert_eq!(new_head.parent_hash, hash_head(&parent_head));
+	assert_eq!(new_head.post_state, hash_state(512));
+}
+
+#[test]
+fn execute_good_chain_on_parent() {
+	let mut number = 0;
+	let mut parent_hash = [0; 32];
+	let mut last_state = 0;
+
+	for add in 0..10 {
+		let parent_head = HeadData {
+			number,
+			parent_hash,
+			post_state: hash_state(last_state),
+		};
+
+		let block_data = BlockData {
+			state: last_state,
+			add,
+		};
+
+		let ret = parachain::wasm::validate_candidate(TEST_CODE, ValidationParams {
+			parent_head: parent_head.encode(),
+			block_data: block_data.encode(),
+		}).unwrap();
+
+		let new_head = HeadData::decode(&mut &ret.head_data[..]).unwrap();
+
+		assert_eq!(new_head.number, number + 1);
+		assert_eq!(new_head.parent_hash, hash_head(&parent_head));
+		assert_eq!(new_head.post_state, hash_state(last_state + add));
+
+		number += 1;
+		parent_hash = hash_head(&new_head);
+		last_state += add;
+	}
+}
+
+#[test]
+fn execute_bad_on_parent() {
+		let parent_head = HeadData {
+		number: 0,
+		parent_hash: [0; 32],
+		post_state: hash_state(0),
+	};
+
+	let block_data = BlockData {
+		state: 256, // start state is wrong.
+		add: 256,
+	};
+
+	let _ret = parachain::wasm::validate_candidate(TEST_CODE, ValidationParams {
+		parent_head: parent_head.encode(),
+		block_data: block_data.encode(),
+	}).unwrap_err();
+}