Punish offline validators, aura-style (#1216)

* make offline-reporting infrastructure more generic

* add a listener-trait for watching when the timestamp has been set

* prevent inclusion of empty offline reports

* add test for exclusion

* generate aura-offline reports

* ability to slash many times for being offline "multiple" times

* Logic for punishing validators for missing aura steps

* stub tests

* pave way for verification of timestamp vs slot

* alter aura import queue to wait for timestamp

* check timestamp matches seal

* do inherent check properly

* service compiles

* all tests compile

* test srml-aura logic

* aura tests pass

* everything builds

* some more final tweaks to block authorship for aura

* switch to manual delays before step

* restore substrate-consensus-aura to always std and address grumbles

* update some state roots in executor tests

* node-executor tests pass

* get most tests passing

* address grumbles

substrate/srml/aura/src/mock.rs

@@ -0,0 +1,78 @@
+// Copyright 2018 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Test utilities
+
+#![cfg(test)]
+
+use primitives::{BuildStorage, testing::{Digest, DigestItem, Header}};
+use runtime_io;
+use substrate_primitives::{H256, Blake2Hasher};
+use {Trait, Module, consensus, system, timestamp};
+
+impl_outer_origin!{
+	pub enum Origin for Test {}
+}
+
+// Workaround for https://github.com/rust-lang/rust/issues/26925 . Remove when sorted.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Test;
+
+impl consensus::Trait for Test {
+	const NOTE_OFFLINE_POSITION: u32 = 1;
+	type Log = DigestItem;
+	type SessionKey = u64;
+	type InherentOfflineReport = ();
+}
+
+impl system::Trait for Test {
+	type Origin = Origin;
+	type Index = u64;
+	type BlockNumber = u64;
+	type Hash = H256;
+	type Hashing = ::primitives::traits::BlakeTwo256;
+	type Digest = Digest;
+	type AccountId = u64;
+	type Header = Header;
+	type Event = ();
+	type Log = DigestItem;
+}
+
+impl timestamp::Trait for Test {
+	const TIMESTAMP_SET_POSITION: u32 = 0;
+
+	type Moment = u64;
+	type OnTimestampSet = Aura;
+}
+
+impl Trait for Test {
+	type HandleReport = ();
+}
+
+pub fn new_test_ext(authorities: Vec<u64>) -> runtime_io::TestExternalities<Blake2Hasher> {
+	let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
+	t.extend(consensus::GenesisConfig::<Test>{
+		code: vec![],
+		authorities,
+	}.build_storage().unwrap().0);
+	t.extend(timestamp::GenesisConfig::<Test>{
+		period: 1,
+	}.build_storage().unwrap().0);
+	t.into()
+}
+
+pub type System = system::Module<Test>;
+pub type Aura = Module<Test>;