Bridges subtree sync (#2991)

* Squashed 'bridges/' changes from 0417308a48..278119fec2

278119fec2 Grandpa: Store the authority set changes (#2336) (#2337)
19f9c8ffdb remove message sender origin (#2322)
3c7c271d2e GRANDPA module: store accepted justifications (#2298) (#2301)
fb7d12e793 GRANDPA justifications: equivocation detection primitives (#2295) (#2297)
d03a2ed450 More backports from Cumulus subtree to polkadot-staging (#2283)
3c4ada921b Update dependecies (#2277) (#2281)
3e195c9e76 GRANDPA: optimize votes_ancestries when needed (#2262) (#2264)
7065bbabc6 Implement RuntimeDebug for GrandpaJustification (#2254)
8c9e59bcbc Define generate_grandpa_key_ownership_proof() (#2247) (#2248)
0b46956df7 Deduplicate Grandpa consensus log reading logic (#2245) (#2246)
96c9701710 Fix deps from Cumulus (#2244)

git-subtree-dir: bridges
git-subtree-split: 278119fec2b45990cf1271999b0c21befe7003d9

* Subtree update

* Squashed 'bridges/' changes from 278119fec2..edf33a2c85

edf33a2c85 Backport fix (for wasm `std` env) (#2339)

git-subtree-dir: bridges
git-subtree-split: edf33a2c85399d366e008228f2d9e63e8a492d95

cumulus/bridges/primitives/header-chain/tests/justification/equivocation.rs

@@ -0,0 +1,124 @@
+// Copyright 2020-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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.
+
+// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Tests for Grandpa equivocations collector code.
+
+use bp_header_chain::justification::EquivocationsCollector;
+use bp_test_utils::*;
+use finality_grandpa::Precommit;
+use sp_consensus_grandpa::EquivocationProof;
+
+type TestHeader = sp_runtime::testing::Header;
+
+#[test]
+fn duplicate_votes_are_not_considered_equivocations() {
+	let voter_set = voter_set();
+	let base_justification = make_default_justification::<TestHeader>(&test_header(1));
+
+	let mut collector =
+		EquivocationsCollector::new(TEST_GRANDPA_SET_ID, &voter_set, &base_justification).unwrap();
+	collector.parse_justification(&base_justification.clone()).unwrap();
+
+	assert_eq!(collector.into_equivocation_proofs().len(), 0);
+}
+
+#[test]
+fn equivocations_are_detected_in_base_justification_redundant_votes() {
+	let voter_set = voter_set();
+	let mut base_justification = make_default_justification::<TestHeader>(&test_header(1));
+
+	let first_vote = base_justification.commit.precommits[0].clone();
+	let equivocation = signed_precommit::<TestHeader>(
+		&ALICE,
+		header_id::<TestHeader>(1),
+		base_justification.round,
+		TEST_GRANDPA_SET_ID,
+	);
+	base_justification.commit.precommits.push(equivocation.clone());
+
+	let collector =
+		EquivocationsCollector::new(TEST_GRANDPA_SET_ID, &voter_set, &base_justification).unwrap();
+
+	assert_eq!(
+		collector.into_equivocation_proofs(),
+		vec![EquivocationProof::new(
+			1,
+			sp_consensus_grandpa::Equivocation::Precommit(finality_grandpa::Equivocation {
+				round_number: 1,
+				identity: ALICE.into(),
+				first: (
+					Precommit {
+						target_hash: first_vote.precommit.target_hash,
+						target_number: first_vote.precommit.target_number
+					},
+					first_vote.signature
+				),
+				second: (
+					Precommit {
+						target_hash: equivocation.precommit.target_hash,
+						target_number: equivocation.precommit.target_number
+					},
+					equivocation.signature
+				)
+			})
+		)]
+	);
+}
+
+#[test]
+fn equivocations_are_detected_in_extra_justification_redundant_votes() {
+	let voter_set = voter_set();
+	let base_justification = make_default_justification::<TestHeader>(&test_header(1));
+	let first_vote = base_justification.commit.precommits[0].clone();
+
+	let mut extra_justification = base_justification.clone();
+	let equivocation = signed_precommit::<TestHeader>(
+		&ALICE,
+		header_id::<TestHeader>(1),
+		base_justification.round,
+		TEST_GRANDPA_SET_ID,
+	);
+	extra_justification.commit.precommits.push(equivocation.clone());
+
+	let mut collector =
+		EquivocationsCollector::new(TEST_GRANDPA_SET_ID, &voter_set, &base_justification).unwrap();
+	collector.parse_justification(&extra_justification).unwrap();
+
+	assert_eq!(
+		collector.into_equivocation_proofs(),
+		vec![EquivocationProof::new(
+			1,
+			sp_consensus_grandpa::Equivocation::Precommit(finality_grandpa::Equivocation {
+				round_number: 1,
+				identity: ALICE.into(),
+				first: (
+					Precommit {
+						target_hash: first_vote.precommit.target_hash,
+						target_number: first_vote.precommit.target_number
+					},
+					first_vote.signature
+				),
+				second: (
+					Precommit {
+						target_hash: equivocation.precommit.target_hash,
+						target_number: equivocation.precommit.target_number
+					},
+					equivocation.signature
+				)
+			})
+		)]
+	);
+}