Fixing BABE epochs to change between blocks (#3583)

* always fetch epoch from runtime

* node integration tests don't test light nodes

* give stand-in full node a FULL role

* rejig babe APIs

* introduce next-epoch-descriptor type

* overhaul srml-BABE epoch logic

* ensure VRF outputs end up in the right epoch-randomness

* rewrite `do_initialize` to remove unnecessary loop

* begin accounting for next epoch in epoch function

* slots passes header to epoch_data

* pass slot_number to SlotWorker::epoch_data

* begin extracting epoch-change logic into its own module

* aux methods for block weight

* aux methods for genesis configuration

* comment-out most, refactor header-check pipeline

* mostly flesh out verifier again

* reinstantiate babe BlockImport implementation

* reinstate import-queue instantiation

* reintroduce slot-worker implementation

* reinstate pretty much all the rest

* move fork-choice logic to BlockImport

* fix some, but not all errors

* patch test-runtime

* make is_descendent of slightly more generic

* get skeleton compiling when passing is_descendent_of

* make descendent-of-builder more succinct

* restore ordering of authority_index / slot_number

* start fiddling with tests

* fix warnings

* improve initialization architecture and handle genesis

* tests use correct block-import

* fix BABE tests

* fix some compiler errors

* fix node-cli compilation

* all crates compile

* bump runtime versions and fix some warnings

* tweak fork-tree search implementation

* do backtracking search in fork-tree

* node-cli integration tests now work

* fix broken assumption in test_connectivity

* babe tests fail for the right reasons.

* test genesis epoch logic for epoch_changes

* test that epochs can change between blocks

* First BABE SRML test

* Testing infrastructure for BABE

Also includes a trivial additional test.

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* A little more test progress

* More work on BABE testing

* Try to get the tests working

* Implement `UintAuthorityId`-based test mocks

* Fix compilation errors

* Adjust to upstream changes

* Block numbers are ignored in BABE epoch calculation

* authority_index() should ignore invalid authorities

* Fix compile error

* Add tests that session transitions happen

* Check if BABE produces logs

It currently does not.

* Fix test suite

This was really nasty, due to a type confusion that showed up as an
off-by-1 buffer error.

* Add additional tests

Most of these were derived from the current output, so they are only
useful to guard against regressions.

* Make the tests more readable

Also bump impl_version.

* Fix excessive line width

* Remove unused imports

* Update srml/babe/src/lib.rs

Co-Authored-By: André Silva <andre.beat@gmail.com>

* try to fix imports

* Fix build errors in test suite

* tests did not pass

* Try to get at least one digest to be output

Currently, the code emits either no digests (if I don’t call
`Session::rotate_session()` or two digests (if I do), which is wrong.

* More tests

They still don’t work, but this should help debugging.

* fix silly error

* Don’t even try to compile a broken test

* remove broken check_epoch test and add one for genesis epoch

* Check that the length of the pre-digests is correct

* Bump `impl_version`

* use epoch_for_descendent_of even for genesis

* account for competing block 1s

* finish srml-babe docs

Co-Authored-By: André Silva <andre.beat@gmail.com>

* address grumbles

substrate/core/network/src/test/mod.rs

@@ -461,7 +461,12 @@ pub trait TestNetFactory: Sized {
 
 	/// These two need to be implemented!
 	fn from_config(config: &ProtocolConfig) -> Self;
-	fn make_verifier(&self, client: PeersClient, config: &ProtocolConfig) -> Self::Verifier;
+	fn make_verifier(
+		&self,
+		client: PeersClient,
+		config: &ProtocolConfig,
+		peer_data: &Self::PeerData,
+	) -> Self::Verifier;
 
 	/// Get reference to peer.
 	fn peer(&mut self, i: usize) -> &mut Peer<Self::PeerData, Self::Specialization>;
@@ -509,12 +514,23 @@ pub trait TestNetFactory: Sized {
 		let backend = test_client_builder.backend();
 		let (c, longest_chain) = test_client_builder.build_with_longest_chain();
 		let client = Arc::new(c);
-		let verifier = self.make_verifier(PeersClient::Full(client.clone(), backend.clone()), config);
-		let verifier = VerifierAdapter(Arc::new(Mutex::new(Box::new(verifier) as Box<_>)));
-		let (block_import, justification_import, finality_proof_import, finality_proof_request_builder, data)
-			= self.make_block_import(PeersClient::Full(client.clone(), backend.clone()));
+
+		let (
+			block_import,
+			justification_import,
+			finality_proof_import,
+			finality_proof_request_builder,
+			data,
+		) = self.make_block_import(PeersClient::Full(client.clone(), backend.clone()));
 		let block_import = BlockImportAdapter(Arc::new(Mutex::new(block_import)));
 
+		let verifier = self.make_verifier(
+			PeersClient::Full(client.clone(), backend.clone()),
+			config,
+			&data,
+		);
+		let verifier = VerifierAdapter(Arc::new(Mutex::new(Box::new(verifier) as Box<_>)));
+
 		let import_queue = Box::new(BasicQueue::new(
 			verifier.clone(),
 			Box::new(block_import.clone()),
@@ -572,12 +588,22 @@ pub trait TestNetFactory: Sized {
 
 		let (c, backend) = test_client::new_light();
 		let client = Arc::new(c);
-		let verifier = self.make_verifier(PeersClient::Light(client.clone(), backend.clone()), &config);
-		let verifier = VerifierAdapter(Arc::new(Mutex::new(Box::new(verifier) as Box<_>)));
-		let (block_import, justification_import, finality_proof_import, finality_proof_request_builder, data)
-			= self.make_block_import(PeersClient::Light(client.clone(), backend.clone()));
+		let (
+			block_import,
+			justification_import,
+			finality_proof_import,
+			finality_proof_request_builder,
+			data,
+		) = self.make_block_import(PeersClient::Light(client.clone(), backend.clone()));
 		let block_import = BlockImportAdapter(Arc::new(Mutex::new(block_import)));
 
+		let verifier = self.make_verifier(
+			PeersClient::Light(client.clone(), backend.clone()),
+			&config,
+			&data,
+		);
+		let verifier = VerifierAdapter(Arc::new(Mutex::new(Box::new(verifier) as Box<_>)));
+
 		let import_queue = Box::new(BasicQueue::new(
 			verifier.clone(),
 			Box::new(block_import.clone()),
@@ -696,7 +722,7 @@ impl TestNetFactory for TestNet {
 		}
 	}
 
-	fn make_verifier(&self, _client: PeersClient, _config: &ProtocolConfig)
+	fn make_verifier(&self, _client: PeersClient, _config: &ProtocolConfig, _peer_data: &())
 		-> Self::Verifier
 	{
 		PassThroughVerifier(false)
@@ -742,8 +768,8 @@ impl TestNetFactory for JustificationTestNet {
 		JustificationTestNet(TestNet::from_config(config))
 	}
 
-	fn make_verifier(&self, client: PeersClient, config: &ProtocolConfig) -> Self::Verifier {
-		self.0.make_verifier(client, config)
+	fn make_verifier(&self, client: PeersClient, config: &ProtocolConfig, peer_data: &()) -> Self::Verifier {
+		self.0.make_verifier(client, config, peer_data)
 	}
 
 	fn peer(&mut self, i: usize) -> &mut Peer<Self::PeerData, Self::Specialization> {