verify that GRANDPA pallet is not initialized before submitting initialization transaction (#1267)

* verify that GRANDPA pallet is not initialized before submitting initialization transaction

* spelling

bridges/relays/client-substrate/src/chain.rs

@@ -64,6 +64,20 @@ pub trait Chain: ChainBase + Clone {
 	type WeightToFee: WeightToFeePolynomial<Balance = Self::Balance>;
 }
 
+/// Substrate-based chain that is using direct GRANDPA finality from minimal relay-client point of
+/// view.
+///
+/// Keep in mind that parachains are relying on relay chain GRANDPA, so they should not implement
+/// this trait.
+pub trait ChainWithGrandpa: Chain {
+	/// Name of the bridge GRANDPA pallet (used in `construct_runtime` macro call) that is deployed
+	/// at some other chain to bridge with this `ChainWithGrandpa`.
+	///
+	/// We assume that all chains that are bridging with this `ChainWithGrandpa` are using
+	/// the same name.
+	const WITH_CHAIN_GRANDPA_PALLET_NAME: &'static str;
+}
+
 /// Substrate-based chain with messaging support from minimal relay-client point of view.
 pub trait ChainWithMessages: Chain {
 	/// Name of the bridge messages pallet (used in `construct_runtime` macro call) that is deployed

bridges/relays/client-substrate/src/lib.rs

@@ -32,7 +32,7 @@ use std::time::Duration;
 pub use crate::{
 	chain::{
 		AccountKeyPairOf, BlockWithJustification, CallOf, Chain, ChainWithBalances,
-		ChainWithMessages, SignParam, TransactionSignScheme, TransactionStatusOf,
+		ChainWithGrandpa, ChainWithMessages, SignParam, TransactionSignScheme, TransactionStatusOf,
 		UnsignedTransaction, WeightToFeeOf,
 	},
 	client::{ChainRuntimeVersion, Client, OpaqueGrandpaAuthoritiesSet, Subscription},