dry-run mode for init bridge command (#1690)

* `dry-run` mode for init bridge command

* fix clippy

bridges/primitives/messages/src/target_chain.rs

@@ -90,7 +90,7 @@ pub trait MessageDispatch<AccountId> {
 	type DispatchPayload: Decode;
 
 	/// Fine-grained result of single message dispatch (for better diagnostic purposes)
-	type DispatchLevelResult: Clone + Decode + sp_std::fmt::Debug + Eq;
+	type DispatchLevelResult: Clone + sp_std::fmt::Debug + Eq;
 
 	/// Estimate dispatch weight.
 	///

bridges/relays/bin-substrate/src/cli/init_bridge.rs

@@ -15,6 +15,7 @@
 // along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
 
 use async_trait::async_trait;
+use codec::Encode;
 
 use crate::{
 	chains::{
@@ -46,6 +47,9 @@ pub struct InitBridge {
 	target: TargetConnectionParams,
 	#[structopt(flatten)]
 	target_sign: TargetSigningParams,
+	/// Generates all required data, but does not submit extrinsic
+	#[structopt(long)]
+	dry_run: bool,
 }
 
 #[derive(Debug, EnumString, EnumVariantNames)]
@@ -77,6 +81,7 @@ where
 		let source_client = data.source.into_client::<Self::Source>().await?;
 		let target_client = data.target.into_client::<Self::Target>().await?;
 		let target_sign = data.target_sign.to_keypair::<Self::Target>()?;
+		let dry_run = data.dry_run;
 
 		let (spec_version, transaction_version) = target_client.simple_runtime_version().await?;
 		substrate_relay_helper::finality::initialize::initialize::<Self::Engine, _, _, _>(
@@ -90,11 +95,15 @@ where
 				signer: target_sign,
 			},
 			move |transaction_nonce, initialization_data| {
-				Ok(UnsignedTransaction::new(
-					Self::encode_init_bridge(initialization_data).into(),
-					transaction_nonce,
-				))
+				let call = Self::encode_init_bridge(initialization_data);
+				log::info!(
+					target: "bridge",
+					"Initialize bridge call encoded as hex string: {:?}",
+					format!("0x{}", hex::encode(call.encode()))
+				);
+				Ok(UnsignedTransaction::new(call.into(), transaction_nonce))
 			},
+			dry_run,
 		)
 		.await;
 

bridges/relays/lib-substrate-relay/src/finality/initialize.rs

@@ -40,6 +40,7 @@ pub async fn initialize<
 	target_transactions_signer: TargetChain::AccountId,
 	target_signing_data: SignParam<TargetChain>,
 	prepare_initialize_transaction: F,
+	dry_run: bool,
 ) where
 	F: FnOnce(
 			TargetChain::Index,
@@ -54,6 +55,7 @@ pub async fn initialize<
 		target_transactions_signer,
 		target_signing_data,
 		prepare_initialize_transaction,
+		dry_run,
 	)
 	.await;
 
@@ -88,6 +90,7 @@ async fn do_initialize<
 	target_transactions_signer: TargetChain::AccountId,
 	target_signing_data: SignParam<TargetChain>,
 	prepare_initialize_transaction: F,
+	dry_run: bool,
 ) -> Result<
 	Option<TargetChain::Hash>,
 	Error<SourceChain::Hash, <SourceChain::Header as HeaderT>::Number>,
@@ -110,7 +113,9 @@ where
 			SourceChain::NAME,
 			TargetChain::NAME,
 		);
-		return Ok(None)
+		if !dry_run {
+			return Ok(None)
+		}
 	}
 
 	let initialization_data = E::prepare_initialization_data(source_client).await?;
@@ -127,7 +132,14 @@ where
 			target_transactions_signer,
 			target_signing_data,
 			move |_, transaction_nonce| {
-				prepare_initialize_transaction(transaction_nonce, initialization_data)
+				let tx = prepare_initialize_transaction(transaction_nonce, initialization_data);
+				if dry_run {
+					Err(SubstrateError::Custom(
+						"Not submitting extrinsic in `dry-run` mode!".to_string(),
+					))
+				} else {
+					tx
+				}
 			},
 		)
 		.await