ChainSpec extensions (#3692)

* Add some chainspec tests and make sure we validate it.

* Manual implementation of Extension + Forks definitions.

* Move chain spec to separate crate.

* Allow using ChainSpec with extensions.

* Renames.

* Implement Extension derive.

* Implement Extension for Forks.

* Support specifying fork blocks.

* make for_blocks work

* Support forks correctly.

* Add a bunch of docs.

* Make fork blocks optional.

* Add missing docs.

* Fix build.

* Use struct for check_block params.

* Fix tests?

* Clean up.

substrate/node/cli/src/chain_spec.rs

@@ -16,15 +16,16 @@
 
 //! Substrate chain configurations.
 
+use chain_spec::ChainSpecExtension;
 use primitives::{Pair, Public, crypto::UncheckedInto};
-pub use node_primitives::{AccountId, Balance};
+use serde::{Serialize, Deserialize};
 use node_runtime::{
 	AuthorityDiscoveryConfig, BabeConfig, BalancesConfig, ContractsConfig, CouncilConfig, DemocracyConfig,
 	ElectionsConfig, GrandpaConfig, ImOnlineConfig, IndicesConfig, SessionConfig, SessionKeys, StakerStatus,
 	StakingConfig, SudoConfig, SystemConfig, TechnicalCommitteeConfig, WASM_BINARY,
 };
+use node_runtime::Block;
 use node_runtime::constants::{time::*, currency::*};
-pub use node_runtime::GenesisConfig;
 use substrate_service;
 use hex_literal::hex;
 use substrate_telemetry::TelemetryEndpoints;
@@ -33,11 +34,26 @@ use babe_primitives::{AuthorityId as BabeId};
 use im_online::sr25519::{AuthorityId as ImOnlineId};
 use sr_primitives::Perbill;
 
+pub use node_primitives::{AccountId, Balance};
+pub use node_runtime::GenesisConfig;
+
 const STAGING_TELEMETRY_URL: &str = "wss://telemetry.polkadot.io/submit/";
 
-/// Specialized `ChainSpec`.
-pub type ChainSpec = substrate_service::ChainSpec<GenesisConfig>;
+/// Node `ChainSpec` extensions.
+///
+/// Additional parameters for some Substrate core modules,
+/// customizable from the chain spec.
+#[derive(Default, Clone, Serialize, Deserialize, ChainSpecExtension)]
+pub struct Extensions {
+	/// Block numbers with known hashes.
+	pub fork_blocks: client::ForkBlocks<Block>,
+}
 
+/// Specialized `ChainSpec`.
+pub type ChainSpec = substrate_service::ChainSpec<
+	GenesisConfig,
+	Extensions,
+>;
 /// Flaming Fir testnet generator
 pub fn flaming_fir_config() -> Result<ChainSpec, String> {
 	ChainSpec::from_json_bytes(&include_bytes!("../res/flaming-fir.json")[..])
@@ -191,7 +207,7 @@ pub fn staging_testnet_config() -> ChainSpec {
 		Some(TelemetryEndpoints::new(vec![(STAGING_TELEMETRY_URL.to_string(), 0)])),
 		None,
 		None,
-		None,
+		Default::default(),
 	)
 }
 
@@ -327,7 +343,16 @@ fn development_config_genesis() -> GenesisConfig {
 
 /// Development config (single validator Alice)
 pub fn development_config() -> ChainSpec {
-	ChainSpec::from_genesis("Development", "dev", development_config_genesis, vec![], None, None, None, None)
+	ChainSpec::from_genesis(
+		"Development",
+		"dev",
+		development_config_genesis,
+		vec![],
+		None,
+		None,
+		None,
+		Default::default(),
+	)
 }
 
 fn local_testnet_genesis() -> GenesisConfig {
@@ -344,7 +369,16 @@ fn local_testnet_genesis() -> GenesisConfig {
 
 /// Local testnet config (multivalidator Alice + Bob)
 pub fn local_testnet_config() -> ChainSpec {
-	ChainSpec::from_genesis("Local Testnet", "local_testnet", local_testnet_genesis, vec![], None, None, None, None)
+	ChainSpec::from_genesis(
+		"Local Testnet",
+		"local_testnet",
+		local_testnet_genesis,
+		vec![],
+		None,
+		None,
+		None,
+		Default::default(),
+	)
 }
 
 #[cfg(test)]
@@ -375,7 +409,7 @@ pub(crate) mod tests {
 			None,
 			None,
 			None,
-			None,
+			Default::default(),
 		)
 	}
 
@@ -389,7 +423,7 @@ pub(crate) mod tests {
 			None,
 			None,
 			None,
-			None,
+			Default::default(),
 		)
 	}