Inject hashed prefix for remote-ext (#8960)

* Inject for remote-ext

* Update utils/frame/remote-externalities/src/lib.rs

Co-authored-by: Zeke Mostov <32168567+emostov@users.noreply.github.com>

* Update utils/frame/remote-externalities/src/lib.rs

Co-authored-by: Zeke Mostov <32168567+emostov@users.noreply.github.com>

* Apply suggestions from code review

* Apply suggestions from code review

Co-authored-by: Zeke Mostov <32168567+emostov@users.noreply.github.com>

substrate/frame/system/src/offchain.rs

@@ -447,7 +447,7 @@ pub trait AppCrypto<Public, Signature> {
 // TODO [#5663] Could this be just `T::Signature as traits::Verify>::Signer`?
 // Seems that this may cause issues with bounds resolution.
 pub trait SigningTypes: crate::Config {
-	/// A public key that is capable of identifing `AccountId`s.
+	/// A public key that is capable of identifying `AccountId`s.
 	///
 	/// Usually that's either a raw crypto public key (e.g. `sr25519::Public`) or
 	/// an aggregate type for multiple crypto public keys, like `MulitSigner`.

substrate/utils/frame/remote-externalities/src/lib.rs

@@ -19,87 +19,6 @@
 //!
 //! An equivalent of `sp_io::TestExternalities` that can load its state from a remote substrate
 //! based chain, or a local state snapshot file.
-//!
-//! #### Runtime to Test Against
-//!
-//! While not absolutely necessary, you most likely need a `Runtime` equivalent in your test setup
-//! through which you can infer storage types. There are two options here:
-//!
-//! 1. Build a mock runtime, similar how to you would build one in a pallet test (see example
-//!    below). The very important point here is that this mock needs to hold real values for types
-//!    that matter for you, based on the chain of interest. Some typical ones are:
-//!
-//! - `sp_runtime::AccountId32` as `AccountId`.
-//! - `u32` as `BlockNumber`.
-//! - `u128` as Balance.
-//!
-//! Once you have your `Runtime`, you can use it for storage type resolution and do things like
-//! `<my_pallet::Pallet<Runtime>>::storage_getter()` or `<my_pallet::StorageItem<Runtime>>::get()`.
-//!
-//! 2. Or, you can use a real runtime.
-//!
-//! ### Example
-//!
-//! With a test runtime
-//!
-//! ```ignore
-//! use remote_externalities::Builder;
-//!
-//! #[derive(Clone, Eq, PartialEq, Debug, Default)]
-//! pub struct TestRuntime;
-//!
-//! use frame_system as system;
-//! impl_outer_origin! {
-//!     pub enum Origin for TestRuntime {}
-//! }
-//!
-//! impl frame_system::Config for TestRuntime {
-//!     ..
-//!     // we only care about these two for now. The rest can be mock. The block number type of
-//!     // kusama is u32.
-//!     type BlockNumber = u32;
-//!     type Header = Header;
-//!     ..
-//! }
-//!
-//! #[test]
-//! fn test_runtime_works() {
-//!     let hash: Hash =
-//!         hex!["f9a4ce984129569f63edc01b1c13374779f9384f1befd39931ffdcc83acf63a7"].into();
-//!     let parent: Hash =
-//!         hex!["540922e96a8fcaf945ed23c6f09c3e189bd88504ec945cc2171deaebeaf2f37e"].into();
-//!     Builder::new()
-//!         .at(hash)
-//!         .module("System")
-//!         .build()
-//!         .execute_with(|| {
-//!             assert_eq!(
-//!                 // note: the hash corresponds to 3098546. We can check only the parent.
-//!                 // https://polkascan.io/kusama/block/3098546
-//!                 <frame_system::Pallet<Runtime>>::block_hash(3098545u32),
-//!                 parent,
-//!             )
-//!         });
-//! }
-//! ```
-//!
-//! Or with the real kusama runtime.
-//!
-//! ```ignore
-//! use remote_externalities::Builder;
-//! use kusama_runtime::Runtime;
-//!
-//! #[test]
-//! fn test_runtime_works() {
-//!     let hash: Hash =
-//!         hex!["f9a4ce984129569f63edc01b1c13374779f9384f1befd39931ffdcc83acf63a7"].into();
-//!     Builder::new()
-//!         .at(hash)
-//!         .module("Staking")
-//!         .build()
-//!         .execute_with(|| assert_eq!(<pallet_staking::Module<Runtime>>::validator_count(), 400));
-//! }
-//! ```
 
 use std::{
 	fs,
@@ -235,8 +154,10 @@ impl Default for SnapshotConfig {
 
 /// Builder for remote-externalities.
 pub struct Builder<B: BlockT> {
-	/// Pallets to inject their prefix into the externalities.
+	/// Custom key-pairs to be injected into the externalities.
 	inject: Vec<KeyPair>,
+	/// Storage entry key prefixes to be injected into the externalities. The *hashed* prefix must be given.
+	hashed_prefixes: Vec<Vec<u8>>,
 	/// connectivity mode, online or offline.
 	mode: Mode<B>,
 }
@@ -245,7 +166,7 @@ pub struct Builder<B: BlockT> {
 // that.
 impl<B: BlockT> Default for Builder<B> {
 	fn default() -> Self {
-		Self { inject: Default::default(), mode: Default::default() }
+		Self { inject: Default::default(), mode: Default::default(), hashed_prefixes: Default::default() }
 	}
 }
 
@@ -394,7 +315,7 @@ impl<B: BlockT> Builder<B> {
 
 	/// initialize `Self` from state snapshot. Panics if the file does not exist.
 	fn load_state_snapshot(&self, path: &Path) -> Result<Vec<KeyPair>, &'static str> {
-		info!(target: LOG_TARGET, "scraping keypairs from state snapshot {:?}", path,);
+		info!(target: LOG_TARGET, "scraping key-pairs from state snapshot {:?}", path,);
 		let bytes = fs::read(path).map_err(|_| "fs::read failed.")?;
 		Decode::decode(&mut &*bytes).map_err(|_| "decode failed")
 	}
@@ -407,9 +328,9 @@ impl<B: BlockT> Builder<B> {
 			.at
 			.expect("online config must be initialized by this point; qed.")
 			.clone();
-		info!(target: LOG_TARGET, "scraping keypairs from remote @ {:?}", at);
+		info!(target: LOG_TARGET, "scraping key-pairs from remote @ {:?}", at);
 
-		let keys_and_values = if config.modules.len() > 0 {
+		let mut keys_and_values = if config.modules.len() > 0 {
 			let mut filtered_kv = vec![];
 			for f in config.modules.iter() {
 				let hashed_prefix = StorageKey(twox_128(f.as_bytes()).to_vec());
@@ -429,6 +350,12 @@ impl<B: BlockT> Builder<B> {
 			self.rpc_get_pairs_paged(StorageKey(vec![]), at).await?
 		};
 
+		for prefix in &self.hashed_prefixes {
+			info!(target: LOG_TARGET, "adding data for hashed prefix: {:?}", HexDisplay::from(prefix));
+			let additional_key_values = self.rpc_get_pairs_paged(StorageKey(prefix.to_vec()), at).await?;
+			keys_and_values.extend(additional_key_values);
+		}
+
 		Ok(keys_and_values)
 	}
 
@@ -491,6 +418,12 @@ impl<B: BlockT> Builder<B> {
 		self
 	}
 
+	/// Inject a hashed prefix. This is treated as-is, and should be pre-hashed. 
+	pub fn inject_hashed_prefix(mut self, hashed: &[u8]) -> Self {
+		self.hashed_prefixes.push(hashed.to_vec());
+		self
+	}
+
 	/// Configure a state snapshot to be used.
 	pub fn mode(mut self, mode: Mode<B>) -> Self {
 		self.mode = mode;