[author-slot-filter] Add using_fake_author logic

pallets/author-slot-filter/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 version = "0.9.0"
 
 [dependencies]
+environmental = { workspace = true }
 frame-support = { workspace = true }
 frame-system = { workspace = true }
 log = { workspace = true }

pallets/author-slot-filter/src/lib.rs

@@ -48,14 +48,23 @@ pub mod pallet {
 	use super::*;
 	use crate::num::NonZeroU32;
 	use crate::weights::WeightInfo;
-	use frame_support::{pallet_prelude::*, traits::Randomness};
+	use frame_support::{pallet_prelude::*, storage::unhashed, traits::Randomness};
 	use frame_system::pallet_prelude::*;
 	use log::debug;
 	use nimbus_primitives::CanAuthor;
 	use sp_core::H256;
 	use sp_runtime::Percent;
 	use sp_std::vec::Vec;
 
+	/// Storage key to be used for fake author logic
+	const IS_FAKE_AUTHOR_KEY: &[u8] = b"AuthorSlotFilter:IsFakeAuthor";
+
+	environmental::environmental!(IS_FAKE_AUTHOR: ());
+	/// Use fake author logic
+	pub fn using_fake_author<R, F: FnOnce() -> R>(mutator: F) -> R {
+		IS_FAKE_AUTHOR::using(&mut (), mutator)
+	}
+
 	/// The Author Filter pallet
 	#[pallet::pallet]
 	#[pallet::without_storage_info]
@@ -76,6 +85,16 @@ pub mod pallet {
 		type WeightInfo: WeightInfo;
 	}
 
+	#[pallet::hooks]
+	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
+		fn on_initialize(_now: BlockNumberFor<T>) -> Weight {
+			if IS_FAKE_AUTHOR::with(|_| ()).is_some() {
+				unhashed::put(IS_FAKE_AUTHOR_KEY, &());
+			}
+			T::DbWeight::get().reads_writes(0, 1)
+		}
+	}
+
 	/// Compute a pseudo-random subset of the input accounts by using Pallet's
 	/// source of randomness, `Config::RandomnessSource`.
 	/// Returns (Eligible, Ineligible), each is a set of accounts
@@ -127,6 +146,11 @@ pub mod pallet {
 	impl<T: Config> CanAuthor<T::AccountId> for Pallet<T> {
 		#[cfg(not(feature = "try-runtime"))]
 		fn can_author(author: &T::AccountId, slot: &u32) -> bool {
+			// Check if fake author logic is being used
+			if unhashed::get::<()>(IS_FAKE_AUTHOR_KEY).is_some() {
+				return true;
+			}
+
 			// Compute pseudo-random subset of potential authors
 			let (eligible, ineligible) =
 				compute_pseudo_random_subset::<T>(T::PotentialAuthors::get(), slot);

pallets/author-slot-filter/src/tests.rs

@@ -19,8 +19,9 @@ pub use crate::mock::*;
 use crate::num::NonZeroU32;
 
 use frame_support::assert_ok;
-use frame_support::traits::OnRuntimeUpgrade;
+use frame_support::traits::{OnInitialize, OnRuntimeUpgrade};
 use frame_support::weights::Weight;
+use nimbus_primitives::CanAuthor;
 use sp_runtime::Percent;
 
 #[test]
@@ -97,3 +98,13 @@ fn test_migration_inserts_default_value_for_missing_eligible_ratio() {
 		assert_eq!(expected_default_eligible_count, actual_eligible_count);
 	});
 }
+
+#[test]
+fn test_using_fake_author_works() {
+	new_test_ext().execute_with(|| {
+		using_fake_author(|| {
+			AuthorSlotFilter::on_initialize(System::block_number());
+			assert!(AuthorSlotFilter::can_author(&42, &42));
+		});
+	});
+}