rework as associated type

frame/aura/src/lib.rs

@@ -81,6 +81,20 @@ pub mod pallet {
 		/// Blocks authored by a disabled validator will lead to a panic as part of this module's
 		/// initialization.
 		type DisabledValidators: DisabledValidators;
+
+		/// Whether to allow block authors to create multiple blocks per slot.
+		///
+		/// If this is `true`, the pallet will allow slots to stay the same across sequential blocks.
+		/// If this is `false`, the pallet will require that subsequent blocks always have higher slots
+		/// than previous ones.
+		///
+		/// Regardless of the setting of this storage value, the pallet will always enforce the
+		/// invariant that slots don't move backwards as the chain progresses.
+		///
+		/// The typical value for this should be 'false' unless this pallet is being augmented by
+		/// another pallet which enforces some limitation on the number of blocks authors can create
+		/// using the same slot.
+		type AllowMultipleBlocksPerSlot: Get<bool>;
 	}
 
 	#[pallet::pallet]
@@ -92,7 +106,7 @@ pub mod pallet {
 			if let Some(new_slot) = Self::current_slot_from_digests() {
 				let current_slot = CurrentSlot::<T>::get();
 
-				if AllowMultipleBlocksPerSlot::<T>::get() {
+				if T::AllowMultipleBlocksPerSlot::get() {
 					assert!(current_slot <= new_slot, "Slot must not decrease");
 				} else {
 					assert!(current_slot < new_slot, "Slot must increase");
@@ -133,22 +147,6 @@ pub mod pallet {
 	#[pallet::getter(fn current_slot)]
 	pub(super) type CurrentSlot<T: Config> = StorageValue<_, Slot, ValueQuery>;
 
-	/// Whether to allow authors to create multiple blocks per slot.
-	///
-	/// If this is `true`, the pallet will allow slots to stay the same across sequential blocks.
-	/// If this is `false`, the pallet will require that subsequent blocks always have higher slots
-	/// than previous ones.
-	///
-	/// Regardless of the setting of this storage value, the pallet will always enforce the
-	/// invariant that slots don't move backwards as the chain progresses.
-	///
-	/// The typical value for this should be 'false' unless this pallet is being augmented by
-	/// another pallet which enforces some limitation on the number of blocks authors can create
-	/// using the same slot.
-	#[pallet::storage]
-	#[pallet::getter(fn allow_multiple_blocks)]
-	pub(super) type AllowMultipleBlocksPerSlot<T: Config> = StorageValue<_, bool, ValueQuery>;
-
 	#[pallet::genesis_config]
 	#[derive(frame_support::DefaultNoBound)]
 	pub struct GenesisConfig<T: Config> {

frame/aura/src/mock.rs

@@ -82,6 +82,7 @@ impl pallet_timestamp::Config for Test {
 
 parameter_types! {
 	static DisabledValidatorTestValue: Vec<AuthorityIndex> = Default::default();
+	pub static AllowMultipleBlocksPerSlot: bool = false;
 }
 
 pub struct MockDisabledValidators;
@@ -106,6 +107,7 @@ impl pallet_aura::Config for Test {
 	type AuthorityId = AuthorityId;
 	type DisabledValidators = MockDisabledValidators;
 	type MaxAuthorities = ConstU32<10>;
+	type AllowMultipleBlocksPerSlot = AllowMultipleBlocksPerSlot;
 }
 
 pub fn new_test_ext(authorities: Vec<u64>) -> sp_io::TestExternalities {

frame/aura/src/tests.rs

@@ -19,7 +19,7 @@
 
 #![cfg(test)]
 
-use crate::mock::{new_test_ext, Aura, MockDisabledValidators, System, Test};
+use crate::mock::{new_test_ext, Aura, MockDisabledValidators, System};
 use codec::Encode;
 use frame_support::traits::OnInitialize;
 use sp_consensus_aura::{Slot, AURA_ENGINE_ID};
@@ -59,6 +59,8 @@ fn disabled_validators_cannot_author_blocks() {
 #[should_panic(expected = "Slot must increase")]
 fn pallet_requires_slot_to_increase_unless_allowed() {
 	new_test_ext(vec![0, 1, 2, 3]).execute_with(|| {
+		crate::mock::AllowMultipleBlocksPerSlot::set(false);
+
 		let slot = Slot::from(1);
 		let pre_digest =
 			Digest { logs: vec![DigestItem::PreRuntime(AURA_ENGINE_ID, slot.encode())] };
@@ -82,7 +84,7 @@ fn pallet_can_allow_unchanged_slot() {
 		System::reset_events();
 		System::initialize(&42, &System::parent_hash(), &pre_digest);
 
-		crate::AllowMultipleBlocksPerSlot::<Test>::put(true);
+		crate::mock::AllowMultipleBlocksPerSlot::set(true);
 
 		// and we should be able to initialize the block with the same slot a second time.
 		Aura::on_initialize(42);
@@ -101,7 +103,7 @@ fn pallet_always_rejects_decreasing_slot() {
 		System::reset_events();
 		System::initialize(&42, &System::parent_hash(), &pre_digest);
 
-		crate::AllowMultipleBlocksPerSlot::<Test>::put(true);
+		crate::mock::AllowMultipleBlocksPerSlot::set(true);
 
 		Aura::on_initialize(42);
 		System::finalize();