Thread-local parameter_types for testing. (#7542)

* Thread-local parameter_types for testing.

* Better docs.

* Some minors

* Merge'em

* Update frame/support/src/lib.rs

Co-authored-by: Bastian Köcher <[email protected]>

* Align more to basti's trick

* Update frame/support/src/lib.rs

* Update frame/support/src/lib.rs

Co-authored-by: Bastian Köcher <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>

Author: kianenigma

src/mock.rs

@@ -47,12 +47,6 @@ pub(crate) type Balance = u128;
 
 thread_local! {
 	static SESSION: RefCell<(Vec<AccountId>, HashSet<AccountId>)> = RefCell::new(Default::default());
-	static SESSION_PER_ERA: RefCell<SessionIndex> = RefCell::new(3);
-	static EXISTENTIAL_DEPOSIT: RefCell<Balance> = RefCell::new(0);
-	static SLASH_DEFER_DURATION: RefCell<EraIndex> = RefCell::new(0);
-	static ELECTION_LOOKAHEAD: RefCell<BlockNumber> = RefCell::new(0);
-	static PERIOD: RefCell<BlockNumber> = RefCell::new(1);
-	static MAX_ITERATIONS: RefCell<u32> = RefCell::new(0);
 }
 
 /// Another session handler struct to test on_disabled.
@@ -92,53 +86,6 @@ pub fn is_disabled(controller: AccountId) -> bool {
 	SESSION.with(|d| d.borrow().1.contains(&stash))
 }
 
-pub struct ExistentialDeposit;
-impl Get<Balance> for ExistentialDeposit {
-	fn get() -> Balance {
-		EXISTENTIAL_DEPOSIT.with(|v| *v.borrow())
-	}
-}
-
-pub struct SessionsPerEra;
-impl Get<SessionIndex> for SessionsPerEra {
-	fn get() -> SessionIndex {
-		SESSION_PER_ERA.with(|v| *v.borrow())
-	}
-}
-impl Get<BlockNumber> for SessionsPerEra {
-	fn get() -> BlockNumber {
-		SESSION_PER_ERA.with(|v| *v.borrow() as BlockNumber)
-	}
-}
-
-pub struct ElectionLookahead;
-impl Get<BlockNumber> for ElectionLookahead {
-	fn get() -> BlockNumber {
-		ELECTION_LOOKAHEAD.with(|v| *v.borrow())
-	}
-}
-
-pub struct Period;
-impl Get<BlockNumber> for Period {
-	fn get() -> BlockNumber {
-		PERIOD.with(|v| *v.borrow())
-	}
-}
-
-pub struct SlashDeferDuration;
-impl Get<EraIndex> for SlashDeferDuration {
-	fn get() -> EraIndex {
-		SLASH_DEFER_DURATION.with(|v| *v.borrow())
-	}
-}
-
-pub struct MaxIterations;
-impl Get<u32> for MaxIterations {
-	fn get() -> u32 {
-		MAX_ITERATIONS.with(|v| *v.borrow())
-	}
-}
-
 impl_outer_origin! {
 	pub enum Origin for Test where system = frame_system {}
 }
@@ -186,7 +133,14 @@ parameter_types! {
 	pub const MaximumBlockLength: u32 = 2 * 1024;
 	pub const AvailableBlockRatio: Perbill = Perbill::one();
 	pub const MaxLocks: u32 = 1024;
+	pub static SessionsPerEra: SessionIndex = 3;
+	pub static ExistentialDeposit: Balance = 0;
+	pub static SlashDeferDuration: EraIndex = 0;
+	pub static ElectionLookahead: BlockNumber = 0;
+	pub static Period: BlockNumber = 1;
+	pub static MaxIterations: u32 = 0;
 }
+
 impl frame_system::Trait for Test {
 	type BaseCallFilter = ();
 	type Origin = Origin;
@@ -437,7 +391,7 @@ impl ExtBuilder {
 	pub fn set_associated_constants(&self) {
 		EXISTENTIAL_DEPOSIT.with(|v| *v.borrow_mut() = self.existential_deposit);
 		SLASH_DEFER_DURATION.with(|v| *v.borrow_mut() = self.slash_defer_duration);
-		SESSION_PER_ERA.with(|v| *v.borrow_mut() = self.session_per_era);
+		SESSIONS_PER_ERA.with(|v| *v.borrow_mut() = self.session_per_era);
 		ELECTION_LOOKAHEAD.with(|v| *v.borrow_mut() = self.election_lookahead);
 		PERIOD.with(|v| *v.borrow_mut() = self.session_length);
 		MAX_ITERATIONS.with(|v| *v.borrow_mut() = self.max_offchain_iterations);