Introduce srml/scored-pool (#3381)

* Introduce srml/scored-pool

* Bump impl_version

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Remove unnecessary pub use

* Remove unnecessary import

* Adapt to InitializeMembers

* Bump impl_version

* Implement remarks (shortens code)

* Improve complexity of score()

Search and remove and search again for the
new spot and insert then => O(2LogN).

* Get rid of a clone()

* Reduce complexity of issue_candidacy()

* Add CandidateScored event + Improve comments

* Fix naming

* Use Lookup instead of AccountId as param

* Use set_members_sorted instead of computing diff

* Remove function which is only used during genesis

* Get rid of rev() by changing sort order of Pool

* Rename issue_candidacy to submit_candidacy

* Shorten code

* Remove find_in_pool() and have transactor submit index

* Remove unnecessary dependency

* Improve error messages

* Improve naming

* Improve comments

* Make code clearer wrt which receiver to invoke

* Adapt to new system trait

* Refactor to request CandidateDeposit only once

* Refactor to request Pool only once

* Improve structure and comments

substrate/srml/scored-pool/src/mock.rs

@@ -0,0 +1,177 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Test utilities
+
+use super::*;
+
+use std::cell::RefCell;
+use srml_support::{impl_outer_origin, parameter_types};
+use primitives::{H256, Blake2Hasher};
+// The testing primitives are very useful for avoiding having to work with signatures
+// or public keys. `u64` is used as the `AccountId` and no `Signature`s are requried.
+use sr_primitives::{
+	Perbill, traits::{BlakeTwo256, IdentityLookup}, testing::Header,
+};
+use system::EnsureSignedBy;
+
+impl_outer_origin! {
+	pub enum Origin for Test {}
+}
+
+// For testing the module, we construct most of a mock runtime. This means
+// first constructing a configuration type (`Test`) which `impl`s each of the
+// configuration traits of modules we want to use.
+#[derive(Clone, Eq, PartialEq)]
+pub struct Test;
+parameter_types! {
+	pub const CandidateDeposit: u64 = 25;
+	pub const Period: u64 = 4;
+
+	pub const KickOrigin: u64 = 2;
+	pub const ScoreOrigin: u64 = 3;
+
+	pub const BlockHashCount: u64 = 250;
+	pub const MaximumBlockWeight: u32 = 1024;
+	pub const MaximumBlockLength: u32 = 2 * 1024;
+	pub const AvailableBlockRatio: Perbill = Perbill::one();
+
+	pub const ExistentialDeposit: u64 = 0;
+	pub const TransferFee: u64 = 0;
+	pub const CreationFee: u64 = 0;
+	pub const TransactionBaseFee: u64 = 0;
+	pub const TransactionByteFee: u64 = 0;
+}
+
+impl system::Trait for Test {
+	type Origin = Origin;
+	type Index = u64;
+	type BlockNumber = u64;
+	type Hash = H256;
+	type Call = ();
+	type Hashing = BlakeTwo256;
+	type AccountId = u64;
+	type Lookup = IdentityLookup<Self::AccountId>;
+	type Header = Header;
+	type WeightMultiplierUpdate = ();
+	type Event = ();
+	type BlockHashCount = BlockHashCount;
+	type MaximumBlockWeight = MaximumBlockWeight;
+	type MaximumBlockLength = MaximumBlockLength;
+	type AvailableBlockRatio = AvailableBlockRatio;
+	type Version = ();
+}
+
+impl balances::Trait for Test {
+	type Balance = u64;
+	type OnFreeBalanceZero = ();
+	type OnNewAccount = ();
+	type Event = ();
+	type TransactionPayment = ();
+	type TransferPayment = ();
+	type DustRemoval = ();
+	type ExistentialDeposit = ExistentialDeposit;
+	type TransferFee = TransferFee;
+	type CreationFee = CreationFee;
+	type TransactionBaseFee = TransactionBaseFee;
+	type TransactionByteFee = TransactionByteFee;
+	type WeightToFee = ();
+}
+
+thread_local! {
+	pub static MEMBERS: RefCell<Vec<u64>> = RefCell::new(vec![]);
+}
+
+pub struct TestChangeMembers;
+impl ChangeMembers<u64> for TestChangeMembers {
+	fn change_members_sorted(incoming: &[u64], outgoing: &[u64], new: &[u64]) {
+		let mut old_plus_incoming = MEMBERS.with(|m| m.borrow().to_vec());
+		old_plus_incoming.extend_from_slice(incoming);
+		old_plus_incoming.sort();
+
+		let mut new_plus_outgoing = new.to_vec();
+		new_plus_outgoing.extend_from_slice(outgoing);
+		new_plus_outgoing.sort();
+
+		assert_eq!(old_plus_incoming, new_plus_outgoing);
+
+		MEMBERS.with(|m| *m.borrow_mut() = new.to_vec());
+	}
+}
+
+impl InitializeMembers<u64> for TestChangeMembers {
+	fn initialize_members(new_members: &[u64]) {
+		MEMBERS.with(|m| *m.borrow_mut() = new_members.to_vec());
+	}
+}
+
+impl Trait for Test {
+	type Event = ();
+	type KickOrigin = EnsureSignedBy<KickOrigin, u64>;
+	type MembershipInitialized = TestChangeMembers;
+	type MembershipChanged = TestChangeMembers;
+	type Currency = balances::Module<Self>;
+	type CandidateDeposit = CandidateDeposit;
+	type Period = Period;
+	type Score = u64;
+	type ScoreOrigin = EnsureSignedBy<ScoreOrigin, u64>;
+}
+
+// This function basically just builds a genesis storage key/value store according to
+// our desired mockup.
+pub fn new_test_ext() -> sr_io::TestExternalities<Blake2Hasher> {
+	let mut t = system::GenesisConfig::default().build_storage::<Test>().unwrap();
+	// We use default for brevity, but you can configure as desired if needed.
+	balances::GenesisConfig::<Test> {
+		balances: vec![
+			(5, 500_000),
+			(10, 500_000),
+			(15, 500_000),
+			(20, 500_000),
+			(31, 500_000),
+			(40, 500_000),
+			(99, 1),
+		],
+		vesting: vec![],
+	}.assimilate_storage(&mut t).unwrap();
+	GenesisConfig::<Test>{
+		pool: vec![
+			(5, None),
+			(10, Some(1)),
+			(20, Some(2)),
+			(31, Some(2)),
+			(40, Some(3)),
+		],
+		member_count: 2,
+		.. Default::default()
+	}.assimilate_storage(&mut t).unwrap();
+	t.into()
+}
+
+/// Fetch an entity from the pool, if existent.
+pub fn fetch_from_pool(who: u64) -> Option<(u64, Option<u64>)> {
+	<Module<Test>>::pool()
+		.into_iter()
+		.find(|item| item.0 == who)
+}
+
+/// Find an entity in the pool.
+/// Returns its position in the `Pool` vec, if existent.
+pub fn find_in_pool(who: u64) -> Option<usize> {
+	<Module<Test>>::pool()
+		.into_iter()
+		.position(|item| item.0 == who)
+}