tests.rs

#[test]
fn reward_from_authorship_event_handler_works() {
	ExtBuilder::default().build_and_execute(|| {
		use pallet_authorship::EventHandler;

		assert_eq!(<pallet_authorship::Module<Test>>::author(), 11);

		<Module<Test>>::note_author(11);
		<Module<Test>>::note_uncle(21, 1);
		// Rewarding the same two times works.
		<Module<Test>>::note_uncle(11, 1);

		// Not mandatory but must be coherent with rewards
		assert_eq_uvec!(Session::validators(), vec![11, 21]);

		// 21 is rewarded as an uncle producer
		// 11 is rewarded as a block producer and uncle referencer and uncle producer
		assert_eq!(
			ErasRewardPoints::<Test>::get(Staking::active_era().unwrap().index),
			EraRewardPoints {
				individual: vec![(11, 20 + 2 * 2 + 1), (21, 1)].into_iter().collect(),
				total: 26,
			},
		);
	})
}

#[test]
fn add_reward_points_fns_works() {
	ExtBuilder::default().build_and_execute(|| {
		// Not mandatory but must be coherent with rewards
		assert_eq_uvec!(Session::validators(), vec![21, 11]);

		<Module<Test>>::reward_by_ids(vec![
			(21, 1),
			(11, 1),
			(11, 1),
		]);

		<Module<Test>>::reward_by_ids(vec![
			(21, 1),
			(11, 1),
			(11, 1),
		]);

		assert_eq!(
			ErasRewardPoints::<Test>::get(Staking::active_era().unwrap().index),
			EraRewardPoints {
				individual: vec![(11, 4), (21, 2)].into_iter().collect(),
				total: 6,
			},
		);
	})
}

#[test]
fn unbonded_balance_is_not_slashable() {
	ExtBuilder::default().build_and_execute(|| {
		// total amount staked is slashable.
		assert_eq!(Staking::slashable_balance_of(&11), 1000);

		assert_ok!(Staking::unbond(Origin::signed(10),  800));

		// only the active portion.
		assert_eq!(Staking::slashable_balance_of(&11), 200);
	})
}

#[test]
fn era_is_always_same_length() {
	// This ensures that the sessions is always of the same length if there is no forcing no
	// session changes.
	ExtBuilder::default().build_and_execute(|| {
		let session_per_era = <SessionsPerEra as Get<SessionIndex>>::get();

		mock::start_active_era(1);
		assert_eq!(Staking::eras_start_session_index(current_era()).unwrap(), session_per_era);

		mock::start_active_era(2);
		assert_eq!(Staking::eras_start_session_index(current_era()).unwrap(), session_per_era * 2u32);

		let session = Session::current_index();
		ForceEra::put(Forcing::ForceNew);
		advance_session();
		advance_session();
		assert_eq!(current_era(), 3);
		assert_eq!(Staking::eras_start_session_index(current_era()).unwrap(), session + 2);

		mock::start_active_era(4);
		assert_eq!(Staking::eras_start_session_index(current_era()).unwrap(), session + 2u32 + session_per_era);
	});
}

#[test]
fn offence_forces_new_era() {
	ExtBuilder::default().build_and_execute(|| {
		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(5)],
		);

		assert_eq!(Staking::force_era(), Forcing::ForceNew);
	});
}

#[test]
fn offence_ensures_new_era_without_clobbering() {
	ExtBuilder::default().build_and_execute(|| {
		assert_ok!(Staking::force_new_era_always(Origin::root()));
		assert_eq!(Staking::force_era(), Forcing::ForceAlways);

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(5)],
		);

		assert_eq!(Staking::force_era(), Forcing::ForceAlways);
	});
}

#[test]
fn offence_deselects_validator_even_when_slash_is_zero() {
	ExtBuilder::default().build_and_execute(|| {
		assert!(Session::validators().contains(&11));
		assert!(<Validators<Test>>::contains_key(11));

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(0)],
		);

		assert_eq!(Staking::force_era(), Forcing::ForceNew);
		assert!(!<Validators<Test>>::contains_key(11));

		mock::start_active_era(1);

		assert!(!Session::validators().contains(&11));
		assert!(!<Validators<Test>>::contains_key(11));
	});
}

#[test]
fn slashing_performed_according_exposure() {
	// This test checks that slashing is performed according the exposure (or more precisely,
	// historical exposure), not the current balance.
	ExtBuilder::default().build_and_execute(|| {
		assert_eq!(Staking::eras_stakers(Staking::active_era().unwrap().index, 11).own, 1000);

		// Handle an offence with a historical exposure.
		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Exposure {
						total: 500,
						own: 500,
						others: vec![],
					},
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(50)],
		);

		// The stash account should be slashed for 250 (50% of 500).
		assert_eq!(Balances::free_balance(11), 1000 - 250);
	});
}

#[test]
fn slash_in_old_span_does_not_deselect() {
	ExtBuilder::default().build_and_execute(|| {
		mock::start_active_era(1);

		assert!(<Validators<Test>>::contains_key(11));
		assert!(Session::validators().contains(&11));

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(0)],
		);

		assert_eq!(Staking::force_era(), Forcing::ForceNew);
		assert!(!<Validators<Test>>::contains_key(11));

		mock::start_active_era(2);

		Staking::validate(Origin::signed(10), Default::default()).unwrap();
		assert_eq!(Staking::force_era(), Forcing::NotForcing);
		assert!(<Validators<Test>>::contains_key(11));
		assert!(!Session::validators().contains(&11));

		mock::start_active_era(3);

		// this staker is in a new slashing span now, having re-registered after
		// their prior slash.

		on_offence_in_era(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(0)],
			1,
		);

		// not forcing for zero-slash and previous span.
		assert_eq!(Staking::force_era(), Forcing::NotForcing);
		assert!(<Validators<Test>>::contains_key(11));
		assert!(Session::validators().contains(&11));

		on_offence_in_era(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![],
			}],
			// NOTE: A 100% slash here would clean up the account, causing de-registration.
			&[Perbill::from_percent(95)],
			1,
		);

		// or non-zero.
		assert_eq!(Staking::force_era(), Forcing::NotForcing);
		assert!(<Validators<Test>>::contains_key(11));
		assert!(Session::validators().contains(&11));
	});
}

#[test]
fn reporters_receive_their_slice() {
	// This test verifies that the reporters of the offence receive their slice from the slashed
	// amount.
	ExtBuilder::default().build_and_execute(|| {
		// The reporters' reward is calculated from the total exposure.
		let initial_balance = 1125;

		assert_eq!(Staking::eras_stakers(Staking::active_era().unwrap().index, 11).total, initial_balance);

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![1, 2],
			}],
			&[Perbill::from_percent(50)],
		);

		// F1 * (reward_proportion * slash - 0)
		// 50% * (10% * initial_balance / 2)
		let reward = (initial_balance / 20) / 2;
		let reward_each = reward / 2; // split into two pieces.
		assert_eq!(Balances::free_balance(1), 10 + reward_each);
		assert_eq!(Balances::free_balance(2), 20 + reward_each);
	});
}

#[test]
fn subsequent_reports_in_same_span_pay_out_less() {
	// This test verifies that the reporters of the offence receive their slice from the slashed
	// amount, but less and less if they submit multiple reports in one span.
	ExtBuilder::default().build_and_execute(|| {
		// The reporters' reward is calculated from the total exposure.
		let initial_balance = 1125;

		assert_eq!(Staking::eras_stakers(Staking::active_era().unwrap().index, 11).total, initial_balance);

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![1],
			}],
			&[Perbill::from_percent(20)],
		);

		// F1 * (reward_proportion * slash - 0)
		// 50% * (10% * initial_balance * 20%)
		let reward = (initial_balance / 5) / 20;
		assert_eq!(Balances::free_balance(1), 10 + reward);

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![1],
			}],
			&[Perbill::from_percent(50)],
		);

		let prior_payout = reward;

		// F1 * (reward_proportion * slash - prior_payout)
		// 50% * (10% * (initial_balance / 2) - prior_payout)
		let reward = ((initial_balance / 20) - prior_payout) / 2;
		assert_eq!(Balances::free_balance(1), 10 + prior_payout + reward);
	});
}

#[test]
fn invulnerables_are_not_slashed() {
	// For invulnerable validators no slashing is performed.
	ExtBuilder::default().invulnerables(vec![11]).build_and_execute(|| {
		assert_eq!(Balances::free_balance(11), 1000);
		assert_eq!(Balances::free_balance(21), 2000);

		let exposure = Staking::eras_stakers(Staking::active_era().unwrap().index, 21);
		let initial_balance = Staking::slashable_balance_of(&21);

		let nominator_balances: Vec<_> = exposure.others
			.iter().map(|o| Balances::free_balance(&o.who)).collect();

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
				OffenceDetails {
					offender: (21, Staking::eras_stakers(Staking::active_era().unwrap().index, 21)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(50), Perbill::from_percent(20)],
		);

		// The validator 11 hasn't been slashed, but 21 has been.
		assert_eq!(Balances::free_balance(11), 1000);
		// 2000 - (0.2 * initial_balance)
		assert_eq!(Balances::free_balance(21), 2000 - (2 * initial_balance / 10));

		// ensure that nominators were slashed as well.
		for (initial_balance, other) in nominator_balances.into_iter().zip(exposure.others) {
			assert_eq!(
				Balances::free_balance(&other.who),
				initial_balance - (2 * other.value / 10),
			);
		}
	});
}

#[test]
fn dont_slash_if_fraction_is_zero() {
	// Don't slash if the fraction is zero.
	ExtBuilder::default().build_and_execute(|| {
		assert_eq!(Balances::free_balance(11), 1000);

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::eras_stakers(Staking::active_era().unwrap().index, 11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(0)],
		);

		// The validator hasn't been slashed. The new era is not forced.
		assert_eq!(Balances::free_balance(11), 1000);
		assert_eq!(Staking::force_era(), Forcing::ForceNew);
	});
}

#[test]
fn only_slash_for_max_in_era() {
	// multiple slashes within one era are only applied if it is more than any previous slash in the
	// same era.
	ExtBuilder::default().build_and_execute(|| {
		assert_eq!(Balances::free_balance(11), 1000);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(50)],
		);

		// The validator has been slashed and has been force-chilled.
		assert_eq!(Balances::free_balance(11), 500);
		assert_eq!(Staking::force_era(), Forcing::ForceNew);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(25)],
		);

		// The validator has not been slashed additionally.
		assert_eq!(Balances::free_balance(11), 500);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(60)],
		);

		// The validator got slashed 10% more.
		assert_eq!(Balances::free_balance(11), 400);
	})
}

#[test]
fn garbage_collection_after_slashing() {
	// ensures that `SlashingSpans` and `SpanSlash` of an account is removed after reaping.
	ExtBuilder::default().existential_deposit(2).build_and_execute(|| {
		assert_eq!(Balances::free_balance(11), 256_000);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
		);

		assert_eq!(Balances::free_balance(11), 256_000 - 25_600);
		assert!(<Staking as crate::Store>::SlashingSpans::get(&11).is_some());
		assert_eq!(<Staking as crate::Store>::SpanSlash::get(&(11, 0)).amount_slashed(), &25_600);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(100)],
		);

		// validator and nominator slash in era are garbage-collected by era change,
		// so we don't test those here.

		assert_eq!(Balances::free_balance(11), 2);
		assert_eq!(Balances::total_balance(&11), 2);

		let slashing_spans = <Staking as crate::Store>::SlashingSpans::get(&11).unwrap();
		assert_eq!(slashing_spans.iter().count(), 2);

		// reap_stash respects num_slashing_spans so that weight is accurate
		assert_noop!(Staking::reap_stash(Origin::none(), 11, 0), Error::<Test>::IncorrectSlashingSpans);
		assert_ok!(Staking::reap_stash(Origin::none(), 11, 2));

		assert!(<Staking as crate::Store>::SlashingSpans::get(&11).is_none());
		assert_eq!(<Staking as crate::Store>::SpanSlash::get(&(11, 0)).amount_slashed(), &0);
	})
}

#[test]
fn garbage_collection_on_window_pruning() {
	// ensures that `ValidatorSlashInEra` and `NominatorSlashInEra` are cleared after
	// `BondingDuration`.
	ExtBuilder::default().build_and_execute(|| {
		mock::start_active_era(1);

		assert_eq!(Balances::free_balance(11), 1000);
		let now = Staking::active_era().unwrap().index;

		let exposure = Staking::eras_stakers(now, 11);
		assert_eq!(Balances::free_balance(101), 2000);
		let nominated_value = exposure.others.iter().find(|o| o.who == 101).unwrap().value;

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(now, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
		);

		assert_eq!(Balances::free_balance(11), 900);
		assert_eq!(Balances::free_balance(101), 2000 - (nominated_value / 10));

		assert!(<Staking as crate::Store>::ValidatorSlashInEra::get(&now, &11).is_some());
		assert!(<Staking as crate::Store>::NominatorSlashInEra::get(&now, &101).is_some());

		// + 1 because we have to exit the bonding window.
		for era in (0..(BondingDuration::get() + 1)).map(|offset| offset + now + 1) {
			assert!(<Staking as crate::Store>::ValidatorSlashInEra::get(&now, &11).is_some());
			assert!(<Staking as crate::Store>::NominatorSlashInEra::get(&now, &101).is_some());

			mock::start_active_era(era);
		}

		assert!(<Staking as crate::Store>::ValidatorSlashInEra::get(&now, &11).is_none());
		assert!(<Staking as crate::Store>::NominatorSlashInEra::get(&now, &101).is_none());
	})
}

#[test]
fn slashing_nominators_by_span_max() {
	ExtBuilder::default().build_and_execute(|| {
		mock::start_active_era(1);
		mock::start_active_era(2);
		mock::start_active_era(3);

		assert_eq!(Balances::free_balance(11), 1000);
		assert_eq!(Balances::free_balance(21), 2000);
		assert_eq!(Balances::free_balance(101), 2000);
		assert_eq!(Staking::slashable_balance_of(&21), 1000);

		let exposure_11 = Staking::eras_stakers(Staking::active_era().unwrap().index, 11);
		let exposure_21 = Staking::eras_stakers(Staking::active_era().unwrap().index, 21);
		let nominated_value_11 = exposure_11.others.iter().find(|o| o.who == 101).unwrap().value;
		let nominated_value_21 = exposure_21.others.iter().find(|o| o.who == 101).unwrap().value;

		on_offence_in_era(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
			2,
		);

		assert_eq!(Balances::free_balance(11), 900);

		let slash_1_amount = Perbill::from_percent(10) * nominated_value_11;
		assert_eq!(Balances::free_balance(101), 2000 - slash_1_amount);

		let expected_spans = vec![
			slashing::SlashingSpan { index: 1, start: 4, length: None },
			slashing::SlashingSpan { index: 0, start: 0, length: Some(4) },
		];

		let get_span = |account| <Staking as crate::Store>::SlashingSpans::get(&account).unwrap();

		assert_eq!(
			get_span(11).iter().collect::<Vec<_>>(),
			expected_spans,
		);

		assert_eq!(
			get_span(101).iter().collect::<Vec<_>>(),
			expected_spans,
		);

		// second slash: higher era, higher value, same span.
		on_offence_in_era(
			&[
				OffenceDetails {
					offender: (21, Staking::eras_stakers(Staking::active_era().unwrap().index, 21)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(30)],
			3,
		);

		// 11 was not further slashed, but 21 and 101 were.
		assert_eq!(Balances::free_balance(11), 900);
		assert_eq!(Balances::free_balance(21), 1700);

		let slash_2_amount = Perbill::from_percent(30) * nominated_value_21;
		assert!(slash_2_amount > slash_1_amount);

		// only the maximum slash in a single span is taken.
		assert_eq!(Balances::free_balance(101), 2000 - slash_2_amount);

		// third slash: in same era and on same validator as first, higher
		// in-era value, but lower slash value than slash 2.
		on_offence_in_era(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(20)],
			2,
		);

		// 11 was further slashed, but 21 and 101 were not.
		assert_eq!(Balances::free_balance(11), 800);
		assert_eq!(Balances::free_balance(21), 1700);

		let slash_3_amount = Perbill::from_percent(20) * nominated_value_21;
		assert!(slash_3_amount < slash_2_amount);
		assert!(slash_3_amount > slash_1_amount);

		// only the maximum slash in a single span is taken.
		assert_eq!(Balances::free_balance(101), 2000 - slash_2_amount);
	});
}

#[test]
fn slashes_are_summed_across_spans() {
	ExtBuilder::default().build_and_execute(|| {
		mock::start_active_era(1);
		mock::start_active_era(2);
		mock::start_active_era(3);

		assert_eq!(Balances::free_balance(21), 2000);
		assert_eq!(Staking::slashable_balance_of(&21), 1000);

		let get_span = |account| <Staking as crate::Store>::SlashingSpans::get(&account).unwrap();

		on_offence_now(
			&[
				OffenceDetails {
					offender: (21, Staking::eras_stakers(Staking::active_era().unwrap().index, 21)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
		);

		let expected_spans = vec![
			slashing::SlashingSpan { index: 1, start: 4, length: None },
			slashing::SlashingSpan { index: 0, start: 0, length: Some(4) },
		];

		assert_eq!(get_span(21).iter().collect::<Vec<_>>(), expected_spans);
		assert_eq!(Balances::free_balance(21), 1900);

		// 21 has been force-chilled. re-signal intent to validate.
		Staking::validate(Origin::signed(20), Default::default()).unwrap();

		mock::start_active_era(4);

		assert_eq!(Staking::slashable_balance_of(&21), 900);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (21, Staking::eras_stakers(Staking::active_era().unwrap().index, 21)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
		);

		let expected_spans = vec![
			slashing::SlashingSpan { index: 2, start: 5, length: None },
			slashing::SlashingSpan { index: 1, start: 4, length: Some(1) },
			slashing::SlashingSpan { index: 0, start: 0, length: Some(4) },
		];

		assert_eq!(get_span(21).iter().collect::<Vec<_>>(), expected_spans);
		assert_eq!(Balances::free_balance(21), 1810);
	});
}

#[test]
fn deferred_slashes_are_deferred() {
	ExtBuilder::default()
		.slash_defer_duration(2)
		.build_and_execute(|| {
			mock::start_active_era(1);

			assert_eq!(Balances::free_balance(11), 1000);

			let exposure = Staking::eras_stakers(Staking::active_era().unwrap().index, 11);
			assert_eq!(Balances::free_balance(101), 2000);
			let nominated_value = exposure.others.iter().find(|o| o.who == 101).unwrap().value;

			on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::eras_stakers(Staking::active_era().unwrap().index, 11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
		);

			assert_eq!(Balances::free_balance(11), 1000);
			assert_eq!(Balances::free_balance(101), 2000);

			mock::start_active_era(2);

			assert_eq!(Balances::free_balance(11), 1000);
			assert_eq!(Balances::free_balance(101), 2000);

			mock::start_active_era(3);

			assert_eq!(Balances::free_balance(11), 1000);
			assert_eq!(Balances::free_balance(101), 2000);

			// at the start of era 4, slashes from era 1 are processed,
			// after being deferred for at least 2 full eras.
			mock::start_active_era(4);

			assert_eq!(Balances::free_balance(11), 900);
			assert_eq!(Balances::free_balance(101), 2000 - (nominated_value / 10));
		})
}

#[test]
fn remove_deferred() {
	ExtBuilder::default()
		.slash_defer_duration(2)
		.build_and_execute(|| {
			mock::start_active_era(1);

			assert_eq!(Balances::free_balance(11), 1000);

			let exposure = Staking::eras_stakers(Staking::active_era().unwrap().index, 11);
			assert_eq!(Balances::free_balance(101), 2000);
			let nominated_value = exposure.others.iter().find(|o| o.who == 101).unwrap().value;

			on_offence_now(
			&[
				OffenceDetails {
					offender: (11, exposure.clone()),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
		);

			assert_eq!(Balances::free_balance(11), 1000);
			assert_eq!(Balances::free_balance(101), 2000);

			mock::start_active_era(2);

			on_offence_in_era(
			&[
				OffenceDetails {
					offender: (11, exposure.clone()),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(15)],
			1,
		);

		// fails if empty
		assert_noop!(
			Staking::cancel_deferred_slash(Origin::root(), 1, vec![]),
			Error::<Test>::EmptyTargets
		);

			assert_ok!(Staking::cancel_deferred_slash(Origin::root(), 1, vec![0]));

			assert_eq!(Balances::free_balance(11), 1000);
			assert_eq!(Balances::free_balance(101), 2000);

			mock::start_active_era(3);

			assert_eq!(Balances::free_balance(11), 1000);
			assert_eq!(Balances::free_balance(101), 2000);

			// at the start of era 4, slashes from era 1 are processed,
			// after being deferred for at least 2 full eras.
			mock::start_active_era(4);

			// the first slash for 10% was cancelled, so no effect.
			assert_eq!(Balances::free_balance(11), 1000);
			assert_eq!(Balances::free_balance(101), 2000);

			mock::start_active_era(5);

			let slash_10 = Perbill::from_percent(10);
			let slash_15 = Perbill::from_percent(15);
			let initial_slash = slash_10 * nominated_value;

			let total_slash = slash_15 * nominated_value;
			let actual_slash = total_slash - initial_slash;

		// 5% slash (15 - 10) processed now.
		assert_eq!(Balances::free_balance(11), 950);
		assert_eq!(Balances::free_balance(101), 2000 - actual_slash);
	})
}

#[test]
fn remove_multi_deferred() {
	ExtBuilder::default()
		.slash_defer_duration(2)
		.build_and_execute(|| {
			mock::start_active_era(1);

			assert_eq!(Balances::free_balance(11), 1000);

			let exposure = Staking::eras_stakers(Staking::active_era().unwrap().index, 11);
			assert_eq!(Balances::free_balance(101), 2000);

			on_offence_now(
			&[
				OffenceDetails {
					offender: (11, exposure.clone()),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(10)],
		);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (21, Staking::eras_stakers(Staking::active_era().unwrap().index, 21)),
					reporters: vec![],
				}
			],
			&[Perbill::from_percent(10)],
		);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, exposure.clone()),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(25)],
		);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (42, exposure.clone()),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(25)],
		);

		on_offence_now(
			&[
				OffenceDetails {
					offender: (69, exposure.clone()),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(25)],
		);

		assert_eq!(<Staking as Store>::UnappliedSlashes::get(&1).len(), 5);

		// fails if list is not sorted
		assert_noop!(
			Staking::cancel_deferred_slash(Origin::root(), 1, vec![2, 0, 4]),
			Error::<Test>::NotSortedAndUnique
		);
		// fails if list is not unique
		assert_noop!(
			Staking::cancel_deferred_slash(Origin::root(), 1, vec![0, 2, 2]),
			Error::<Test>::NotSortedAndUnique
		);
		// fails if bad index
		assert_noop!(
			Staking::cancel_deferred_slash(Origin::root(), 1, vec![1, 2, 3, 4, 5]),
			Error::<Test>::InvalidSlashIndex
		);

		assert_ok!(Staking::cancel_deferred_slash(Origin::root(), 1, vec![0, 2, 4]));

		let slashes = <Staking as Store>::UnappliedSlashes::get(&1);
		assert_eq!(slashes.len(), 2);
		assert_eq!(slashes[0].validator, 21);
		assert_eq!(slashes[1].validator, 42);
	})
}

mod offchain_election {
	use crate::*;
	use codec::Encode;
	use frame_support::{
		assert_noop, assert_ok, assert_err_with_weight,
		dispatch::DispatchResultWithPostInfo,
	};
	use sp_runtime::transaction_validity::TransactionSource;
	use mock::*;
	use parking_lot::RwLock;
	use sp_core::offchain::{
		testing::{PoolState, TestOffchainExt, TestTransactionPoolExt},
		OffchainWorkerExt, TransactionPoolExt, OffchainDbExt,
	};
	use sp_io::TestExternalities;
	use sp_npos_elections::StakedAssignment;
	use frame_support::traits::OffchainWorker;
	use std::sync::Arc;
	use substrate_test_utils::assert_eq_uvec;

	fn percent(x: u16) -> OffchainAccuracy {
		OffchainAccuracy::from_percent(x)
	}

	/// setup a new set of validators and nominator storage items independent of the parent mock
	/// file. This produces a edge graph that can be reduced.
	pub fn build_offchain_election_test_ext() {
		for i in (10..=40).step_by(10) {
			// Note: we respect the convention of the mock (10, 11 pairs etc.) since these accounts
			// have corresponding keys in session which makes everything more ergonomic and
			// realistic.
			bond_validator(i + 1, i, 100);
		}

		let mut voter = 1;
		bond_nominator(voter, 1000 + voter, 100, vec![11]);
		voter = 2;
		bond_nominator(voter, 1000 + voter, 100, vec![11, 11]);
		voter = 3;
		bond_nominator(voter, 1000 + voter, 100, vec![21, 41]);
		voter = 4;
		bond_nominator(voter, 1000 + voter, 100, vec![21, 31, 41]);
		voter = 5;
		bond_nominator(voter, 1000 + voter, 100, vec![21, 31, 41]);
	}

	/// convert an externalities to one that can handle offchain worker tests.
	fn offchainify(ext: &mut TestExternalities, iterations: u32) -> Arc<RwLock<PoolState>> {
		let (offchain, offchain_state) = TestOffchainExt::new();
		let (pool, pool_state) = TestTransactionPoolExt::new();

		let mut seed = [0_u8; 32];
		seed[0..4].copy_from_slice(&iterations.to_le_bytes());
		offchain_state.write().seed = seed;

		ext.register_extension(OffchainDbExt::new(offchain.clone()));
		ext.register_extension(OffchainWorkerExt::new(offchain));
		ext.register_extension(TransactionPoolExt::new(pool));

		pool_state
	}

	fn election_size() -> ElectionSize {
		ElectionSize {
			validators: Staking::snapshot_validators().unwrap().len() as ValidatorIndex,
			nominators: Staking::snapshot_nominators().unwrap().len() as NominatorIndex,
		}
	}

	fn submit_solution(
		origin: Origin,
		winners: Vec<ValidatorIndex>,
		compact: CompactAssignments,
		score: ElectionScore,
	) -> DispatchResultWithPostInfo {
		Staking::submit_election_solution(
			origin,
			winners,
			compact,
			score,
			current_era(),
			election_size(),
		)
	}

	#[test]
	fn is_current_session_final_works() {
		ExtBuilder::default()
			.session_per_era(3)
			.build()
			.execute_with(|| {
				mock::start_active_era(1);
				assert_eq!(Session::current_index(), 3);