tests.rs

		let total_payout_2 = current_total_payout_for_duration(reward_time_per_era());
		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);

		mock::start_active_era(3);
		mock::make_all_reward_payment(2);

		// Check that RewardDestination is Controller
		assert_eq!(Staking::payee(&11), RewardDestination::Controller);
		// Check that reward went to the controller account
		assert_eq!(Balances::free_balance(10), 1 + total_payout_2);
		// Check that amount at stake is NOT increased
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000 + total_payout_0,
				active: 1000 + total_payout_0,
				unlocking: vec![],
				claimed_rewards: vec![0, 1, 2],
			})
		);
		// Check that amount in staked account is NOT increased.
		assert_eq!(Balances::free_balance(11), recorded_stash_balance);
	});
}

#[test]
fn validator_payment_prefs_work() {
	// Test that validator preferences are correctly honored
	// Note: unstake threshold is being directly tested in slashing tests.
	// This test will focus on validator payment.
	ExtBuilder::default().build_and_execute(|| {
		let commission = Perbill::from_percent(40);
		<Validators<Test>>::insert(
			&11,
			ValidatorPrefs { commission: commission.clone(), ..Default::default() },
		);

		// Reward controller so staked ratio doesn't change.
		<Payee<Test>>::insert(&11, RewardDestination::Controller);
		<Payee<Test>>::insert(&101, RewardDestination::Controller);

		mock::start_active_era(1);
		mock::make_all_reward_payment(0);

		let balance_era_1_10 = Balances::total_balance(&10);
		let balance_era_1_100 = Balances::total_balance(&100);

		// Compute total payout now for whole duration as other parameter won't change
		let total_payout_1 = current_total_payout_for_duration(reward_time_per_era());
		let exposure_1 = Staking::eras_stakers(active_era(), 11);
		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);

		mock::start_active_era(2);
		mock::make_all_reward_payment(1);

		let taken_cut = commission * total_payout_1;
		let shared_cut = total_payout_1 - taken_cut;
		let reward_of_10 = shared_cut * exposure_1.own / exposure_1.total + taken_cut;
		let reward_of_100 = shared_cut * exposure_1.others[0].value / exposure_1.total;
		assert_eq_error_rate!(Balances::total_balance(&10), balance_era_1_10 + reward_of_10, 2);
		assert_eq_error_rate!(Balances::total_balance(&100), balance_era_1_100 + reward_of_100, 2);
	});
}

#[test]
fn bond_extra_works() {
	// Tests that extra `free_balance` in the stash can be added to stake
	// NOTE: this tests only verifies `StakingLedger` for correct updates
	// See `bond_extra_and_withdraw_unbonded_works` for more details and updates on `Exposure`.
	ExtBuilder::default().build_and_execute(|| {
		// Check that account 10 is a validator
		assert!(<Validators<Test>>::contains_key(11));
		// Check that account 10 is bonded to account 11
		assert_eq!(Staking::bonded(&11), Some(10));
		// Check how much is at stake
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 1000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);

		// Give account 11 some large free balance greater than total
		let _ = Balances::make_free_balance_be(&11, 1000000);

		// Call the bond_extra function from controller, add only 100
		assert_ok!(Staking::bond_extra(Origin::signed(11), 100));
		// There should be 100 more `total` and `active` in the ledger
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000 + 100,
				active: 1000 + 100,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);

		// Call the bond_extra function with a large number, should handle it
		assert_ok!(Staking::bond_extra(Origin::signed(11), Balance::max_value()));
		// The full amount of the funds should now be in the total and active
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000000,
				active: 1000000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);
	});
}

#[test]
fn bond_extra_and_withdraw_unbonded_works() {
	//
	// * Should test
	// * Given an account being bonded [and chosen as a validator](not mandatory)
	// * It can add extra funds to the bonded account.
	// * it can unbond a portion of its funds from the stash account.
	// * Once the unbonding period is done, it can actually take the funds out of the stash.
	ExtBuilder::default().nominate(false).build_and_execute(|| {
		// Set payee to controller. avoids confusion
		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));

		// Give account 11 some large free balance greater than total
		let _ = Balances::make_free_balance_be(&11, 1000000);

		// Initial config should be correct
		assert_eq!(active_era(), 0);

		// check the balance of a validator accounts.
		assert_eq!(Balances::total_balance(&10), 1);

		// confirm that 10 is a normal validator and gets paid at the end of the era.
		mock::start_active_era(1);

		// Initial state of 10
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 1000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);
		assert_eq!(
			Staking::eras_stakers(active_era(), 11),
			Exposure { total: 1000, own: 1000, others: vec![] }
		);

		// deposit the extra 100 units
		Staking::bond_extra(Origin::signed(11), 100).unwrap();

		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000 + 100,
				active: 1000 + 100,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);
		// Exposure is a snapshot! only updated after the next era update.
		assert_ne!(
			Staking::eras_stakers(active_era(), 11),
			Exposure { total: 1000 + 100, own: 1000 + 100, others: vec![] }
		);

		// trigger next era.
		mock::start_active_era(2);
		assert_eq!(active_era(), 2);

		// ledger should be the same.
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000 + 100,
				active: 1000 + 100,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);
		// Exposure is now updated.
		assert_eq!(
			Staking::eras_stakers(active_era(), 11),
			Exposure { total: 1000 + 100, own: 1000 + 100, others: vec![] }
		);

		// Unbond almost all of the funds in stash.
		Staking::unbond(Origin::signed(10), 1000).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000 + 100,
				active: 100,
				unlocking: vec![UnlockChunk { value: 1000, era: 2 + 3 }],
				claimed_rewards: vec![]
			}),
		);

		// Attempting to free the balances now will fail. 2 eras need to pass.
		assert_ok!(Staking::withdraw_unbonded(Origin::signed(10), 0));
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000 + 100,
				active: 100,
				unlocking: vec![UnlockChunk { value: 1000, era: 2 + 3 }],
				claimed_rewards: vec![]
			}),
		);

		// trigger next era.
		mock::start_active_era(3);

		// nothing yet
		assert_ok!(Staking::withdraw_unbonded(Origin::signed(10), 0));
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000 + 100,
				active: 100,
				unlocking: vec![UnlockChunk { value: 1000, era: 2 + 3 }],
				claimed_rewards: vec![]
			}),
		);

		// trigger next era.
		mock::start_active_era(5);

		assert_ok!(Staking::withdraw_unbonded(Origin::signed(10), 0));
		// Now the value is free and the staking ledger is updated.
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 100,
				active: 100,
				unlocking: vec![],
				claimed_rewards: vec![]
			}),
		);
	})
}

#[test]
fn too_many_unbond_calls_should_not_work() {
	ExtBuilder::default().build_and_execute(|| {
		// locked at era 0 until 3
		for _ in 0..MAX_UNLOCKING_CHUNKS - 1 {
			assert_ok!(Staking::unbond(Origin::signed(10), 1));
		}

		mock::start_active_era(1);

		// locked at era 1 until 4
		assert_ok!(Staking::unbond(Origin::signed(10), 1));
		// can't do more.
		assert_noop!(Staking::unbond(Origin::signed(10), 1), Error::<Test>::NoMoreChunks);

		mock::start_active_era(3);

		assert_noop!(Staking::unbond(Origin::signed(10), 1), Error::<Test>::NoMoreChunks);
		// free up.
		assert_ok!(Staking::withdraw_unbonded(Origin::signed(10), 0));

		// Can add again.
		assert_ok!(Staking::unbond(Origin::signed(10), 1));
		assert_eq!(Staking::ledger(&10).unwrap().unlocking.len(), 2);
	})
}

#[test]
fn rebond_works() {
	//
	// * Should test
	// * Given an account being bonded [and chosen as a validator](not mandatory)
	// * it can unbond a portion of its funds from the stash account.
	// * it can re-bond a portion of the funds scheduled to unlock.
	ExtBuilder::default().nominate(false).build_and_execute(|| {
		// Set payee to controller. avoids confusion
		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));

		// Give account 11 some large free balance greater than total
		let _ = Balances::make_free_balance_be(&11, 1000000);

		// confirm that 10 is a normal validator and gets paid at the end of the era.
		mock::start_active_era(1);

		// Initial state of 10
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 1000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);

		mock::start_active_era(2);
		assert_eq!(active_era(), 2);

		// Try to rebond some funds. We get an error since no fund is unbonded.
		assert_noop!(Staking::rebond(Origin::signed(10), 500), Error::<Test>::NoUnlockChunk);

		// Unbond almost all of the funds in stash.
		Staking::unbond(Origin::signed(10), 900).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 100,
				unlocking: vec![UnlockChunk { value: 900, era: 2 + 3 }],
				claimed_rewards: vec![],
			})
		);

		// Re-bond all the funds unbonded.
		Staking::rebond(Origin::signed(10), 900).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 1000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);

		// Unbond almost all of the funds in stash.
		Staking::unbond(Origin::signed(10), 900).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 100,
				unlocking: vec![UnlockChunk { value: 900, era: 5 }],
				claimed_rewards: vec![],
			})
		);

		// Re-bond part of the funds unbonded.
		Staking::rebond(Origin::signed(10), 500).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 600,
				unlocking: vec![UnlockChunk { value: 400, era: 5 }],
				claimed_rewards: vec![],
			})
		);

		// Re-bond the remainder of the funds unbonded.
		Staking::rebond(Origin::signed(10), 500).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 1000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);

		// Unbond parts of the funds in stash.
		Staking::unbond(Origin::signed(10), 300).unwrap();
		Staking::unbond(Origin::signed(10), 300).unwrap();
		Staking::unbond(Origin::signed(10), 300).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 100,
				unlocking: vec![
					UnlockChunk { value: 300, era: 5 },
					UnlockChunk { value: 300, era: 5 },
					UnlockChunk { value: 300, era: 5 },
				],
				claimed_rewards: vec![],
			})
		);

		// Re-bond part of the funds unbonded.
		Staking::rebond(Origin::signed(10), 500).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 600,
				unlocking: vec![
					UnlockChunk { value: 300, era: 5 },
					UnlockChunk { value: 100, era: 5 },
				],
				claimed_rewards: vec![],
			})
		);
	})
}

#[test]
fn rebond_is_fifo() {
	// Rebond should proceed by reversing the most recent bond operations.
	ExtBuilder::default().nominate(false).build_and_execute(|| {
		// Set payee to controller. avoids confusion
		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));

		// Give account 11 some large free balance greater than total
		let _ = Balances::make_free_balance_be(&11, 1000000);

		// confirm that 10 is a normal validator and gets paid at the end of the era.
		mock::start_active_era(1);

		// Initial state of 10
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 1000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);

		mock::start_active_era(2);

		// Unbond some of the funds in stash.
		Staking::unbond(Origin::signed(10), 400).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 600,
				unlocking: vec![UnlockChunk { value: 400, era: 2 + 3 },],
				claimed_rewards: vec![],
			})
		);

		mock::start_active_era(3);

		// Unbond more of the funds in stash.
		Staking::unbond(Origin::signed(10), 300).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 300,
				unlocking: vec![
					UnlockChunk { value: 400, era: 2 + 3 },
					UnlockChunk { value: 300, era: 3 + 3 },
				],
				claimed_rewards: vec![],
			})
		);

		mock::start_active_era(4);

		// Unbond yet more of the funds in stash.
		Staking::unbond(Origin::signed(10), 200).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 100,
				unlocking: vec![
					UnlockChunk { value: 400, era: 2 + 3 },
					UnlockChunk { value: 300, era: 3 + 3 },
					UnlockChunk { value: 200, era: 4 + 3 },
				],
				claimed_rewards: vec![],
			})
		);

		// Re-bond half of the unbonding funds.
		Staking::rebond(Origin::signed(10), 400).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 500,
				unlocking: vec![
					UnlockChunk { value: 400, era: 2 + 3 },
					UnlockChunk { value: 100, era: 3 + 3 },
				],
				claimed_rewards: vec![],
			})
		);
	})
}

#[test]
fn rebond_emits_right_value_in_event() {
	// When a user calls rebond with more than can be rebonded, things succeed,
	// and the rebond event emits the actual value rebonded.
	ExtBuilder::default().nominate(false).build_and_execute(|| {
		// Set payee to controller. avoids confusion
		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));

		// Give account 11 some large free balance greater than total
		let _ = Balances::make_free_balance_be(&11, 1000000);

		// confirm that 10 is a normal validator and gets paid at the end of the era.
		mock::start_active_era(1);

		// Unbond almost all of the funds in stash.
		Staking::unbond(Origin::signed(10), 900).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 100,
				unlocking: vec![UnlockChunk { value: 900, era: 1 + 3 }],
				claimed_rewards: vec![],
			})
		);

		// Re-bond less than the total
		Staking::rebond(Origin::signed(10), 100).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 200,
				unlocking: vec![UnlockChunk { value: 800, era: 1 + 3 }],
				claimed_rewards: vec![],
			})
		);
		// Event emitted should be correct
		assert_eq!(*staking_events().last().unwrap(), Event::Bonded(11, 100));

		// Re-bond way more than available
		Staking::rebond(Origin::signed(10), 100_000).unwrap();
		assert_eq!(
			Staking::ledger(&10),
			Some(StakingLedger {
				stash: 11,
				total: 1000,
				active: 1000,
				unlocking: vec![],
				claimed_rewards: vec![],
			})
		);
		// Event emitted should be correct, only 800
		assert_eq!(*staking_events().last().unwrap(), Event::Bonded(11, 800));
	});
}

#[test]
fn reward_to_stake_works() {
	ExtBuilder::default()
		.nominate(false)
		.set_status(31, StakerStatus::Idle)
		.set_status(41, StakerStatus::Idle)
		.set_stake(21, 2000)
		.build_and_execute(|| {
			assert_eq!(Staking::validator_count(), 2);
			// Confirm account 10 and 20 are validators
			assert!(<Validators<Test>>::contains_key(&11) && <Validators<Test>>::contains_key(&21));

			assert_eq!(Staking::eras_stakers(active_era(), 11).total, 1000);
			assert_eq!(Staking::eras_stakers(active_era(), 21).total, 2000);

			// Give the man some money.
			let _ = Balances::make_free_balance_be(&10, 1000);
			let _ = Balances::make_free_balance_be(&20, 1000);

			// Bypass logic and change current exposure
			ErasStakers::<Test>::insert(0, 21, Exposure { total: 69, own: 69, others: vec![] });
			<Ledger<Test>>::insert(
				&20,
				StakingLedger {
					stash: 21,
					total: 69,
					active: 69,
					unlocking: vec![],
					claimed_rewards: vec![],
				},
			);

			// Compute total payout now for whole duration as other parameter won't change
			let total_payout_0 = current_total_payout_for_duration(reward_time_per_era());
			<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
			<Pallet<Test>>::reward_by_ids(vec![(21, 1)]);

			// New era --> rewards are paid --> stakes are changed
			mock::start_active_era(1);
			mock::make_all_reward_payment(0);

			assert_eq!(Staking::eras_stakers(active_era(), 11).total, 1000);
			assert_eq!(Staking::eras_stakers(active_era(), 21).total, 69);

			let _11_balance = Balances::free_balance(&11);
			assert_eq!(_11_balance, 1000 + total_payout_0 / 2);

			// Trigger another new era as the info are frozen before the era start.
			mock::start_active_era(2);

			// -- new infos
			assert_eq!(Staking::eras_stakers(active_era(), 11).total, 1000 + total_payout_0 / 2);
			assert_eq!(Staking::eras_stakers(active_era(), 21).total, 69 + total_payout_0 / 2);
		});
}

#[test]
fn reap_stash_works() {
	ExtBuilder::default()
		.existential_deposit(10)
		.balance_factor(10)
		.build_and_execute(|| {
			// given
			assert_eq!(Balances::free_balance(10), 10);
			assert_eq!(Balances::free_balance(11), 10 * 1000);
			assert_eq!(Staking::bonded(&11), Some(10));

			assert!(<Ledger<Test>>::contains_key(&10));
			assert!(<Bonded<Test>>::contains_key(&11));
			assert!(<Validators<Test>>::contains_key(&11));
			assert!(<Payee<Test>>::contains_key(&11));

			// stash is not reapable
			assert_noop!(
				Staking::reap_stash(Origin::signed(20), 11, 0),
				Error::<Test>::FundedTarget
			);
			// controller or any other account is not reapable
			assert_noop!(Staking::reap_stash(Origin::signed(20), 10, 0), Error::<Test>::NotStash);

			// no easy way to cause an account to go below ED, we tweak their staking ledger
			// instead.
			Ledger::<Test>::insert(
				10,
				StakingLedger {
					stash: 11,
					total: 5,
					active: 5,
					unlocking: vec![],
					claimed_rewards: vec![],
				},
			);

			// reap-able
			assert_ok!(Staking::reap_stash(Origin::signed(20), 11, 0));

			// then
			assert!(!<Ledger<Test>>::contains_key(&10));
			assert!(!<Bonded<Test>>::contains_key(&11));
			assert!(!<Validators<Test>>::contains_key(&11));
			assert!(!<Payee<Test>>::contains_key(&11));
		});
}

#[test]
fn switching_roles() {
	// Test that it should be possible to switch between roles (nominator, validator, idle) with
	// minimal overhead.
	ExtBuilder::default().nominate(false).build_and_execute(|| {
		// Reset reward destination
		for i in &[10, 20] {
			assert_ok!(Staking::set_payee(Origin::signed(*i), RewardDestination::Controller));
		}

		assert_eq_uvec!(validator_controllers(), vec![20, 10]);

		// put some money in account that we'll use.
		for i in 1..7 {
			let _ = Balances::deposit_creating(&i, 5000);
		}

		// add 2 nominators
		assert_ok!(Staking::bond(Origin::signed(1), 2, 2000, RewardDestination::Controller));
		assert_ok!(Staking::nominate(Origin::signed(2), vec![11, 5]));

		assert_ok!(Staking::bond(Origin::signed(3), 4, 500, RewardDestination::Controller));
		assert_ok!(Staking::nominate(Origin::signed(4), vec![21, 1]));

		// add a new validator candidate
		assert_ok!(Staking::bond(Origin::signed(5), 6, 1000, RewardDestination::Controller));
		assert_ok!(Staking::validate(Origin::signed(6), ValidatorPrefs::default()));

		mock::start_active_era(1);

		// with current nominators 10 and 5 have the most stake
		assert_eq_uvec!(validator_controllers(), vec![6, 10]);

		// 2 decides to be a validator. Consequences:
		assert_ok!(Staking::validate(Origin::signed(2), ValidatorPrefs::default()));
		// new stakes:
		// 10: 1000 self vote
		// 20: 1000 self vote + 250 vote
		// 6 : 1000 self vote
		// 2 : 2000 self vote + 250 vote.
		// Winners: 20 and 2

		mock::start_active_era(2);

		assert_eq_uvec!(validator_controllers(), vec![2, 20]);
	});
}

#[test]
fn wrong_vote_is_moot() {
	ExtBuilder::default()
		.add_staker(
			61,
			60,
			500,
			StakerStatus::Nominator(vec![
				11, 21, // good votes
				1, 2, 15, 1000, 25, // crap votes. No effect.
			]),
		)
		.build_and_execute(|| {
			// the genesis validators already reflect the above vote, nonetheless start a new era.
			mock::start_active_era(1);

			// new validators
			assert_eq_uvec!(validator_controllers(), vec![20, 10]);

			// our new voter is taken into account
			assert!(Staking::eras_stakers(active_era(), 11).others.iter().any(|i| i.who == 61));
			assert!(Staking::eras_stakers(active_era(), 21).others.iter().any(|i| i.who == 61));
		});
}

#[test]
fn bond_with_no_staked_value() {
	// Behavior when someone bonds with no staked value.
	// Particularly when she votes and the candidate is elected.
	ExtBuilder::default()
		.validator_count(3)
		.existential_deposit(5)
		.balance_factor(5)
		.nominate(false)
		.minimum_validator_count(1)
		.build_and_execute(|| {
			// Can't bond with 1
			assert_noop!(
				Staking::bond(Origin::signed(1), 2, 1, RewardDestination::Controller),
				Error::<Test>::InsufficientBond,
			);
			// bonded with absolute minimum value possible.
			assert_ok!(Staking::bond(Origin::signed(1), 2, 5, RewardDestination::Controller));
			assert_eq!(Balances::locks(&1)[0].amount, 5);

			// unbonding even 1 will cause all to be unbonded.
			assert_ok!(Staking::unbond(Origin::signed(2), 1));
			assert_eq!(
				Staking::ledger(2),
				Some(StakingLedger {
					stash: 1,
					active: 0,
					total: 5,
					unlocking: vec![UnlockChunk { value: 5, era: 3 }],
					claimed_rewards: vec![],
				})
			);

			mock::start_active_era(1);
			mock::start_active_era(2);

			// not yet removed.
			assert_ok!(Staking::withdraw_unbonded(Origin::signed(2), 0));
			assert!(Staking::ledger(2).is_some());
			assert_eq!(Balances::locks(&1)[0].amount, 5);

			mock::start_active_era(3);

			// poof. Account 1 is removed from the staking system.
			assert_ok!(Staking::withdraw_unbonded(Origin::signed(2), 0));
			assert!(Staking::ledger(2).is_none());
			assert_eq!(Balances::locks(&1).len(), 0);
		});
}

#[test]
fn bond_with_little_staked_value_bounded() {
	ExtBuilder::default()
		.validator_count(3)
		.nominate(false)
		.minimum_validator_count(1)
		.build_and_execute(|| {
			// setup
			assert_ok!(Staking::chill(Origin::signed(30)));
			assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));
			let init_balance_2 = Balances::free_balance(&2);
			let init_balance_10 = Balances::free_balance(&10);

			// Stingy validator.
			assert_ok!(Staking::bond(Origin::signed(1), 2, 1, RewardDestination::Controller));
			assert_ok!(Staking::validate(Origin::signed(2), ValidatorPrefs::default()));

			// 1 era worth of reward. BUT, we set the timestamp after on_initialize, so outdated by
			// one block.
			let total_payout_0 = current_total_payout_for_duration(reward_time_per_era());

			reward_all_elected();
			mock::start_active_era(1);
			mock::make_all_reward_payment(0);

			// 2 is elected.
			assert_eq_uvec!(validator_controllers(), vec![20, 10, 2]);
			assert_eq!(Staking::eras_stakers(active_era(), 2).total, 0);

			// Old ones are rewarded.
			assert_eq_error_rate!(
				Balances::free_balance(10),
				init_balance_10 + total_payout_0 / 3,
				1
			);
			// no rewards paid to 2. This was initial election.
			assert_eq!(Balances::free_balance(2), init_balance_2);

			// reward era 2
			let total_payout_1 = current_total_payout_for_duration(reward_time_per_era());
			reward_all_elected();
			mock::start_active_era(2);
			mock::make_all_reward_payment(1);

			assert_eq_uvec!(validator_controllers(), vec![20, 10, 2]);
			assert_eq!(Staking::eras_stakers(active_era(), 2).total, 0);

			// 2 is now rewarded.
			assert_eq_error_rate!(
				Balances::free_balance(2),
				init_balance_2 + total_payout_1 / 3,
				1
			);
			assert_eq_error_rate!(
				Balances::free_balance(&10),
				init_balance_10 + total_payout_0 / 3 + total_payout_1 / 3,
				2,
			);
		});
}

#[test]
fn bond_with_duplicate_vote_should_be_ignored_by_election_provider() {
	ExtBuilder::default()
		.validator_count(2)
		.nominate(false)
		.minimum_validator_count(1)
		.set_stake(31, 1000)
		.build_and_execute(|| {
			// ensure all have equal stake.
			assert_eq!(
				<Validators<Test>>::iter()
					.map(|(v, _)| (v, Staking::ledger(v - 1).unwrap().total))
					.collect::<Vec<_>>(),
				vec![(31, 1000), (21, 1000), (11, 1000)],
			);
			// no nominators shall exist.
			assert!(<Nominators<Test>>::iter().map(|(n, _)| n).collect::<Vec<_>>().is_empty());

			// give the man some money.
			let initial_balance = 1000;
			for i in [1, 2, 3, 4].iter() {
				let _ = Balances::make_free_balance_be(i, initial_balance);
			}

			assert_ok!(Staking::bond(Origin::signed(1), 2, 1000, RewardDestination::Controller));
			assert_ok!(Staking::nominate(Origin::signed(2), vec![11, 11, 11, 21, 31]));

			assert_ok!(Staking::bond(Origin::signed(3), 4, 1000, RewardDestination::Controller));
			assert_ok!(Staking::nominate(Origin::signed(4), vec![21, 31]));

			// winners should be 21 and 31. Otherwise this election is taking duplicates into
			// account.
			let supports = <Test as Config>::ElectionProvider::elect().unwrap();
			assert_eq!(
				supports,
				vec![
					(21, Support { total: 1800, voters: vec![(21, 1000), (1, 400), (3, 400)] }),
					(31, Support { total: 2200, voters: vec![(31, 1000), (1, 600), (3, 600)] })
				],
			);
		});
}

#[test]
fn bond_with_duplicate_vote_should_be_ignored_by_election_provider_elected() {
	// same as above but ensures that even when the dupe is being elected, everything is sane.
	ExtBuilder::default()
		.validator_count(2)
		.nominate(false)
		.set_stake(31, 1000)
		.minimum_validator_count(1)
		.build_and_execute(|| {
			// ensure all have equal stake.
			assert_eq!(
				<Validators<Test>>::iter()
					.map(|(v, _)| (v, Staking::ledger(v - 1).unwrap().total))
					.collect::<Vec<_>>(),
				vec![(31, 1000), (21, 1000), (11, 1000)],
			);

			// no nominators shall exist.
			assert!(<Nominators<Test>>::iter().collect::<Vec<_>>().is_empty());

			// give the man some money.
			let initial_balance = 1000;
			for i in [1, 2, 3, 4].iter() {
				let _ = Balances::make_free_balance_be(i, initial_balance);
			}

			assert_ok!(Staking::bond(Origin::signed(1), 2, 1000, RewardDestination::Controller));
			assert_ok!(Staking::nominate(Origin::signed(2), vec![11, 11, 11, 21]));

			assert_ok!(Staking::bond(Origin::signed(3), 4, 1000, RewardDestination::Controller));
			assert_ok!(Staking::nominate(Origin::signed(4), vec![21]));

			// winners should be 21 and 11.
			let supports = <Test as Config>::ElectionProvider::elect().unwrap();
			assert_eq!(
				supports,
				vec![
					(11, Support { total: 1500, voters: vec![(11, 1000), (1, 500)] }),
					(21, Support { total: 2500, voters: vec![(21, 1000), (1, 500), (3, 1000)] })
				],
			);
		});
}

#[test]
fn new_era_elects_correct_number_of_validators() {
	ExtBuilder::default().nominate(true).validator_count(1).build_and_execute(|| {
		assert_eq!(Staking::validator_count(), 1);
		assert_eq!(validator_controllers().len(), 1);

		Session::on_initialize(System::block_number());

		assert_eq!(validator_controllers().len(), 1);
	})
}

#[test]
fn phragmen_should_not_overflow() {
	ExtBuilder::default().nominate(false).build_and_execute(|| {
		// This is the maximum value that we can have as the outcome of CurrencyToVote.
		type Votes = u64;

		let _ = Staking::chill(Origin::signed(10));
		let _ = Staking::chill(Origin::signed(20));

		bond_validator(3, 2, Votes::max_value() as Balance);
		bond_validator(5, 4, Votes::max_value() as Balance);

		bond_nominator(7, 6, Votes::max_value() as Balance, vec![3, 5]);
		bond_nominator(9, 8, Votes::max_value() as Balance, vec![3, 5]);

		mock::start_active_era(1);

		assert_eq_uvec!(validator_controllers(), vec![4, 2]);

		// We can safely convert back to values within [u64, u128].
		assert!(Staking::eras_stakers(active_era(), 3).total > Votes::max_value() as Balance);
		assert!(Staking::eras_stakers(active_era(), 5).total > Votes::max_value() as Balance);
	})
}

#[test]
fn reward_validator_slashing_validator_does_not_overflow() {
	ExtBuilder::default().build_and_execute(|| {
		let stake = u64::MAX as Balance * 2;
		let reward_slash = u64::MAX as Balance * 2;

		// Assert multiplication overflows in balance arithmetic.
		assert!(stake.checked_mul(reward_slash).is_none());

		// Set staker