Treasury spends various asset kinds (#1333)

### Summary 

This PR introduces new dispatchables to the treasury pallet, allowing
spends of various asset types. The enhanced features of the treasury
pallet, in conjunction with the asset-rate pallet, are set up and
enabled for Westend and Rococo.

### Westend and Rococo runtimes.

Polkadot/Kusams/Rococo Treasury can accept proposals for `spends` of
various asset kinds by specifying the asset's location and ID.

#### Treasury Instance New Dispatchables:
- `spend(AssetKind, AssetBalance, Beneficiary, Option<ValidFrom>)` -
propose and approve a spend;
- `payout(SpendIndex)` - payout an approved spend or retry a failed
payout
- `check_payment(SpendIndex)` - check the status of a payout;
- `void_spend(SpendIndex)` - void previously approved spend;
> existing spend dispatchable renamed to spend_local

in this context, the `AssetKind` parameter contains the asset's location
and it's corresponding `asset_id`, for example:
`USDT` on `AssetHub`,
``` rust
location = MultiLocation(0, X1(Parachain(1000)))
asset_id = MultiLocation(0, X2(PalletInstance(50), GeneralIndex(1984)))
```

the `Beneficiary` parameter is a `MultiLocation` in the context of the
asset's location, for example
``` rust
// the Fellowship salary pallet's location / account
FellowshipSalaryPallet = MultiLocation(1, X2(Parachain(1001), PalletInstance(64)))
// or custom `AccountId`
Alice = MultiLocation(0, AccountId32(network: None, id: [1,...]))
```

the `AssetBalance` represents the amount of the `AssetKind` to be
transferred to the `Beneficiary`. For permission checks, the asset
amount is converted to the native amount and compared against the
maximum spendable amount determined by the commanding spend origin.

the `spend` dispatchable allows for batching spends with different
`ValidFrom` arguments, enabling milestone-based spending. If the
expectations tied to an approved spend are not met, it is possible to
void the spend later using the `void_spend` dispatchable.

Asset Rate Pallet provides the conversion rate from the `AssetKind` to
the native balance.

#### Asset Rate Instance Dispatchables:
- `create(AssetKind, Rate)` - initialize a conversion rate to the native
balance for the given asset
- `update(AssetKind, Rate)` - update the conversion rate to the native
balance for the given asset
- `remove(AssetKind)` - remove an existing conversion rate to the native
balance for the given asset

the pallet's dispatchables can be executed by the Root or Treasurer
origins.

### Treasury Pallet

Treasury Pallet can accept proposals for `spends` of various asset kinds
and pay them out through the implementation of the `Pay` trait.

New Dispatchables:
- `spend(Config::AssetKind, AssetBalance, Config::Beneficiary,
Option<ValidFrom>)` - propose and approve a spend;
- `payout(SpendIndex)` - payout an approved spend or retry a failed
payout;
- `check_payment(SpendIndex)` - check the status of a payout;
- `void_spend(SpendIndex)` - void previously approved spend;
> existing spend dispatchable renamed to spend_local

The parameters' types of the `spend` dispatchable exposed via the
pallet's `Config` and allows to propose and accept a spend of a certain
amount.

An approved spend can be claimed via the `payout` within the
`Config::SpendPeriod`. Clients provide an implementation of the `Pay`
trait which can pay an asset of the `AssetKind` to the `Beneficiary` in
`AssetBalance` units.

The implementation of the Pay trait might not have an immediate final
payment status, for example if implemented over `XCM` and the actual
transfer happens on a remote chain.

The `check_status` dispatchable can be executed to update the spend's
payment state and retry the `payout` if the payment has failed.

---------

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
Co-authored-by: command-bot <>
This commit is contained in:
Muharem
2023-10-07 19:32:35 +02:00
committed by GitHub
parent 5a6912606a
commit cb944dc548
32 changed files with 2213 additions and 286 deletions
+405 -23
View File
@@ -19,6 +19,7 @@
#![cfg(test)]
use core::{cell::RefCell, marker::PhantomData};
use sp_core::H256;
use sp_runtime::{
traits::{BadOrigin, BlakeTwo256, Dispatchable, IdentityLookup},
@@ -26,8 +27,13 @@ use sp_runtime::{
};
use frame_support::{
assert_err_ignore_postinfo, assert_noop, assert_ok, parameter_types,
traits::{ConstU32, ConstU64, OnInitialize},
assert_err_ignore_postinfo, assert_noop, assert_ok,
pallet_prelude::Pays,
parameter_types,
traits::{
tokens::{ConversionFromAssetBalance, PaymentStatus},
ConstU32, ConstU64, OnInitialize,
},
PalletId,
};
@@ -96,10 +102,64 @@ impl pallet_utility::Config for Test {
type WeightInfo = ();
}
thread_local! {
pub static PAID: RefCell<BTreeMap<(u128, u32), u64>> = RefCell::new(BTreeMap::new());
pub static STATUS: RefCell<BTreeMap<u64, PaymentStatus>> = RefCell::new(BTreeMap::new());
pub static LAST_ID: RefCell<u64> = RefCell::new(0u64);
}
/// paid balance for a given account and asset ids
fn paid(who: u128, asset_id: u32) -> u64 {
PAID.with(|p| p.borrow().get(&(who, asset_id)).cloned().unwrap_or(0))
}
/// reduce paid balance for a given account and asset ids
fn unpay(who: u128, asset_id: u32, amount: u64) {
PAID.with(|p| p.borrow_mut().entry((who, asset_id)).or_default().saturating_reduce(amount))
}
/// set status for a given payment id
fn set_status(id: u64, s: PaymentStatus) {
STATUS.with(|m| m.borrow_mut().insert(id, s));
}
pub struct TestPay;
impl Pay for TestPay {
type Beneficiary = u128;
type Balance = u64;
type Id = u64;
type AssetKind = u32;
type Error = ();
fn pay(
who: &Self::Beneficiary,
asset_kind: Self::AssetKind,
amount: Self::Balance,
) -> Result<Self::Id, Self::Error> {
PAID.with(|paid| *paid.borrow_mut().entry((*who, asset_kind)).or_default() += amount);
Ok(LAST_ID.with(|lid| {
let x = *lid.borrow();
lid.replace(x + 1);
x
}))
}
fn check_payment(id: Self::Id) -> PaymentStatus {
STATUS.with(|s| s.borrow().get(&id).cloned().unwrap_or(PaymentStatus::Unknown))
}
#[cfg(feature = "runtime-benchmarks")]
fn ensure_successful(_: &Self::Beneficiary, _: Self::AssetKind, _: Self::Balance) {}
#[cfg(feature = "runtime-benchmarks")]
fn ensure_concluded(id: Self::Id) {
set_status(id, PaymentStatus::Failure)
}
}
parameter_types! {
pub const ProposalBond: Permill = Permill::from_percent(5);
pub const Burn: Permill = Permill::from_percent(50);
pub const TreasuryPalletId: PalletId = PalletId(*b"py/trsry");
pub TreasuryAccount: u128 = Treasury::account_id();
pub const SpendPayoutPeriod: u64 = 5;
}
pub struct TestSpendOrigin;
impl frame_support::traits::EnsureOrigin<RuntimeOrigin> for TestSpendOrigin {
@@ -120,6 +180,16 @@ impl frame_support::traits::EnsureOrigin<RuntimeOrigin> for TestSpendOrigin {
}
}
pub struct MulBy<N>(PhantomData<N>);
impl<N: Get<u64>> ConversionFromAssetBalance<u64, u32, u64> for MulBy<N> {
type Error = ();
fn from_asset_balance(balance: u64, _asset_id: u32) -> Result<u64, Self::Error> {
return balance.checked_mul(N::get()).ok_or(())
}
#[cfg(feature = "runtime-benchmarks")]
fn ensure_successful(_: u32) {}
}
impl Config for Test {
type PalletId = TreasuryPalletId;
type Currency = pallet_balances::Pallet<Test>;
@@ -137,6 +207,14 @@ impl Config for Test {
type SpendFunds = ();
type MaxApprovals = ConstU32<100>;
type SpendOrigin = TestSpendOrigin;
type AssetKind = u32;
type Beneficiary = u128;
type BeneficiaryLookup = IdentityLookup<Self::Beneficiary>;
type Paymaster = TestPay;
type BalanceConverter = MulBy<ConstU64<2>>;
type PayoutPeriod = SpendPayoutPeriod;
#[cfg(feature = "runtime-benchmarks")]
type BenchmarkHelper = ();
}
pub fn new_test_ext() -> sp_io::TestExternalities {
@@ -151,6 +229,14 @@ pub fn new_test_ext() -> sp_io::TestExternalities {
t.into()
}
fn get_payment_id(i: SpendIndex) -> Option<u64> {
let spend = Spends::<Test, _>::get(i).expect("no spend");
match spend.status {
PaymentState::Attempted { id } => Some(id),
_ => None,
}
}
#[test]
fn genesis_config_works() {
new_test_ext().execute_with(|| {
@@ -160,46 +246,49 @@ fn genesis_config_works() {
}
#[test]
fn spend_origin_permissioning_works() {
fn spend_local_origin_permissioning_works() {
new_test_ext().execute_with(|| {
assert_noop!(Treasury::spend(RuntimeOrigin::signed(1), 1, 1), BadOrigin);
assert_noop!(Treasury::spend_local(RuntimeOrigin::signed(1), 1, 1), BadOrigin);
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(10), 6, 1),
Treasury::spend_local(RuntimeOrigin::signed(10), 6, 1),
Error::<Test>::InsufficientPermission
);
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(11), 11, 1),
Treasury::spend_local(RuntimeOrigin::signed(11), 11, 1),
Error::<Test>::InsufficientPermission
);
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(12), 21, 1),
Treasury::spend_local(RuntimeOrigin::signed(12), 21, 1),
Error::<Test>::InsufficientPermission
);
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(13), 51, 1),
Treasury::spend_local(RuntimeOrigin::signed(13), 51, 1),
Error::<Test>::InsufficientPermission
);
});
}
#[docify::export]
#[test]
fn spend_origin_works() {
fn spend_local_origin_works() {
new_test_ext().execute_with(|| {
// Check that accumulate works when we have Some value in Dummy already.
Balances::make_free_balance_be(&Treasury::account_id(), 101);
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend(RuntimeOrigin::signed(11), 10, 6));
assert_ok!(Treasury::spend(RuntimeOrigin::signed(12), 20, 6));
assert_ok!(Treasury::spend(RuntimeOrigin::signed(13), 50, 6));
// approve spend of some amount to beneficiary `6`.
assert_ok!(Treasury::spend_local(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend_local(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend_local(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend_local(RuntimeOrigin::signed(10), 5, 6));
assert_ok!(Treasury::spend_local(RuntimeOrigin::signed(11), 10, 6));
assert_ok!(Treasury::spend_local(RuntimeOrigin::signed(12), 20, 6));
assert_ok!(Treasury::spend_local(RuntimeOrigin::signed(13), 50, 6));
// free balance of `6` is zero, spend period has not passed.
<Treasury as OnInitialize<u64>>::on_initialize(1);
assert_eq!(Balances::free_balance(6), 0);
// free balance of `6` is `100`, spend period has passed.
<Treasury as OnInitialize<u64>>::on_initialize(2);
assert_eq!(Balances::free_balance(6), 100);
// `100` spent, `1` burned.
assert_eq!(Treasury::pot(), 0);
});
}
@@ -579,13 +668,13 @@ fn remove_already_removed_approval_fails() {
}
#[test]
fn spending_in_batch_respects_max_total() {
fn spending_local_in_batch_respects_max_total() {
new_test_ext().execute_with(|| {
// Respect the `max_total` for the given origin.
assert_ok!(RuntimeCall::from(UtilityCall::batch_all {
calls: vec![
RuntimeCall::from(TreasuryCall::spend { amount: 2, beneficiary: 100 }),
RuntimeCall::from(TreasuryCall::spend { amount: 2, beneficiary: 101 })
RuntimeCall::from(TreasuryCall::spend_local { amount: 2, beneficiary: 100 }),
RuntimeCall::from(TreasuryCall::spend_local { amount: 2, beneficiary: 101 })
]
})
.dispatch(RuntimeOrigin::signed(10)));
@@ -593,8 +682,8 @@ fn spending_in_batch_respects_max_total() {
assert_err_ignore_postinfo!(
RuntimeCall::from(UtilityCall::batch_all {
calls: vec![
RuntimeCall::from(TreasuryCall::spend { amount: 2, beneficiary: 100 }),
RuntimeCall::from(TreasuryCall::spend { amount: 4, beneficiary: 101 })
RuntimeCall::from(TreasuryCall::spend_local { amount: 2, beneficiary: 100 }),
RuntimeCall::from(TreasuryCall::spend_local { amount: 4, beneficiary: 101 })
]
})
.dispatch(RuntimeOrigin::signed(10)),
@@ -602,3 +691,296 @@ fn spending_in_batch_respects_max_total() {
);
})
}
#[test]
fn spending_in_batch_respects_max_total() {
new_test_ext().execute_with(|| {
// Respect the `max_total` for the given origin.
assert_ok!(RuntimeCall::from(UtilityCall::batch_all {
calls: vec![
RuntimeCall::from(TreasuryCall::spend {
asset_kind: Box::new(1),
amount: 1,
beneficiary: Box::new(100),
valid_from: None,
}),
RuntimeCall::from(TreasuryCall::spend {
asset_kind: Box::new(1),
amount: 1,
beneficiary: Box::new(101),
valid_from: None,
})
]
})
.dispatch(RuntimeOrigin::signed(10)));
assert_err_ignore_postinfo!(
RuntimeCall::from(UtilityCall::batch_all {
calls: vec![
RuntimeCall::from(TreasuryCall::spend {
asset_kind: Box::new(1),
amount: 2,
beneficiary: Box::new(100),
valid_from: None,
}),
RuntimeCall::from(TreasuryCall::spend {
asset_kind: Box::new(1),
amount: 2,
beneficiary: Box::new(101),
valid_from: None,
})
]
})
.dispatch(RuntimeOrigin::signed(10)),
Error::<Test, _>::InsufficientPermission
);
})
}
#[test]
fn spend_origin_works() {
new_test_ext().execute_with(|| {
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 1, Box::new(6), None));
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 3, Box::new(6), None),
Error::<Test, _>::InsufficientPermission
);
assert_ok!(Treasury::spend(RuntimeOrigin::signed(11), Box::new(1), 5, Box::new(6), None));
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(11), Box::new(1), 6, Box::new(6), None),
Error::<Test, _>::InsufficientPermission
);
assert_ok!(Treasury::spend(RuntimeOrigin::signed(12), Box::new(1), 10, Box::new(6), None));
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(12), Box::new(1), 11, Box::new(6), None),
Error::<Test, _>::InsufficientPermission
);
assert_eq!(SpendCount::<Test, _>::get(), 4);
assert_eq!(Spends::<Test, _>::iter().count(), 4);
});
}
#[test]
fn spend_works() {
new_test_ext().execute_with(|| {
System::set_block_number(1);
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
assert_eq!(SpendCount::<Test, _>::get(), 1);
assert_eq!(
Spends::<Test, _>::get(0).unwrap(),
SpendStatus {
asset_kind: 1,
amount: 2,
beneficiary: 6,
valid_from: 1,
expire_at: 6,
status: PaymentState::Pending,
}
);
System::assert_last_event(
Event::<Test, _>::AssetSpendApproved {
index: 0,
asset_kind: 1,
amount: 2,
beneficiary: 6,
valid_from: 1,
expire_at: 6,
}
.into(),
);
});
}
#[test]
fn spend_expires() {
new_test_ext().execute_with(|| {
assert_eq!(<Test as Config>::PayoutPeriod::get(), 5);
// spend `0` expires in 5 blocks after the creating.
System::set_block_number(1);
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
System::set_block_number(6);
assert_noop!(Treasury::payout(RuntimeOrigin::signed(1), 0), Error::<Test, _>::SpendExpired);
// spend cannot be approved since its already expired.
assert_noop!(
Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), Some(0)),
Error::<Test, _>::SpendExpired
);
});
}
#[docify::export]
#[test]
fn spend_payout_works() {
new_test_ext().execute_with(|| {
System::set_block_number(1);
// approve a `2` coins spend of asset `1` to beneficiary `6`, the spend valid from now.
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
// payout the spend.
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 0));
// beneficiary received `2` coins of asset `1`.
assert_eq!(paid(6, 1), 2);
assert_eq!(SpendCount::<Test, _>::get(), 1);
let payment_id = get_payment_id(0).expect("no payment attempt");
System::assert_last_event(Event::<Test, _>::Paid { index: 0, payment_id }.into());
set_status(payment_id, PaymentStatus::Success);
// the payment succeed.
assert_ok!(Treasury::check_status(RuntimeOrigin::signed(1), 0));
System::assert_last_event(Event::<Test, _>::SpendProcessed { index: 0 }.into());
// cannot payout the same spend twice.
assert_noop!(Treasury::payout(RuntimeOrigin::signed(1), 0), Error::<Test, _>::InvalidIndex);
});
}
#[test]
fn payout_retry_works() {
new_test_ext().execute_with(|| {
System::set_block_number(1);
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 0));
assert_eq!(paid(6, 1), 2);
let payment_id = get_payment_id(0).expect("no payment attempt");
// spend payment is failed
set_status(payment_id, PaymentStatus::Failure);
unpay(6, 1, 2);
// cannot payout a spend in the attempted state
assert_noop!(
Treasury::payout(RuntimeOrigin::signed(1), 0),
Error::<Test, _>::AlreadyAttempted
);
// check status and update it to retry the payout again
assert_ok!(Treasury::check_status(RuntimeOrigin::signed(1), 0));
System::assert_last_event(Event::<Test, _>::PaymentFailed { index: 0, payment_id }.into());
// the payout can be retried now
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 0));
assert_eq!(paid(6, 1), 2);
});
}
#[test]
fn spend_valid_from_works() {
new_test_ext().execute_with(|| {
assert_eq!(<Test as Config>::PayoutPeriod::get(), 5);
System::set_block_number(1);
// spend valid from block `2`.
assert_ok!(Treasury::spend(
RuntimeOrigin::signed(10),
Box::new(1),
2,
Box::new(6),
Some(2)
));
assert_noop!(Treasury::payout(RuntimeOrigin::signed(1), 0), Error::<Test, _>::EarlyPayout);
System::set_block_number(2);
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 0));
System::set_block_number(5);
// spend approved even if `valid_from` in the past since the payout period has not passed.
assert_ok!(Treasury::spend(
RuntimeOrigin::signed(10),
Box::new(1),
2,
Box::new(6),
Some(4)
));
// spend paid.
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 1));
});
}
#[test]
fn void_spend_works() {
new_test_ext().execute_with(|| {
System::set_block_number(1);
// spend cannot be voided if already attempted.
assert_ok!(Treasury::spend(
RuntimeOrigin::signed(10),
Box::new(1),
2,
Box::new(6),
Some(1)
));
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 0));
assert_noop!(
Treasury::void_spend(RuntimeOrigin::root(), 0),
Error::<Test, _>::AlreadyAttempted
);
// void spend.
assert_ok!(Treasury::spend(
RuntimeOrigin::signed(10),
Box::new(1),
2,
Box::new(6),
Some(10)
));
assert_ok!(Treasury::void_spend(RuntimeOrigin::root(), 1));
assert_eq!(Spends::<Test, _>::get(1), None);
});
}
#[test]
fn check_status_works() {
new_test_ext().execute_with(|| {
assert_eq!(<Test as Config>::PayoutPeriod::get(), 5);
System::set_block_number(1);
// spend `0` expired and can be removed.
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
System::set_block_number(7);
let info = Treasury::check_status(RuntimeOrigin::signed(1), 0).unwrap();
assert_eq!(info.pays_fee, Pays::No);
System::assert_last_event(Event::<Test, _>::SpendProcessed { index: 0 }.into());
// spend `1` payment failed and expired hence can be removed.
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
assert_noop!(
Treasury::check_status(RuntimeOrigin::signed(1), 1),
Error::<Test, _>::NotAttempted
);
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 1));
let payment_id = get_payment_id(1).expect("no payment attempt");
set_status(payment_id, PaymentStatus::Failure);
// spend expired.
System::set_block_number(13);
let info = Treasury::check_status(RuntimeOrigin::signed(1), 1).unwrap();
assert_eq!(info.pays_fee, Pays::Yes);
System::assert_last_event(Event::<Test, _>::PaymentFailed { index: 1, payment_id }.into());
let info = Treasury::check_status(RuntimeOrigin::signed(1), 1).unwrap();
assert_eq!(info.pays_fee, Pays::No);
System::assert_last_event(Event::<Test, _>::SpendProcessed { index: 1 }.into());
// spend `2` payment succeed.
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 2));
let payment_id = get_payment_id(2).expect("no payment attempt");
set_status(payment_id, PaymentStatus::Success);
let info = Treasury::check_status(RuntimeOrigin::signed(1), 2).unwrap();
assert_eq!(info.pays_fee, Pays::No);
System::assert_last_event(Event::<Test, _>::SpendProcessed { index: 2 }.into());
// spend `3` payment in process.
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 3));
let payment_id = get_payment_id(3).expect("no payment attempt");
set_status(payment_id, PaymentStatus::InProgress);
assert_noop!(
Treasury::check_status(RuntimeOrigin::signed(1), 3),
Error::<Test, _>::Inconclusive
);
// spend `4` removed since the payment status is unknown.
assert_ok!(Treasury::spend(RuntimeOrigin::signed(10), Box::new(1), 2, Box::new(6), None));
assert_ok!(Treasury::payout(RuntimeOrigin::signed(1), 4));
let payment_id = get_payment_id(4).expect("no payment attempt");
set_status(payment_id, PaymentStatus::Unknown);
let info = Treasury::check_status(RuntimeOrigin::signed(1), 4).unwrap();
assert_eq!(info.pays_fee, Pays::No);
System::assert_last_event(Event::<Test, _>::SpendProcessed { index: 4 }.into());
});
}