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Add Mint Cap to Bonding Curve #119

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Merged
Joeysantoro merged 1 commit into from
Aug 6, 2021
Merged

Add Mint Cap to Bonding Curve #119

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25 changes: 25 additions & 0 deletions contracts/bondingcurve/BondingCurve.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,9 @@ contract BondingCurve is IBondingCurve, OracleRef, PCVSplitter, Timed, Incentivi
/// @notice the discount applied on top of peg before at Scale
uint256 public override discount;

/// @notice the cap on how much FEI can be minted by the bonding curve
uint256 public override mintCap;
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@sol-sr sol-sr Aug 4, 2021

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When we upgrade the contracts, are we doing it with a proxy/storage pattern or some other method?
If we are using a proxy/storage pattern, the variable should be added after BASIS_POINTS_GRANULARITY.

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@Joeysantoro Joeysantoro Aug 4, 2021

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We don't use proxy/storage its just drop-and-replace


uint256 public constant BASIS_POINTS_GRANULARITY = 10_000;

/// @notice constructor
Expand Down Expand Up @@ -64,6 +67,7 @@ contract BondingCurve is IBondingCurve, OracleRef, PCVSplitter, Timed, Incentivi
Timed(_duration)
Incentivized(_incentive)
{
_setMintCap(_scale); // default mint cap is scale
_setScale(_scale);
token = _token;

Expand Down Expand Up @@ -142,6 +146,11 @@ contract BondingCurve is IBondingCurve, OracleRef, PCVSplitter, Timed, Incentivi
_setDuration(_frequency);
}

/// @notice sets the mint cap for the bonding curve
function setMintCap(uint256 _mintCap) external override onlyGovernor {
_setMintCap(_mintCap);
}

/// @notice sets the allocation of incoming PCV
function setAllocation(
address[] calldata allocations,
Expand Down Expand Up @@ -176,6 +185,11 @@ contract BondingCurve is IBondingCurve, OracleRef, PCVSplitter, Timed, Incentivi
return totalPurchased >= scale;
}

/// @notice returns how close to the minting cap we are
function availableToMint() public view override returns (uint256) {
return mintCap - totalPurchased;
}

/// @notice return current instantaneous bonding curve price
/// @return price reported as FEI per USD
/// @dev Can be inaccurate if outdated, need to call `oracle().isOutdated()` to check
Expand Down Expand Up @@ -229,6 +243,8 @@ contract BondingCurve is IBondingCurve, OracleRef, PCVSplitter, Timed, Incentivi

amountOut = getAmountOut(amountIn);

require(availableToMint() >= amountOut, "BondingCurve: exceeds mint cap");

_incrementTotalPurchased(amountOut);
fei().mint(to, amountOut);

Expand All @@ -249,6 +265,15 @@ contract BondingCurve is IBondingCurve, OracleRef, PCVSplitter, Timed, Incentivi
emit ScaleUpdate(oldScale, newScale);
}

function _setMintCap(uint256 newMintCap) internal {
require(newMintCap != 0, "BondingCurve: zero mint cap");

uint256 oldMintCap = mintCap;
mintCap = newMintCap;

emit MintCapUpdate(oldMintCap, newMintCap);
}

/// @notice the bonding curve price multiplier used before Scale
function _getBondingCurvePriceMultiplier()
internal
Expand Down
7 changes: 7 additions & 0 deletions contracts/bondingcurve/IBondingCurve.sol
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Expand Up @@ -9,6 +9,8 @@ interface IBondingCurve {

event ScaleUpdate(uint256 oldScale, uint256 newScale);

event MintCapUpdate(uint256 oldMint, uint256 newMint);

event BufferUpdate(uint256 oldBuffer, uint256 newBuffer);

event DiscountUpdate(uint256 oldDiscount, uint256 newDiscount);
Expand Down Expand Up @@ -45,6 +47,8 @@ interface IBondingCurve {

function setIncentiveFrequency(uint256 newFrequency) external;

function setMintCap(uint256 newMintCap) external;

// ----------- Getters -----------

function getCurrentPrice() external view returns (Decimal.D256 memory);
Expand All @@ -68,4 +72,7 @@ interface IBondingCurve {

function token() external view returns (IERC20);

function mintCap() external view returns (uint256);

function availableToMint() external view returns (uint256);
}
13 changes: 12 additions & 1 deletion test/bondingcurve/BondingCurve.test.js
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Expand Up @@ -61,6 +61,8 @@ describe('BondingCurve', function () {

await this.token.mint(userAddress, '1000000000000000000000000');
await this.core.grantMinter(this.bondingCurve.address, {from: governorAddress});

await this.bondingCurve.setMintCap(this.scale.mul(new BN('10')), {from: governorAddress});
});

describe('Init', function() {
Expand Down Expand Up @@ -270,7 +272,16 @@ describe('BondingCurve', function () {
});
});
});

describe('Exceeding cap', function() {
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@sebastiandelgado sebastiandelgado Aug 4, 2021

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Can't tell if there is a test in this file that buys under the mint cap to check that its still possible to buy even with the mint cap on

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@sol-sr sol-sr Aug 4, 2021

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To add to this point, I only see purchasing happening in the before each hook and we don't verify the fei they received. Recommend adding a test purchasing from the bonding curve that actually succeeds. After the success, we should verify FEI balances and that the bonding curve or receiving contract's eth balance incremented.

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@Joeysantoro Joeysantoro Aug 4, 2021

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There are tests for the FEI being received higher up in the file

it('reverts', async function() {
this.purchaseAmount = new BN('4000000000');
await this.token.approve(this.bondingCurve.address, this.purchaseAmount, {from: userAddress});
await expectRevert(
this.bondingCurve.purchase(userAddress, this.purchaseAmount, {from: userAddress}),
'BondingCurve: exceeds mint cap'
);
});
});
describe('Crossing Scale', function() {
beforeEach(async function() {
this.purchaseAmount = new BN('400000000');
Expand Down
11 changes: 11 additions & 0 deletions test/bondingcurve/EthBondingCurve.test.js
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Expand Up @@ -48,6 +48,8 @@ describe('EthBondingCurve', function () {
scale: '100000000000', buffer: '100', discount: '100', duration: this.incentiveDuration.toString(), incentive: this.incentiveAmount.toString(), pcvDeposits: [this.pcvDeposit1.address, this.pcvDeposit2.address], ratios: [9000, 1000]
});
await this.core.grantMinter(this.bondingCurve.address, {from: governorAddress});

await this.bondingCurve.setMintCap(this.scale.mul(new BN('10')), {from: governorAddress});
});

describe('Init', function() {
Expand Down Expand Up @@ -260,6 +262,15 @@ describe('EthBondingCurve', function () {
});
});

describe('Exceeding cap', function() {
it('reverts', async function() {
this.purchaseAmount = new BN('4000000000');
await expectRevert(
this.bondingCurve.purchase(userAddress, this.purchaseAmount, {from: userAddress, value: this.purchaseAmount}),
'BondingCurve: exceeds mint cap'
);
});
});
describe('Crossing Scale', function() {
beforeEach(async function() {
this.purchaseAmount = new BN('200000000');
Expand Down