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Fix the inversion order in OracleRef #829

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Merged
thomas-waite merged 4 commits into from
Jun 1, 2022
Merged

Fix the inversion order in OracleRef #829

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79b03d2
fix: invert the oracle price in correct order
thomas-waite May 17, 2022
ed59e5a
Merge branch 'develop' into fix-oracle-ref
thomas-waite Jun 1, 2022
7f13e22
docs: add detailed explanation for oracle price
thomas-waite Jun 1, 2022
6122655
Merge branch 'develop' into fix-oracle-ref
thomas-waite Jun 1, 2022
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9 changes: 5 additions & 4 deletions contracts/refs/OracleRef.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,11 @@ abstract contract OracleRef is IOracleRef, CoreRef {
}
require(valid, "OracleRef: oracle invalid");

// Invert the oracle price if necessary
if (doInvert) {
_peg = invert(_peg);
}

// Scale the oracle price by token decimals delta if necessary
uint256 scalingFactor;
if (decimalsNormalizer < 0) {
Expand All @@ -102,10 +107,6 @@ abstract contract OracleRef is IOracleRef, CoreRef {
_peg = _peg.mul(scalingFactor);
}

// Invert the oracle price if necessary
if (doInvert) {
_peg = invert(_peg);
}
return _peg;
}

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25 changes: 18 additions & 7 deletions test/unit/refs/OracleRef.test.ts
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Expand Up @@ -167,17 +167,28 @@ describe('OracleRef', () => {
);
});

it('positive decimal normalizer scales down', async function () {
await this.oracleRef.connect(impersonatedSigners[governorAddress]).setDecimalsNormalizer(4),
expect((await this.oracleRef.connect(impersonatedSigners[userAddress]).readOracle())[0]).to.be.equal(
'200000000000'
);
it('positive decimal normalizer scales up', async function () {
// Raw peg price: 500000000000000000000, 500e18
// Inversion is set to True by default in ReserveStabilizer
// Price after inversion = (1e18 * 1e18) / 500e18 = 0.2e16 = 2e15
// Scaling factor is set to 1e4. After applying scaling factor
// 2e15 * 1e4 = 2e19 = 20000000000000000000
await this.oracleRef.connect(impersonatedSigners[governorAddress]).setDecimalsNormalizer(4);

expect((await this.oracleRef.connect(impersonatedSigners[userAddress]).readOracle())[0]).to.be.equal(
'20000000000000000000'
);
});

it('negative decimal normalizer scales up', async function () {
it('negative decimal normalizer scales down', async function () {
// Raw peg price: 500000000000000000000, 500e18
// Inversion is set to True by default in ReserveStabilizer
// Price after inversion = (1e18 * 1e18) / 500e18 = 0.2e16 = 2e15
// Scaling factor is set to -1e4. After applying scaling factor
// 2e15 / 1e4 = 2e11 = 200000000000
await this.oracleRef.connect(impersonatedSigners[governorAddress]).setDecimalsNormalizer(-4),
expect((await this.oracleRef.connect(impersonatedSigners[userAddress]).readOracle())[0]).to.be.equal(
'20000000000000000000'
'200000000000'
);
});
});
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