feat: add ETH/USD price feed setter

packages/contracts/src/dollar/facets/UbiquityPoolFacet.sol

@@ -46,6 +46,15 @@ contract UbiquityPoolFacet is IUbiquityPool, Modifiers {
         return LibUbiquityPool.collateralUsdBalance();
     }
 
+    /// @inheritdoc IUbiquityPool
+    function ethUsdPriceFeedInformation()
+        external
+        view
+        returns (address, uint256)
+    {
+        return LibUbiquityPool.ethUsdPriceFeedInformation();
+    }
+
     /// @inheritdoc IUbiquityPool
     function freeCollateralBalance(
         uint256 collateralIndex
@@ -195,6 +204,17 @@ contract UbiquityPoolFacet is IUbiquityPool, Modifiers {
         LibUbiquityPool.setCollateralRatio(newCollateralRatio);
     }
 
+    /// @inheritdoc IUbiquityPool
+    function setEthUsdChainLinkPriceFeed(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    ) external onlyAdmin {
+        LibUbiquityPool.setEthUsdChainLinkPriceFeed(
+            newPriceFeedAddress,
+            newStalenessThreshold
+        );
+    }
+
     /// @inheritdoc IUbiquityPool
     function setFees(
         uint256 collateralIndex,

packages/contracts/src/dollar/interfaces/IUbiquityPool.sol

@@ -47,6 +47,15 @@ interface IUbiquityPool {
         view
         returns (uint256 balanceTally);
 
+    /**
+     * @notice Returns chainlink price feed information for ETH/USD pair
+     * @return Price feed address and staleness threshold in seconds
+     */
+    function ethUsdPriceFeedInformation()
+        external
+        view
+        returns (address, uint256);
+
     /**
      * @notice Returns free collateral balance (i.e. that can be borrowed by AMO minters)
      * @param collateralIndex collateral token index
@@ -214,6 +223,16 @@ interface IUbiquityPool {
      */
     function setCollateralRatio(uint256 newCollateralRatio) external;
 
+    /**
+     * @notice Sets chainlink params for ETH/USD price feed
+     * @param newPriceFeedAddress New chainlink price feed address for ETH/USD pair
+     * @param newStalenessThreshold New threshold in seconds when chainlink's ETH/USD price feed answer should be considered stale
+     */
+    function setEthUsdChainLinkPriceFeed(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    ) external;
+
     /**
      * @notice Sets mint and redeem fees, 1_000_000 = 100%
      * @param collateralIndex Collateral token index

packages/contracts/src/dollar/libraries/LibUbiquityPool.sol

@@ -92,6 +92,10 @@ library LibUbiquityPool {
         //====================================
         // Governance token pricing related
         //====================================
+        // chainlink price feed for ETH/USD pair
+        address ethUsdPriceFeedAddress;
+        // threshold in seconds when chainlink's ETH/USD price feed answer should be considered stale
+        uint256 ethUsdPriceFeedStalenessThreshold;
         // Curve's CurveTwocryptoOptimized contract for Governance/ETH pair
         address governanceEthPoolAddress;
     }
@@ -149,6 +153,11 @@ library LibUbiquityPool {
     event CollateralRatioSet(uint256 newCollateralRatio);
     /// @notice Emitted on enabling/disabling a particular collateral token
     event CollateralToggled(uint256 collateralIndex, bool newState);
+    /// @notice Emitted on setting chainlink's price feed for ETH/USD pair
+    event EthUsdPriceFeedSet(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    );
     /// @notice Emitted when fees are updated
     event FeesSet(
         uint256 collateralIndex,
@@ -298,6 +307,22 @@ library LibUbiquityPool {
         }
     }
 
+    /**
+     * @notice Returns chainlink price feed information for ETH/USD pair
+     * @return Price feed address and staleness threshold in seconds
+     */
+    function ethUsdPriceFeedInformation()
+        internal
+        view
+        returns (address, uint256)
+    {
+        UbiquityPoolStorage storage poolStorage = ubiquityPoolStorage();
+        return (
+            poolStorage.ethUsdPriceFeedAddress,
+            poolStorage.ethUsdPriceFeedStalenessThreshold
+        );
+    }
+
     /**
      * @notice Returns free collateral balance (i.e. that can be borrowed by AMO minters)
      * @param collateralIndex collateral token index
@@ -829,6 +854,23 @@ library LibUbiquityPool {
         emit CollateralRatioSet(newCollateralRatio);
     }
 
+    /**
+     * @notice Sets chainlink params for ETH/USD price feed
+     * @param newPriceFeedAddress New chainlink price feed address for ETH/USD pair
+     * @param newStalenessThreshold New threshold in seconds when chainlink's ETH/USD price feed answer should be considered stale
+     */
+    function setEthUsdChainLinkPriceFeed(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    ) internal {
+        UbiquityPoolStorage storage poolStorage = ubiquityPoolStorage();
+
+        poolStorage.ethUsdPriceFeedAddress = newPriceFeedAddress;
+        poolStorage.ethUsdPriceFeedStalenessThreshold = newStalenessThreshold;
+
+        emit EthUsdPriceFeedSet(newPriceFeedAddress, newStalenessThreshold);
+    }
+
     /**
      * @notice Sets mint and redeem fees, 1_000_000 = 100%
      * @param collateralIndex Collateral token index

packages/contracts/test/diamond/facets/UbiquityPoolFacet.t.sol

@@ -27,6 +27,7 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
     MockCurveStableSwapMetaNG curveDollarMetaPool;
     MockCurveTwocryptoOptimized curveGovernanceEthPool;
     MockERC20 curveTriPoolLpToken;
+    MockChainLinkFeed ethUsdPriceFeed;
     MockERC20 wethToken;
 
     address user = address(1);
@@ -42,6 +43,10 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
     event CollateralPriceSet(uint256 collateralIndex, uint256 newPrice);
     event CollateralRatioSet(uint256 newCollateralRatio);
     event CollateralToggled(uint256 collateralIndex, bool newState);
+    event EthUsdPriceFeedSet(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    );
     event FeesSet(
         uint256 collateralIndex,
         uint256 newMintFee,
@@ -67,6 +72,9 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
         // init collateral price feed
         collateralTokenPriceFeed = new MockChainLinkFeed();
 
+        // init ETH/USD price feed
+        ethUsdPriceFeed = new MockChainLinkFeed();
+
         // init WETH token
         wethToken = new MockERC20("WETH", "WETH", 18);
 
@@ -102,13 +110,28 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
             1 // answered in round
         );
 
+        // set ETH/USD price feed mock params
+        ethUsdPriceFeed.updateMockParams(
+            1, // round id
+            3000_00000000, // answer, 3000_00000000 = $3000 (8 decimals)
+            block.timestamp, // started at
+            block.timestamp, // updated at
+            1 // answered in round
+        );
+
         // set price feed for collateral token
         ubiquityPoolFacet.setCollateralChainLinkPriceFeed(
             address(collateralToken), // collateral token address
             address(collateralTokenPriceFeed), // price feed address
             1 days // price feed staleness threshold in seconds
         );
 
+        // set price feed for ETH/USD pair
+        ubiquityPoolFacet.setEthUsdChainLinkPriceFeed(
+            address(ethUsdPriceFeed), // price feed address
+            1 days // price feed staleness threshold in seconds
+        );
+
         // enable collateral at index 0
         ubiquityPoolFacet.toggleCollateral(0);
         // set mint and redeem fees
@@ -244,6 +267,15 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
         assertEq(balanceTally, 100e18);
     }
 
+    function testEthUsdPriceFeedInformation_ShouldReturnEthUsdPriceFeedInformation()
+        public
+    {
+        (address priceFeed, uint256 stalenessThreshold) = ubiquityPoolFacet
+            .ethUsdPriceFeedInformation();
+        assertEq(priceFeed, address(ethUsdPriceFeed));
+        assertEq(stalenessThreshold, 1 days);
+    }
+
     function testFreeCollateralBalance_ShouldReturnCollateralAmountAvailableForBorrowingByAmoMinters()
         public
     {
@@ -932,6 +964,37 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
         vm.stopPrank();
     }
 
+    function testSetEthUsdChainLinkPriceFeed_ShouldSetEthUsdChainLinkPriceFeed()
+        public
+    {
+        vm.startPrank(admin);
+
+        (
+            address oldPriceFeedAddress,
+            uint256 oldStalenessThreshold
+        ) = ubiquityPoolFacet.ethUsdPriceFeedInformation();
+        assertEq(oldPriceFeedAddress, address(ethUsdPriceFeed));
+        assertEq(oldStalenessThreshold, 1 days);
+
+        address newPriceFeedAddress = address(1);
+        uint256 newStalenessThreshold = 2 days;
+        vm.expectEmit(address(ubiquityPoolFacet));
+        emit EthUsdPriceFeedSet(newPriceFeedAddress, newStalenessThreshold);
+        ubiquityPoolFacet.setEthUsdChainLinkPriceFeed(
+            newPriceFeedAddress,
+            newStalenessThreshold
+        );
+
+        (
+            address updatedPriceFeedAddress,
+            uint256 updatedStalenessThreshold
+        ) = ubiquityPoolFacet.ethUsdPriceFeedInformation();
+        assertEq(updatedPriceFeedAddress, newPriceFeedAddress);
+        assertEq(updatedStalenessThreshold, newStalenessThreshold);
+
+        vm.stopPrank();
+    }
+
     function testSetFees_ShouldSetMintAndRedeemFees() public {
         vm.startPrank(admin);