feat: add stable/ETH setter

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

@@ -116,6 +116,15 @@ contract UbiquityPoolFacet is IUbiquityPool, Modifiers {
         return LibUbiquityPool.governanceEthPoolAddress();
     }
 
+    /// @inheritdoc IUbiquityPool
+    function stableEthPriceFeedInformation()
+        external
+        view
+        returns (address, uint256)
+    {
+        return LibUbiquityPool.stableEthPriceFeedInformation();
+    }
+
     //====================
     // Public functions
     //====================
@@ -293,6 +302,17 @@ contract UbiquityPoolFacet is IUbiquityPool, Modifiers {
         LibUbiquityPool.setRedemptionDelayBlocks(newRedemptionDelayBlocks);
     }
 
+    /// @inheritdoc IUbiquityPool
+    function setStableEthChainLinkPriceFeed(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    ) external onlyAdmin {
+        LibUbiquityPool.setStableEthChainLinkPriceFeed(
+            newPriceFeedAddress,
+            newStalenessThreshold
+        );
+    }
+
     /// @inheritdoc IUbiquityPool
     function toggleCollateral(uint256 collateralIndex) external onlyAdmin {
         LibUbiquityPool.toggleCollateral(collateralIndex);

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

@@ -121,6 +121,16 @@ interface IUbiquityPool {
      */
     function governanceEthPoolAddress() external view returns (address);
 
+    /**
+     * @notice Returns chainlink price feed information for stable/ETH pair
+     * @dev Here stable coin refers to the 1st coin in the Curve's stable/Dollar plain pool
+     * @return Price feed address and staleness threshold in seconds
+     */
+    function stableEthPriceFeedInformation()
+        external
+        view
+        returns (address, uint256);
+
     //====================
     // Public functions
     //====================
@@ -328,6 +338,16 @@ interface IUbiquityPool {
         uint256 newRedemptionDelayBlocks
     ) external;
 
+    /**
+     * @notice Sets chainlink params for stable/ETH price feed
+     * @param newPriceFeedAddress New chainlink price feed address for stable/ETH pair
+     * @param newStalenessThreshold New threshold in seconds when chainlink's stable/ETH price feed answer should be considered stale
+     */
+    function setStableEthChainLinkPriceFeed(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    ) external;
+
     /**
      * @notice Toggles (i.e. enables/disables) a particular collateral token
      * @param collateralIndex Collateral token index

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

@@ -103,6 +103,13 @@ library LibUbiquityPool {
         uint256 ethUsdPriceFeedStalenessThreshold;
         // Curve's CurveTwocryptoOptimized contract for Governance/ETH pair
         address governanceEthPoolAddress;
+        //================================
+        // Dollar token pricing related
+        //================================
+        // chainlink price feed for stable/ETH pair
+        address stableEthPriceFeedAddress;
+        // threshold in seconds when chainlink's stable/ETH price feed answer should be considered stale
+        uint256 stableEthPriceFeedStalenessThreshold;
     }
 
     /// @notice Struct used for detailed collateral information
@@ -182,6 +189,11 @@ library LibUbiquityPool {
     );
     /// @notice Emitted when a new redemption delay in blocks is set
     event RedemptionDelayBlocksSet(uint256 redemptionDelayBlocks);
+    /// @notice Emitted on setting chainlink's price feed for stable/ETH pair
+    event StableEthPriceFeedSet(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    );
 
     //=====================
     // Modifiers
@@ -467,6 +479,23 @@ library LibUbiquityPool {
         return poolStorage.governanceEthPoolAddress;
     }
 
+    /**
+     * @notice Returns chainlink price feed information for stable/ETH pair
+     * @dev Here stable coin refers to the 1st coin in the Curve's stable/Dollar plain pool
+     * @return Price feed address and staleness threshold in seconds
+     */
+    function stableEthPriceFeedInformation()
+        internal
+        view
+        returns (address, uint256)
+    {
+        UbiquityPoolStorage storage poolStorage = ubiquityPoolStorage();
+        return (
+            poolStorage.stableEthPriceFeedAddress,
+            poolStorage.stableEthPriceFeedStalenessThreshold
+        );
+    }
+
     //====================
     // Public functions
     //====================
@@ -1124,6 +1153,24 @@ library LibUbiquityPool {
         emit RedemptionDelayBlocksSet(newRedemptionDelayBlocks);
     }
 
+    /**
+     * @notice Sets chainlink params for stable/ETH price feed
+     * @param newPriceFeedAddress New chainlink price feed address for stable/ETH pair
+     * @param newStalenessThreshold New threshold in seconds when chainlink's stable/ETH price feed answer should be considered stale
+     */
+    function setStableEthChainLinkPriceFeed(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    ) internal {
+        UbiquityPoolStorage storage poolStorage = ubiquityPoolStorage();
+
+        poolStorage.stableEthPriceFeedAddress = newPriceFeedAddress;
+        poolStorage
+            .stableEthPriceFeedStalenessThreshold = newStalenessThreshold;
+
+        emit StableEthPriceFeedSet(newPriceFeedAddress, newStalenessThreshold);
+    }
+
     /**
      * @notice Toggles (i.e. enables/disables) a particular collateral token
      * @param collateralIndex Collateral token index

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

@@ -28,6 +28,7 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
     MockCurveTwocryptoOptimized curveGovernanceEthPool;
     MockERC20 curveTriPoolLpToken;
     MockChainLinkFeed ethUsdPriceFeed;
+    MockChainLinkFeed stableEthPriceFeed;
     MockERC20 wethToken;
 
     address user = address(1);
@@ -60,6 +61,10 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
         uint256 newRedeemPriceThreshold
     );
     event RedemptionDelayBlocksSet(uint256 redemptionDelayBlocks);
+    event StableEthPriceFeedSet(
+        address newPriceFeedAddress,
+        uint256 newStalenessThreshold
+    );
 
     function setUp() public override {
         super.setUp();
@@ -75,6 +80,9 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
         // init ETH/USD price feed
         ethUsdPriceFeed = new MockChainLinkFeed();
 
+        // init stable/ETH price feed
+        stableEthPriceFeed = new MockChainLinkFeed();
+
         // init WETH token
         wethToken = new MockERC20("WETH", "WETH", 18);
 
@@ -119,6 +127,15 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
             1 // answered in round
         );
 
+        // set stable/ETH price feed mock params
+        stableEthPriceFeed.updateMockParams(
+            1, // round id
+            330000000000000, // answer, 330000000000000 = 0.00033 ETH (18 decimals)
+            block.timestamp, // started at
+            block.timestamp, // updated at
+            1 // answered in round
+        );
+
         // set ETH/Governance price to 30k in Curve pool mock
         curveGovernanceEthPool.updateMockParams(30_000e18);
 
@@ -135,6 +152,12 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
             1 days // price feed staleness threshold in seconds
         );
 
+        // set price feed for stable/ETH pair
+        ubiquityPoolFacet.setStableEthChainLinkPriceFeed(
+            address(stableEthPriceFeed), // price feed address
+            1 days // price feed staleness threshold in seconds
+        );
+
         // enable collateral at index 0
         ubiquityPoolFacet.toggleCollateral(0);
         // set mint and redeem fees
@@ -455,6 +478,15 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
         assertEq(governanceEthPoolAddress, address(curveGovernanceEthPool));
     }
 
+    function testStableEthPriceFeedInformation_ShouldReturnStableEthPriceFeedInformation()
+        public
+    {
+        (address priceFeed, uint256 stalenessThreshold) = ubiquityPoolFacet
+            .stableEthPriceFeedInformation();
+        assertEq(priceFeed, address(stableEthPriceFeed));
+        assertEq(stalenessThreshold, 1 days);
+    }
+
     //====================
     // Public functions
     //====================
@@ -1509,6 +1541,37 @@ contract UbiquityPoolFacetTest is DiamondTestSetup {
         vm.stopPrank();
     }
 
+    function testSetStableEthChainLinkPriceFeed_ShouldSetStableEthChainLinkPriceFeed()
+        public
+    {
+        vm.startPrank(admin);
+
+        (
+            address oldPriceFeedAddress,
+            uint256 oldStalenessThreshold
+        ) = ubiquityPoolFacet.stableEthPriceFeedInformation();
+        assertEq(oldPriceFeedAddress, address(stableEthPriceFeed));
+        assertEq(oldStalenessThreshold, 1 days);
+
+        address newPriceFeedAddress = address(1);
+        uint256 newStalenessThreshold = 2 days;
+        vm.expectEmit(address(ubiquityPoolFacet));
+        emit StableEthPriceFeedSet(newPriceFeedAddress, newStalenessThreshold);
+        ubiquityPoolFacet.setStableEthChainLinkPriceFeed(
+            newPriceFeedAddress,
+            newStalenessThreshold
+        );
+
+        (
+            address updatedPriceFeedAddress,
+            uint256 updatedStalenessThreshold
+        ) = ubiquityPoolFacet.stableEthPriceFeedInformation();
+        assertEq(updatedPriceFeedAddress, newPriceFeedAddress);
+        assertEq(updatedStalenessThreshold, newStalenessThreshold);
+
+        vm.stopPrank();
+    }
+
     function testToggleCollateral_ShouldToggleCollateral() public {
         vm.startPrank(admin);