port ctoken oracle

contracts/protocol/integration/oracles/CTokenOracle.sol

@@ -0,0 +1,92 @@
+/*
+    Copyright 2021 Set Labs Inc.
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+pragma solidity 0.6.10;
+
+import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
+
+import { PreciseUnitMath } from "../../../lib/PreciseUnitMath.sol";
+import { ICErc20 } from "../../../interfaces/external/ICErc20.sol";
+import { IOracle } from "../../../interfaces/IOracle.sol";
+
+
+/**
+ * @title CTokenOracle
+ * @author Set Protocol
+ *
+ * Oracle built to return cToken price by multiplying the underlying asset price by Compound's stored exchange rate
+ */
+contract CTokenOracle is IOracle {
+    using SafeMath for uint256;
+    using PreciseUnitMath for uint256;
+
+    /* ============ State Variables ============ */
+    ICErc20 public immutable cToken;
+    IOracle public immutable underlyingOracle; // Underlying token oracle
+    string public dataDescription;
+
+    // CToken Full Unit
+    uint256 public immutable cTokenFullUnit;
+
+    // Underlying Asset Full Unit
+    uint256 public immutable underlyingFullUnit;
+
+    /* ============ Constructor ============ */
+
+    /*
+     * @param  _cToken             The address of Compound Token
+     * @param  _underlyingOracle   The address of the underlying oracle
+     * @param  _cTokenFullUnit     The full unit of the Compound Token
+     * @param  _underlyingFullUnit The full unit of the underlying asset
+     * @param  _dataDescription    Human readable description of oracle
+     */
+    constructor(
+        ICErc20 _cToken,
+        IOracle _underlyingOracle,
+        uint256 _cTokenFullUnit,
+        uint256 _underlyingFullUnit,
+        string memory _dataDescription
+    )
+        public
+    {
+        cToken = _cToken;
+        cTokenFullUnit = _cTokenFullUnit;
+        underlyingFullUnit = _underlyingFullUnit;
+        underlyingOracle = _underlyingOracle;
+        dataDescription = _dataDescription;
+    }
+
+    /**
+     * Returns the price value of a full cToken denominated in underlyingOracle value
+     * The underlying oracle is assumed to return a price of 18 decimal
+     * for a single full token of the underlying asset. The derived price
+     * of the cToken is then the price of a unit of underlying multiplied
+     * by the exchangeRate, adjusted for decimal differences, and descaled.
+     */
+    function read()
+        external
+        override
+        view
+        returns (uint256)
+    {
+        // Retrieve the price of the underlying
+        uint256 underlyingPrice = underlyingOracle.read();
+
+        // Retrieve cToken underlying to cToken stored conversion rate
+        uint256 conversionRate = cToken.exchangeRateStored();
+
+        // Price of underlying is the price value / Token * conversion / scaling factor
+        // Values need to be converted based on full unit quantities
+        return underlyingPrice.preciseMul(conversionRate).mul(cTokenFullUnit).div(underlyingFullUnit);
+    }
+}

test/integration/oracles/cTokenOracle.spec.ts

@@ -0,0 +1,155 @@
+import "module-alias/register";
+import { BigNumber } from "@ethersproject/bignumber";
+
+import { Address } from "@utils/types";
+import { Account } from "@utils/test/types";
+import { CERc20 } from "@utils/contracts/compound";
+import { OracleMock, CTokenOracle } from "@utils/contracts";
+import DeployHelper from "@utils/deploys";
+
+import {
+  ether
+} from "@utils/index";
+import {
+  getAccounts,
+  getWaffleExpect,
+  getSystemFixture,
+  getCompoundFixture,
+  addSnapshotBeforeRestoreAfterEach,
+} from "@utils/test/index";
+import { CompoundFixture, SystemFixture } from "@utils/fixtures";
+
+const expect = getWaffleExpect();
+
+describe("CTokenOracle", () => {
+  let owner: Account;
+  let deployer: DeployHelper;
+  let setup: SystemFixture;
+
+  let compoundSetup: CompoundFixture;
+  let cDai: CERc20;
+  let exchangeRate: BigNumber;
+  let daiUsdcOracle: OracleMock;
+  let cDaiOracle: CTokenOracle;
+  let cDaiFullUnit: BigNumber;
+  let daiFullUnit: BigNumber;
+
+  before(async () => {
+    [
+      owner,
+    ] = await getAccounts();
+
+    // System setup
+    deployer = new DeployHelper(owner.wallet);
+    setup = getSystemFixture(owner.address);
+    await setup.initialize();
+
+    // Compound setup
+    compoundSetup = getCompoundFixture(owner.address);
+    await compoundSetup.initialize();
+
+    exchangeRate = ether(0.5);
+
+    cDai = await compoundSetup.createAndEnableCToken(
+      setup.dai.address,
+      exchangeRate,
+      compoundSetup.comptroller.address,
+      compoundSetup.interestRateModel.address,
+      "Compound DAI",
+      "cDAI",
+      8,
+      ether(0.75), // 75% collateral factor
+      ether(1)
+    );
+
+    daiUsdcOracle = await deployer.mocks.deployOracleMock(ether(1));
+    cDaiFullUnit = BigNumber.from("100000000");
+    daiFullUnit = BigNumber.from("1000000000000000000");
+    cDaiOracle = await deployer.oracles.deployCTokenOracle(
+      cDai.address,
+      daiUsdcOracle.address,
+      cDaiFullUnit,
+      daiFullUnit,
+      "cDAI Oracle"
+    );
+
+  });
+
+  addSnapshotBeforeRestoreAfterEach();
+
+  describe("#constructor", async () => {
+    let subjectCToken: Address;
+    let subjectUnderlyingOracle: Address;
+    let subjectCTokenFullUnit: BigNumber;
+    let subjectUnderlyingFullUnit: BigNumber;
+    let subjectDataDescription: string;
+
+    before(async () => {
+      subjectCToken = cDai.address;
+      subjectCTokenFullUnit = BigNumber.from("100000000");
+      subjectUnderlyingFullUnit = BigNumber.from("1000000000000000000");
+      subjectUnderlyingOracle = daiUsdcOracle.address;
+      subjectDataDescription = "cDAI Oracle";
+    });
+
+    async function subject(): Promise<CTokenOracle> {
+      return deployer.oracles.deployCTokenOracle(
+        subjectCToken,
+        subjectUnderlyingOracle,
+        subjectCTokenFullUnit,
+        subjectUnderlyingFullUnit,
+        subjectDataDescription
+      );
+    }
+
+    it("sets the correct cToken address", async () => {
+      const cTokenOracle = await subject();
+      const cTokenAddress = await cTokenOracle.cToken();
+      expect(cTokenAddress).to.equal(subjectCToken);
+    });
+
+    it("sets the correct cToken full unit", async () => {
+      const cTokenOracle = await subject();
+      const cTokenFullUnit = await cTokenOracle.cTokenFullUnit();
+      expect(cTokenFullUnit).to.eq(subjectCTokenFullUnit);
+    });
+
+    it("sets the correct underlying full unit", async () => {
+      const cTokenOracle = await subject();
+      const underlyingFullUnit = await cTokenOracle.underlyingFullUnit();
+      expect(underlyingFullUnit).to.eq(subjectUnderlyingFullUnit);
+    });
+
+    it("sets the correct underlying oracle address", async () => {
+      const cTokenOracle = await subject();
+      const underlyingOracleAddress = await cTokenOracle.underlyingOracle();
+      expect(underlyingOracleAddress).to.eq(subjectUnderlyingOracle);
+    });
+
+    it("sets the correct data description", async () => {
+      const cTokenOracle = await subject();
+      const actualDataDescription = await cTokenOracle.dataDescription();
+      expect(actualDataDescription).to.eq(subjectDataDescription);
+    });
+
+  });
+
+
+  describe("#read", async () => {
+
+    async function subject(): Promise<BigNumber> {
+      return cDaiOracle.read();
+    }
+
+    it("returns the correct cTokenValue", async () => {
+      const result = await subject();
+      const expectedResult = ether(1)
+                              .mul(exchangeRate)
+                              .mul(cDaiFullUnit)
+                              .div(daiFullUnit)
+                              .div(ether(1));
+
+      expect(result).to.eq(expectedResult);
+    });
+  });
+});

utils/contracts/index.ts

@@ -49,6 +49,7 @@ export { OneInchExchangeAdapter } from "../../typechain/OneInchExchangeAdapter";
 export { OneInchExchangeMock } from "../../typechain/OneInchExchangeMock";
 export { OracleAdapterMock } from "../../typechain/OracleAdapterMock";
 export { OracleMock } from "../../typechain/OracleMock";
+export { CTokenOracle } from "../../typechain/CTokenOracle";
 export { PositionMock } from "../../typechain/PositionMock";
 export { PreciseUnitMathMock } from "../../typechain/PreciseUnitMathMock";
 export { PriceOracle } from "../../typechain/PriceOracle";

utils/deploys/deployOracles.ts

@@ -0,0 +1,27 @@
+import { Signer } from "ethers";
+import { Address } from "../types";
+import { BigNumber } from "@ethersproject/bignumber";
+
+import {
+  CTokenOracle,
+} from "../contracts";
+
+import { CTokenOracle__factory } from "../../typechain/factories/CTokenOracle__factory";
+
+export default class DeployOracles {
+  private _deployerSigner: Signer;
+
+  constructor(deployerSigner: Signer) {
+    this._deployerSigner = deployerSigner;
+  }
+
+  public async deployCTokenOracle(
+    cToken: Address,
+    underlyingOracle: Address,
+    cTokenFullUnit: BigNumber,
+    underlyingFullUnit: BigNumber,
+    dataDescription: string): Promise<CTokenOracle> {
+    return await new CTokenOracle__factory(this._deployerSigner)
+      .deploy(cToken, underlyingOracle, cTokenFullUnit, underlyingFullUnit, dataDescription);
+  }
+}

utils/deploys/index.ts

@@ -8,6 +8,7 @@ import DeployExternalContracts from "./deployExternal";
 import DeployAdapters from "./deployAdapters";
 import DeployViewers from "./deployViewers";
 import DeployProduct from "./deployProduct";
+import DeployOracles from "./deployOracles";
 
 export default class DeployHelper {
   public libraries: DeployLibraries;
@@ -18,6 +19,7 @@ export default class DeployHelper {
   public adapters: DeployAdapters;
   public viewers: DeployViewers;
   public product: DeployProduct;
+  public oracles: DeployOracles;
 
   constructor(deployerSigner: Signer) {
     this.libraries = new DeployLibraries(deployerSigner);
@@ -28,7 +30,6 @@ export default class DeployHelper {
     this.adapters = new DeployAdapters(deployerSigner);
     this.viewers = new DeployViewers(deployerSigner);
     this.product = new DeployProduct(deployerSigner);
+    this.oracles = new DeployOracles(deployerSigner);
   }
 }
-
-