adding more logs to debug 0 price

Author: haider-rs

src/oracle/IOracle.sol

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: MIT
+// Analog's Contracts (last updated v0.1.0) (src/Gateway.sol)
+
+pragma solidity >=0.8.0;
+
+interface IOracle {
+    function getNativePrice() external view returns (uint256);
+}

src/oracle/UniswapV2Oracle.sol

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+// SPDX-License-Identifier: MIT
+// Analog's Contracts (last updated v0.1.0) (src/Gateway.sol)
+
+pragma solidity >=0.8.0;
+
+import "src/oracle/IOracle.sol";
+import {Test, console} from "forge-std/Test.sol";
+
+interface IUniswapV2Factory {
+    function getPair(address tokenA, address tokenB) external view returns (address pair);
+}
+
+interface IUniswapV2Pair {
+    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
+    function token0() external view returns (address);
+    function token1() external view returns (address);
+}
+
+interface IERC20 {
+    function decimals() external view returns (uint8);
+}
+
+contract UniswapV2Oracle is IOracle {
+    address public immutable factory;
+    address public immutable WETH;
+    address public immutable USDT;
+
+    constructor(address _factory, address _weth, address _usdt) {
+        factory = _factory;
+        WETH = _weth;
+        USDT = _usdt;
+    }
+
+    function getNativePrice() external view override returns (uint256) {
+        return getTokenPrice(WETH, USDT, 1 ether);
+    }
+
+    function getTokenPrice(address tokenA, address tokenB, uint256 amount) public view returns (uint256) {
+        address pairAddress = IUniswapV2Factory(factory).getPair(tokenA, tokenB);
+        console.log("pair address: ", pairAddress);
+        require(pairAddress != address(0), "Pair does not exist");
+
+        IUniswapV2Pair pair = IUniswapV2Pair(pairAddress);
+
+        (uint112 reserve0, uint112 reserve1,) = pair.getReserves();
+        require(reserve0 > 0 && reserve1 > 0, "Insufficient liquidity");
+        console.log("reserve0 is, ", reserve0);
+        console.log("reserve1 is, ", reserve1);
+
+        address token0 = pair.token0();
+        // address token1 = pair.token1();
+
+        uint256 reserveA;
+        uint256 reserveB;
+
+        if (tokenA == token0) {
+            reserveA = uint256(reserve0);
+            reserveB = uint256(reserve1);
+        } else {
+            reserveA = uint256(reserve1);
+            reserveB = uint256(reserve0);
+        }
+
+        uint8 decimalsA = IERC20(tokenA).decimals();
+        console.log("decimal a", decimalsA);
+        uint8 decimalsB = IERC20(tokenB).decimals();
+        console.log("decimal b", decimalsB);
+
+        uint256 price = (amount * reserveB * (10 ** decimalsB)) / (reserveA * (10 ** decimalsA));
+        console.log("price calculated is", price);
+
+        return price;
+    }
+
+    function getPairAddress(address tokenA, address tokenB) external view returns (address) {
+        return IUniswapV2Factory(factory).getPair(tokenA, tokenB);
+    }
+}

test/UniswapV2Oracle.t.sol

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+// SPDX-License-Identifier: MIT
+// Analog's Contracts (last updated v0.1.0) (src/Gateway.sol)
+
+pragma solidity >=0.8.0;
+
+import {Test, console} from "forge-std/Test.sol";
+import {UniswapV2Oracle} from "src/oracle/UniswapV2Oracle.sol";
+
+contract UniswapV2OracleTest is Test {
+    UniswapV2Oracle oracle;
+    // IUniswapV2Factory factory;
+    // IUniswapV2Pair pair;
+
+    address constant WETH = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
+    address constant USDT = 0xdAC17F958D2ee523a2206206994597C13D831ec7;
+    address constant FACTORY = 0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f;
+
+    function setUp() public {
+        vm.createSelectFork({urlOrAlias: "https://eth.meowrpc.com"});
+        oracle = new UniswapV2Oracle(FACTORY, WETH, USDT);
+    }
+
+    function testGetNativePrice() public view {
+        uint256 price = oracle.getNativePrice();
+        console.log("WETH/USDT Price:", price);
+    }
+}