Merge pull request #8 from joaobrunoah/rate-provider/binance-st-eth

Create a RateProvider to wBETH

contracts/BinanceBeaconEthRateProvider.sol

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+pragma solidity ^0.8.0;
+
+import "./interfaces/IRateProvider.sol";
+import "./interfaces/IwBETH.sol";
+
+/**
+ * @title Wrapped Binance Beacon ETH Rate Provider
+ * @notice Returns the value of wBETH in terms of ETH
+ */
+contract BinanceBeaconEthRateProvider is IRateProvider {
+    IwBETH public immutable wBETH;
+
+    constructor(IwBETH _wBETH) {
+        wBETH = _wBETH;
+    }
+
+    /**
+     * @return the value of wBETH in terms of ETH
+     */
+    function getRate() external view override returns (uint256) {
+        return wBETH.exchangeRate();
+    }
+}

contracts/interfaces/IwBETH.sol

@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-3.0
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+pragma solidity ^0.8.0;
+
+/**
+ * @title Token wrapper for Binance ETH staking deposits.
+ */
+interface IwBETH {
+    /**
+     * @notice Get amount of ETH for 1 wBETH
+     * @return Amount of ETH for 1 wBETH
+     */
+    function exchangeRate() external view returns (uint256);
+}