add test file

MyToken.t.sol

@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+import {Test, console} from "forge-std/Test.sol";
+import {MyToken} from "../src/MyToken.sol";
+
+contract MyTokenTest is Test {
+	MyToken public myToken;
+	address public owner;
+	address public user;
+
+	function setUp() public {
+		owner = address(0x100);
+		user = address(0x101);
+
+		vm.deal(owner, 100 ether);
+		vm.deal(user, 100 ether);
+
+		vm.startPrank(owner);
+		myToken = new MyToken(1000);
+		vm.stopPrank();
+	}
+
+	function test_buyAndTransferTokens() public {
+		vm.startPrank(user); // User operations under here
+		uint ethAmount = 0.01 ether;
+		// uint ethAmount = 0.001 ether; // This will cause myToken.buyTokens() to revert
+
+		uint userBalanceBeforeBuy = myToken.balanceOf(user);
+		uint totalSupplyBeforeBuy = myToken.totalSupply();
+		console.log("User balance before buy:", userBalanceBeforeBuy);
+		console.log("Total supply before buy:", totalSupplyBeforeBuy);
+
+		uint expectedBalance = userBalanceBeforeBuy + ethAmount / myToken.tokenPrice();
+
+		myToken.buyTokens{value: ethAmount}();
+
+		uint userBalanceAfterBuy = myToken.balanceOf(user);
+		uint totalSupplyAfterBuy = myToken.totalSupply();
+		console.log("User balance after buy:", userBalanceAfterBuy);
+		console.log("Total supply after buy:", totalSupplyAfterBuy);
+
+		assert(userBalanceAfterBuy > userBalanceBeforeBuy);
+		assertEq(userBalanceAfterBuy, expectedBalance);
+		assertEq(totalSupplyAfterBuy, totalSupplyBeforeBuy + ethAmount / myToken.tokenPrice());
+
+		myToken.transfer(owner, userBalanceAfterBuy);
+		vm.stopPrank();
+	}
+}