Fuzz Base64 and Base64URL (#4853)

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

test/utils/Base64.t.sol

@@ -6,27 +6,30 @@ import {Test} from "forge-std/Test.sol";
 
 import {Base64} from "@openzeppelin/contracts/utils/Base64.sol";
 
-/// NOTE: This test requires `ffi` to be enabled. It does not run in the CI
-/// environment given `ffi` is not recommended.
-/// See: https://github.com/foundry-rs/foundry/issues/6744
 contract Base64Test is Test {
     function testEncode(bytes memory input) external {
-        string memory output = Base64.encode(input);
-        assertEq(output, _base64Ffi(input, "encode"));
+        assertEq(Base64.encode(input), vm.toBase64(input));
     }
 
     function testEncodeURL(bytes memory input) external {
-        string memory output = Base64.encodeURL(input);
-        assertEq(output, _base64Ffi(input, "encodeURL"));
+        assertEq(Base64.encodeURL(input), _removePadding(vm.toBase64URL(input)));
     }
 
-    function _base64Ffi(bytes memory input, string memory fn) internal returns (string memory) {
-        string[] memory command = new string[](4);
-        command[0] = "bash";
-        command[1] = "scripts/tests/base64.sh";
-        command[2] = fn;
-        command[3] = vm.toString(input);
-        bytes memory retData = vm.ffi(command);
-        return string(retData);
+    function _removePadding(string memory inputStr) internal pure returns (string memory) {
+        bytes memory input = bytes(inputStr);
+        bytes memory output;
+
+        for (uint256 i = 0; i < input.length; ++i) {
+            if (input[input.length - i - 1] != 0x3d) {
+                output = new bytes(input.length - i);
+                break;
+            }
+        }
+
+        for (uint256 i = 0; i < output.length; ++i) {
+            output[i] = input[i];
+        }
+
+        return string(output);
     }
 }