Add eth_call with account state overrides for bytecode

src/protocols/EthJsonRPC.sol

@@ -13,6 +13,11 @@ contract EthJsonRPC {
 
     string endpoint;
 
+    struct AccountOverride {
+        address addr;
+        bytes code;
+    }
+
     constructor(string memory _endpoint) {
         endpoint = _endpoint;
     }
@@ -65,6 +70,44 @@ contract EthJsonRPC {
         return result;
     }
 
+    /// @notice call a contract function with a state override.
+    /// @param to the address of the contract.
+    /// @param data the data of the function.
+    /// @param accountOverride the state override.
+    /// @return the result of the function call.
+    function call(address to, bytes memory data, AccountOverride[] memory accountOverride)
+        public
+        returns (bytes memory)
+    {
+        bytes memory body = abi.encodePacked(
+            '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"',
+            LibString.toHexStringChecksummed(to),
+            '","data":"',
+            LibString.toHexString(data),
+            '"},"latest",{'
+        );
+
+        for (uint256 i = 0; i < accountOverride.length; i++) {
+            body = abi.encodePacked(
+                body,
+                '"',
+                LibString.toHexStringChecksummed(accountOverride[i].addr),
+                '": {"code": "',
+                LibString.toHexString(accountOverride[i].code),
+                '"}'
+            );
+            if (i < accountOverride.length - 1) {
+                body = abi.encodePacked(body, ",");
+            }
+        }
+        body = abi.encodePacked(body, '}],"id":1}');
+
+        JSONParserLib.Item memory item = doRequest(string(body));
+        bytes memory result = HexStrings.fromHexString(_stripQuotesAndPrefix(item.value()));
+
+        return result;
+    }
+
     function doRequest(string memory body) public returns (JSONParserLib.Item memory) {
         Suave.HttpRequest memory request;
         request.method = "POST";

test/protocols/EthJsonRPC.t.sol

@@ -26,8 +26,27 @@ contract EthJsonRPCTest is Test, SuaveEnabled {
 
         bytes memory data = abi.encodeWithSignature("get_deposit_count()");
         bytes memory result = ethjsonrpc.call(address(0x00000000219ab540356cBB839Cbe05303d7705Fa), data);
+        uint256 resultUint = abi.decode(result, (uint256));
 
-        require(result.length > 0, "result is empty");
+        require(resultUint > 0, "result is empty");
+    }
+
+    function testEthJsonRPCCallWithOverrides() public {
+        EthJsonRPC ethjsonrpc = getEthJsonRPC();
+
+        EthJsonRPC.AccountOverride memory accountOverride = EthJsonRPC.AccountOverride({
+            addr: address(0x00000000219ab540356cBB839Cbe05303d7705Fa),
+            code: type(TestOverrideContract).runtimeCode
+        });
+
+        EthJsonRPC.AccountOverride[] memory acco = new EthJsonRPC.AccountOverride[](1);
+        acco[0] = accountOverride;
+
+        bytes memory data = abi.encodeWithSignature("get_deposit_count()");
+        bytes memory result = ethjsonrpc.call(address(0x00000000219ab540356cBB839Cbe05303d7705Fa), data, acco);
+        uint256 resultUint = abi.decode(result, (uint256));
+
+        require(resultUint == 10, "result is empty");
     }
 
     function getEthJsonRPC() public returns (EthJsonRPC ethjsonrpc) {
@@ -38,3 +57,9 @@ contract EthJsonRPCTest is Test, SuaveEnabled {
         }
     }
 }
+
+contract TestOverrideContract {
+    function get_deposit_count() public pure returns (uint256) {
+        return 10;
+    }
+}