add multicalltest contract

.prettierignore

@@ -7,3 +7,4 @@ src/lib/abi/**
 .nyc_output
 out/**
 lib/**
+src/mocks/MultiCallTest.sol

src/mocks/MultiCallTest.sol

@@ -0,0 +1,117 @@
+// Copyright 2024, Offchain Labs, Inc.
+// For license information, see https://github.com/nitro/blob/master/LICENSE
+// SPDX-License-Identifier: BUSL-1.1
+
+pragma solidity ^0.8.0;
+
+/*
+ * this contract is the solidity equivalent of stylus multicall test contract
+ * it should only be used for stylus tests, and it ignores good solidity good practices
+ */
+
+contract MultiCallTest {
+    event Called(address addr, uint8 count, bool success, bytes returnData);
+    event Storage(bytes32 slot, bytes32 data, bool write);
+
+    function getBE(bytes calldata data, uint8 numBytes) internal pure returns (uint256) {
+        uint256 res = 0;
+        for (uint8 i = 0; i < numBytes; i++) {
+            res = res << 8;
+            res = res | uint8(data[i]);
+        }
+        return res;
+    }
+
+    // solhint-disable no-complex-fallback
+    // solhint-disable reason-string
+    // solhint-disable avoid-low-level-calls
+    // solhint-disable-next-line prettier/prettier
+    fallback(bytes calldata input) external payable returns (bytes memory) {
+        require(input.length > 0);
+        uint8 count = uint8(input[0]);
+        input = input[1:];
+
+        // combined output of all calls
+        bytes memory output;
+
+        for (uint8 i = 0; i < count; i++) {
+            uint32 length = uint32(getBE(input, 4));
+            input = input[4:];
+
+            bytes calldata curr = input[:length];
+            input = input[length:];
+
+            uint8 kind = uint8(curr[0]);
+            curr = curr[1:];
+
+            if (kind & 0xf0 == 0x0)  {
+                // call
+                uint256 value;
+                if (kind & 0x3 == 0) {
+                    value = getBE(curr, 32);
+                    curr = curr[32:];
+                }
+
+                address addr = address(bytes20(curr[:20]));
+                bytes calldata data = curr[20:];
+                bytes memory out;
+                bool success;
+
+                if (kind & 0x3 == 0) {
+                    (success, out) = addr.call{value: value}(data);
+                } else if (kind & 0x3 == 1) {
+                    (success, out) = addr.delegatecall(data);
+                } else if (kind & 0x3 == 2) {
+                    (success, out) = addr.staticcall(data);
+                } else {
+                    revert("unknown call kind");
+                }
+                if (!success) {
+                    if (kind & 0x4 == 0) {
+                        uint256 len = out.length;
+                        if (len > 0) {
+                            assembly {
+                                revert(add(out, 32), len)
+                            }
+                        } else {
+                            revert();
+                        }
+                    }
+                    out = "";
+                }
+                if (kind & 0x8 != 0) {
+                    emit Called(addr, count, success, out);
+                }
+                output = bytes.concat(output, out);
+            } else if (kind & 0xf0 == 0x10)  {
+                // storage
+                bytes32 slot = bytes32(curr[:32]);
+                curr = curr[32:];
+                bytes32 data;
+                bool write;
+                if (kind & 0x3 == 0) {
+                    data = bytes32(curr[:32]);
+                    write = true;
+                    assembly {
+                        sstore(slot, data)
+                    }
+                } else if (kind & 0x3 == 1){
+                    write = false;
+                    assembly {
+                        data := sload(slot)
+                    }
+                    output = bytes.concat(output, data);
+                } else {
+                    revert("unknown storage kind");
+                }
+                if (kind & 0x8 != 0) {
+                    emit Storage(slot, data, write);
+                }
+            } else {
+                revert("unknown command");
+            }
+        }
+
+        return output;
+    }
+}