adds forge test suite

.gitignore

@@ -5,4 +5,5 @@ node_modules
 coverage
 .env
 *.temp
-~/node_modules
+~/node_modules
+cache

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "forge/lib/forge-std"]
+	path = forge/lib/forge-std
+	url = https://github.com/foundry-rs/forge-std
+[submodule "forge/lib/openzeppelin-contracts"]
+	path = forge/lib/openzeppelin-contracts
+	url = https://github.com/OpenZeppelin/openzeppelin-contracts

.vscode/settings.json

@@ -1,11 +1,11 @@
 {
-    "editor.codeActionsOnSave": {
-        "source.addMissingImports": true,
-        "source.organizeImports": true,
-        "source.formatDocument": true,
-        "source.fixAll": true
-    },
-    "editor.showUnused": true,
-    "editor.formatOnPaste": true,
-    "editor.formatOnSave": true
+  "editor.codeActionsOnSave": {
+    "source.addMissingImports": true,
+    "source.fixAll": true,
+    "source.formatDocument": true,
+    "source.organizeImports": true
+  },
+  "editor.formatOnPaste": true,
+  "editor.formatOnSave": true,
+  "editor.showUnused": true
 }

forge/.github/workflows/test.yml

@@ -0,0 +1,34 @@
+name: test
+
+on: workflow_dispatch
+
+env:
+  FOUNDRY_PROFILE: ci
+
+jobs:
+  check:
+    strategy:
+      fail-fast: true
+
+    name: Foundry project
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Install Foundry
+        uses: foundry-rs/foundry-toolchain@v1
+        with:
+          version: nightly
+
+      - name: Run Forge build
+        run: |
+          forge --version
+          forge build --sizes
+        id: build
+
+      - name: Run Forge tests
+        run: |
+          forge test -vvv
+        id: test

forge/.gitignore

@@ -0,0 +1,14 @@
+# Compiler files
+cache/
+out/
+
+# Ignores development broadcast logs
+!/broadcast
+/broadcast/*/31337/
+/broadcast/**/dry-run/
+
+# Docs
+docs/
+
+# Dotenv file
+.env

forge/README.md

@@ -0,0 +1,66 @@
+## Foundry
+
+**Foundry is a blazing fast, portable and modular toolkit for Ethereum application development written in Rust.**
+
+Foundry consists of:
+
+-   **Forge**: Ethereum testing framework (like Truffle, Hardhat and DappTools).
+-   **Cast**: Swiss army knife for interacting with EVM smart contracts, sending transactions and getting chain data.
+-   **Anvil**: Local Ethereum node, akin to Ganache, Hardhat Network.
+-   **Chisel**: Fast, utilitarian, and verbose solidity REPL.
+
+## Documentation
+
+https://book.getfoundry.sh/
+
+## Usage
+
+### Build
+
+```shell
+$ forge build
+```
+
+### Test
+
+```shell
+$ forge test
+```
+
+### Format
+
+```shell
+$ forge fmt
+```
+
+### Gas Snapshots
+
+```shell
+$ forge snapshot
+```
+
+### Anvil
+
+```shell
+$ anvil
+```
+
+### Deploy
+
+```shell
+$ forge script script/Counter.s.sol:CounterScript --rpc-url <your_rpc_url> --private-key <your_private_key>
+```
+
+### Cast
+
+```shell
+$ cast <subcommand>
+```
+
+### Help
+
+```shell
+$ forge --help
+$ anvil --help
+$ cast --help
+```

forge/foundry.toml

@@ -0,0 +1,6 @@
+[profile.default]
+src = "src"
+out = "out"
+libs = ["lib"]
+
+# See more config options https://github.com/foundry-rs/foundry/blob/master/crates/config/README.md#all-options

forge/src/NegativeAmountHandler.sol

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import "openzeppelin-contracts/contracts/utils/cryptography/EIP712.sol";
+import "openzeppelin-contracts/contracts/utils/cryptography/ECDSA.sol";
+
+contract NegativeAmountHandler is EIP712 {
+    string private constant SIGNING_DOMAIN = "NegativeAmountHandler";
+    string private constant SIGNATURE_VERSION = "1";
+
+    struct Data {
+        int256 amount;
+        string message;
+    }
+
+    constructor() EIP712(SIGNING_DOMAIN, SIGNATURE_VERSION) {}
+
+    function verify(Data calldata data, bytes calldata signature) public view returns (bool) {
+        address signer = _verify(_hash(data), signature);
+        return signer == msg.sender;  // Ensure that the signer is the sender of the message
+    }
+
+    function _hash(Data calldata data) internal view returns (bytes32) {
+        return _hashTypedDataV4(keccak256(abi.encode(
+            keccak256("Data(int256 amount,string message)"),
+            data.amount,
+            keccak256(bytes(data.message))
+        )));
+    }
+
+    function _verify(bytes32 digest, bytes memory signature) internal view returns (address) {
+        return ECDSA.recover(digest, signature);
+    }
+}