feat: introduce htsSetup wrapper function (#138)

Signed-off-by: Luis Mastrangelo <luis@swirldslabs.com>

src/htsSetup.sol

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: Apache-2.0
+pragma solidity ^0.8.0;
+
+import {Vm} from "forge-std/Vm.sol";
+
+import {HtsSystemContractJson, HTS_ADDRESS} from "./HtsSystemContractJson.sol";
+import {MirrorNode} from "./MirrorNode.sol";
+import {MirrorNodeFFI} from "./MirrorNodeFFI.sol";
+
+Vm constant vm = Vm(address(uint160(uint256(keccak256("hevm cheat code")))));
+
+/**
+ * @notice Sets up the HTS emulation contract.
+ * The HTS emulation contract will be deployed at `0x167` address using `vm.etch`.
+ *
+ * Remember to enable [ffi](https://book.getfoundry.sh/cheatcodes/ffi)
+ * in your Foundry project to use HTS contract in your tests.
+ * You can do this by adding the following lines to your `.toml` file
+ *
+ * ```toml
+ * [profile.default]
+ * ffi = true
+ * ```
+ *
+ * Alternatively, you can include the `--ffi` flag when running `forge`.
+ *
+ * This is necessary because our library uses `ffi` to fetch remote state from the Mirror Node.
+ * 
+ * > DISCLAIMER
+ * > The HTS emulation contract **SHOULD BE ONLY** used to ease development workflow when working with Hedera Tokens.
+ * > The HTS emulation contract **DOES NOT** replicate Hedera Token Services fully.
+ * > That is, behavior might differ when switching from local development to a real Hedera network.
+ * > Always test your contracts against a real Hedera network before launching your contracts.
+ */
+function htsSetup() {
+    htsSetup(new MirrorNodeFFI());
+}
+
+function htsSetup(MirrorNode mirrorNode) {
+    __deployCodeTo("HtsSystemContractJson.sol", HTS_ADDRESS);
+    HtsSystemContractJson(HTS_ADDRESS).setMirrorNodeProvider(mirrorNode);
+    vm.allowCheatcodes(HTS_ADDRESS);
+}
+
+/**
+ * @dev Taken from `StdCheats.sol:deployCodeTo`.
+ * This is to avoid inheriting from `StdCheats`, and such simplifying usage.
+ */
+function __deployCodeTo(string memory what, address where) {
+    bytes memory creationCode = vm.getCode(what);
+    vm.etch(where, creationCode);
+    (bool success, bytes memory runtimeBytecode) = where.call("");
+    require(success, "__deployCodeTo(string,address): Failed to create runtime bytecode.");
+    vm.etch(where, runtimeBytecode);
+}

test/lib/TestSetup.sol

@@ -2,17 +2,12 @@
 pragma solidity ^0.8.0;
 
 import {console} from "forge-std/console.sol";
-import {StdCheats} from "forge-std/StdCheats.sol";
-import {Vm} from "forge-std/Vm.sol";
 
-import {HtsSystemContractJson, HTS_ADDRESS} from "../../src/HtsSystemContractJson.sol";
-import {MirrorNodeFFI} from "../../src/MirrorNodeFFI.sol";
+import {htsSetup} from "../../src/htsSetup.sol";
+import {HTS_ADDRESS} from "../../src/HtsSystemContractJson.sol";
 import {MirrorNodeMock} from "./MirrorNodeMock.sol";
 
-abstract contract TestSetup is StdCheats {
-    // `vm` is private in StdCheats, so we duplicate it here
-    Vm private constant vm = Vm(address(uint160(uint256(keccak256("hevm cheat code")))));
-
+abstract contract TestSetup {
     /**
      * https://hashscan.io/testnet/token/0.0.429274
      * https://testnet.mirrornode.hedera.com/api/v1/tokens/0.0.429274
@@ -59,25 +54,17 @@ abstract contract TestSetup is StdCheats {
     function setUpMockStorageForNonFork() internal {
         if (HTS_ADDRESS.code.length == 0) {
             console.log("HTS code length is 0, non-fork test, code and data provided locally");
-
-            deployCodeTo("HtsSystemContractJson.sol", HTS_ADDRESS);
             MirrorNodeMock mirrorNode = new MirrorNodeMock();
             mirrorNode.deployHIP719Proxy(USDC, "USDC");
             mirrorNode.deployHIP719Proxy(MFCT, "MFCT");
-            HtsSystemContractJson(HTS_ADDRESS).setMirrorNodeProvider(mirrorNode);
-            vm.allowCheatcodes(HTS_ADDRESS);
-
+            htsSetup(mirrorNode);
             testMode = TestMode.NonFork;
         } else if (HTS_ADDRESS.code.length == 1) {
             console.log("HTS code length is 1, forking from a remote Hedera network, HTS/FFI code with Mirror Node backend is deployed here");
-            deployCodeTo("HtsSystemContractJson.sol", HTS_ADDRESS);
-            HtsSystemContractJson(HTS_ADDRESS).setMirrorNodeProvider(new MirrorNodeFFI());
-            vm.allowCheatcodes(HTS_ADDRESS);
-
+            htsSetup();
             testMode = TestMode.FFI;
         } else {
             console.log("HTS code length is greater than 1 (%d), HTS code comes from forked network", HTS_ADDRESS.code.length);
-
             testMode = TestMode.JSON_RPC;
         }
     }