Add DiamondCutFacet tests

Author: Corantin

pkg/contracts/test/DiamondCutFacet.t.sol

@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity ^0.8.19;
+
+import "forge-std/Test.sol";
+
+import {DiamondCutFacet} from "../src/diamonds/facets/DiamondCutFacet.sol";
+import {IDiamond} from "../src/diamonds/interfaces/IDiamond.sol";
+import {IDiamondCut} from "../src/diamonds/interfaces/IDiamondCut.sol";
+import {
+    LibDiamond,
+    NotContractOwner
+} from "../src/diamonds/libraries/LibDiamond.sol";
+
+contract DiamondCutHarness {
+    error FunctionDoesNotExist(bytes4 selector);
+
+    uint256 public initValue;
+
+    constructor(address _owner) {
+        LibDiamond.setContractOwner(_owner);
+    }
+
+    function rawCut(IDiamond.FacetCut[] memory _diamondCut) external {
+        LibDiamond.enforceIsContractOwner();
+        LibDiamond.diamondCut(_diamondCut, address(0), "");
+    }
+
+    function owner() external view returns (address) {
+        return LibDiamond.contractOwner();
+    }
+
+    fallback() external payable {
+        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
+        address facet = ds.facetAddressAndSelectorPosition[msg.sig].facetAddress;
+
+        if (facet == address(0)) {
+            revert FunctionDoesNotExist(msg.sig);
+        }
+
+        assembly {
+            calldatacopy(0, 0, calldatasize())
+            let result := delegatecall(gas(), facet, 0, calldatasize(), 0, 0)
+            returndatacopy(0, 0, returndatasize())
+            switch result
+            case 0 { revert(0, returndatasize()) }
+            default { return(0, returndatasize()) }
+        }
+    }
+
+    receive() external payable {}
+}
+
+contract SampleFacet {
+    function ping() external pure returns (uint256) {
+        return 7;
+    }
+}
+
+contract InitFacet {
+    uint256 public initValue;
+
+    function record(uint256 value) external {
+        initValue = value;
+    }
+}
+
+contract DiamondCutFacetTest is Test {
+    DiamondCutHarness private diamond;
+    DiamondCutFacet private cutFacet;
+    SampleFacet private sampleFacet;
+    InitFacet private initFacet;
+
+    address private owner;
+    address private attacker;
+
+    function setUp() public {
+        owner = makeAddr("owner");
+        attacker = makeAddr("attacker");
+
+        diamond = new DiamondCutHarness(owner);
+        cutFacet = new DiamondCutFacet();
+        sampleFacet = new SampleFacet();
+        initFacet = new InitFacet();
+
+        vm.prank(owner);
+        _installDiamondCutFacet();
+    }
+
+    function _installDiamondCutFacet() internal {
+        IDiamond.FacetCut[] memory cuts = new IDiamond.FacetCut[](1);
+        bytes4[] memory selectors = new bytes4[](1);
+        selectors[0] = DiamondCutFacet.diamondCut.selector;
+        cuts[0] = IDiamond.FacetCut({
+            facetAddress: address(cutFacet),
+            action: IDiamond.FacetCutAction.Add,
+            functionSelectors: selectors
+        });
+        diamond.rawCut(cuts);
+    }
+
+    function _singleCut(address facetAddress, bytes4 selector) internal pure returns (IDiamond.FacetCut[] memory cuts) {
+        cuts = new IDiamond.FacetCut[](1);
+        bytes4[] memory selectors = new bytes4[](1);
+        selectors[0] = selector;
+        cuts[0] = IDiamond.FacetCut({
+            facetAddress: facetAddress,
+            action: IDiamond.FacetCutAction.Add,
+            functionSelectors: selectors
+        });
+    }
+
+    function test_diamondCut_addsFacetAndRoutesCall() public {
+        IDiamond.FacetCut[] memory cuts = _singleCut(address(sampleFacet), SampleFacet.ping.selector);
+
+        vm.prank(owner);
+        DiamondCutFacet(address(diamond)).diamondCut(cuts, address(0), "");
+
+        assertEq(SampleFacet(address(diamond)).ping(), 7);
+    }
+
+    function test_diamondCut_revertsForNonOwner() public {
+        IDiamond.FacetCut[] memory cuts = _singleCut(address(sampleFacet), SampleFacet.ping.selector);
+
+        vm.prank(attacker);
+        vm.expectRevert(abi.encodeWithSelector(NotContractOwner.selector, attacker, owner));
+        DiamondCutFacet(address(diamond)).diamondCut(cuts, address(0), "");
+    }
+
+    function test_diamondCut_executesInitializerCall() public {
+        IDiamond.FacetCut[] memory cuts = _singleCut(address(sampleFacet), SampleFacet.ping.selector);
+
+        vm.prank(owner);
+        DiamondCutFacet(address(diamond)).diamondCut(
+            cuts,
+            address(initFacet),
+            abi.encodeWithSelector(InitFacet.record.selector, 42)
+        );
+
+        assertEq(diamond.initValue(), 42);
+        assertEq(SampleFacet(address(diamond)).ping(), 7);
+    }
+}