feat: validates constructor parameters (#9)

Closes EFI-448

Author: 0xItadaki

src/contracts/L2Resolver.sol

@@ -44,6 +44,13 @@ contract L2Resolver is IL2Resolver, IERC165 {
    * @param _parentNode The parent node namehash.
    */
   constructor(address _ensRegistry, address _nameWrapper, address _reverseAdmin, bytes32 _parentNode) {
+    if (
+      _ensRegistry == address(0) || _nameWrapper == address(0) || _reverseAdmin == address(0)
+        || _parentNode == bytes32(0)
+    ) {
+      revert AddressCannotBeZero();
+    }
+
     ENS_REGISTRY = IENS(_ensRegistry);
     NAME_WRAPPER = INameWrapper(_nameWrapper);
     REVERSE_ADMIN = _reverseAdmin;

src/interfaces/IL2Resolver.sol

@@ -30,6 +30,11 @@ interface IL2Resolver {
    */
   error NotAuthorized();
 
+  /**
+   * @notice Thrown when an address is zero.
+   */
+  error AddressCannotBeZero();
+
   /*///////////////////////////////////////////////////////////////
                             LOGIC
   //////////////////////////////////////////////////////////////*/

test/unit/L2Resolver.t.sol

@@ -34,7 +34,7 @@ contract UnitL2Resolver is Test {
     vm.etch(address(_nameWrapper), new bytes(0x1));
   }
 
-  function test_ConstructorWhenDeployingTheContract() external view {
+  function test_ConstructorWhenDeployingTheContractWithValidParameters() external view {
     // it sets the ENS registry address
     assertEq(address(_l2Resolver.ENS_REGISTRY()), _ensRegistry);
     // it sets the name wrapper address
@@ -45,6 +45,30 @@ contract UnitL2Resolver is Test {
     assertEq(_l2Resolver.PARENT_NODE(), _parentNodeNameHash);
   }
 
+  function test_ConstructorWhenDeployingTheContractWithZeroAddressENSRegistry() external {
+    // it reverts
+    vm.expectRevert(abi.encodeWithSelector(IL2Resolver.AddressCannotBeZero.selector));
+    new L2Resolver(address(0), _nameWrapper, _reverseAdmin, _parentNodeNameHash);
+  }
+
+  function test_ConstructorWhenDeployingTheContractWithZeroAddressNameWrapper() external {
+    // it reverts
+    vm.expectRevert(abi.encodeWithSelector(IL2Resolver.AddressCannotBeZero.selector));
+    new L2Resolver(_ensRegistry, address(0), _reverseAdmin, _parentNodeNameHash);
+  }
+
+  function test_ConstructorWhenDeployingTheContractWithZeroAddressReverseAdmin() external {
+    // it reverts
+    vm.expectRevert(abi.encodeWithSelector(IL2Resolver.AddressCannotBeZero.selector));
+    new L2Resolver(_ensRegistry, _nameWrapper, address(0), _parentNodeNameHash);
+  }
+
+  function test_ConstructorWhenDeployingTheContractWithZeroAddressParentNode() external {
+    // it reverts
+    vm.expectRevert(abi.encodeWithSelector(IL2Resolver.AddressCannotBeZero.selector));
+    new L2Resolver(_ensRegistry, _nameWrapper, _reverseAdmin, bytes32(0));
+  }
+
   modifier whenTheNodeIsTheReverseLookupNode() {
     _;
   }

test/unit/L2Resolver.tree

@@ -1,9 +1,18 @@
 UnitL2Resolver::constructor
-└── when deploying the contract
-    ├── it sets the ENS registry address
-    ├── it sets the name wrapper address
-    ├── it sets the reverse admin address
-    └── it sets the parent node namehash
+├── when deploying the contract with valid parameters
+│   ├── it sets the ENS registry address
+│   ├── it sets the name wrapper address
+│   ├── it sets the reverse admin address
+│   └── it sets the parent node namehash
+├── when deploying the contract with zero address ENS registry
+│   └── it reverts
+├── when deploying the contract with zero address Name Wrapper
+│   └── it reverts
+├── when deploying the contract with zero address reverse admin
+│   └── it reverts
+└── when deploying the contract with zero address parent node
+    └── it reverts
+
 
 UnitL2Resolver::setRecord
 ├── when the node is the reverse lookup node