feat: invariant target interfaces (#445)

src/StdInvariant.sol

@@ -9,6 +9,11 @@ abstract contract StdInvariant {
         bytes4[] selectors;
     }
 
+    struct FuzzInterface {
+        address addr;
+        string[] artifacts;
+    }
+
     address[] private _excludedContracts;
     address[] private _excludedSenders;
     address[] private _targetedContracts;
@@ -20,6 +25,8 @@ abstract contract StdInvariant {
     FuzzSelector[] private _targetedArtifactSelectors;
     FuzzSelector[] private _targetedSelectors;
 
+    FuzzInterface[] private _targetedInterfaces;
+
     // Functions for users:
     // These are intended to be called in tests.
 
@@ -55,6 +62,10 @@ abstract contract StdInvariant {
         _targetedSenders.push(newTargetedSender_);
     }
 
+    function targetInterface(FuzzInterface memory newTargetedInterface_) internal {
+        _targetedInterfaces.push(newTargetedInterface_);
+    }
+
     // Functions for forge:
     // These are called by forge to run invariant tests and don't need to be called in tests.
 
@@ -89,4 +100,8 @@ abstract contract StdInvariant {
     function targetSenders() public view returns (address[] memory targetedSenders_) {
         targetedSenders_ = _targetedSenders;
     }
+
+    function targetInterfaces() public view returns (FuzzInterface[] memory targetedInterfaces_) {
+        targetedInterfaces_ = _targetedInterfaces;
+    }
 }