Add RNM mutator (Remove Negation)

slither/tools/mutator/mutators/RNM.py

@@ -0,0 +1,58 @@
+from slither.core.expressions.unary_operation import UnaryOperation, UnaryOperationType
+from slither.tools.mutator.mutators.abstract_mutator import AbstractMutator
+from slither.tools.mutator.utils.patch import create_patch_with_line
+from slither.visitors.expression.expression import ExpressionVisitor
+
+
+class RemoveNegationVisitor(ExpressionVisitor):
+    def __init__(self, expression, mutator, result):
+        self._mutator = mutator
+        self._result = result
+
+        # Traverse the expression AST
+        super().__init__(expression)
+
+    def _post_unary_operation(self, expression: UnaryOperation):
+        # Mutate only logical negation (!)
+        if expression.type != UnaryOperationType.BANG:
+            return
+
+        if not expression.source_mapping:
+            return
+
+        operand = expression.expression
+
+        # Replace '!expr' with 'expr'
+        create_patch_with_line(
+            self._result,
+            self._mutator.in_file,
+            expression.source_mapping.start,
+            expression.source_mapping.start + expression.source_mapping.length,
+            expression.source_mapping.content,
+            operand.source_mapping.content,
+            expression.source_mapping.lines[0],
+        )
+
+
+class RNM(AbstractMutator):
+    NAME = "RNM"
+    HELP = "Remove Negation"
+
+    def _mutate(self) -> dict:
+        result = {}
+
+        for function in self.contract.functions_and_modifiers_declared:
+            if not self.should_mutate_function(function):
+                continue
+
+            for node in function.nodes:
+                if not self.should_mutate_node(node):
+                    continue
+
+                expression = getattr(node, "expression", None)
+                if expression is None:
+                    continue
+
+                RemoveNegationVisitor(expression, self, result)
+
+        return result

slither/tools/mutator/mutators/all_mutators.py

@@ -13,3 +13,4 @@
 from slither.tools.mutator.mutators.ROR import ROR  # severity medium
 from slither.tools.mutator.mutators.RR import RR  # severity high
 from slither.tools.mutator.mutators.CR import CR  # severity high
+from slither.tools.mutator.mutators.RNM import RNM  # severity medium

tests/tools/mutator/test_data/test_source_unit/src/Counter.sol

@@ -21,4 +21,8 @@ contract Counter {
     function restrictedIncrement() public onlyOwner {
         number++;
     }
+
+    function checkNegation(uint256 newNumber) public pure {
+        assert(!(newNumber != 7));
+    }
 }

tests/tools/mutator/test_mutator.py

@@ -14,6 +14,7 @@
 from slither.tools.mutator.utils.file_handling import get_sol_file_list, backup_source_file
 from slither.utils.function import get_function_id
 from slither.tools.mutator.mutators.RR import RR
+from slither.tools.mutator.mutators.RNM import RNM
 
 
 TEST_DATA_DIR = Path(__file__).resolve().parent / "test_data"
@@ -283,3 +284,37 @@ def test_should_mutate_function_includes_modifier(solc_binary_path):
         for mod in contract.modifiers:
             if mod.name == "onlyOwner":
                 assert mutator.should_mutate_function(mod) is True
+
+
+def test_rnm_mutates_negation(solc_binary_path):
+    """Negations used by target function should be mutated"""
+    solc_path = solc_binary_path("0.8.15")
+    file_path = (TEST_DATA_DIR / "test_source_unit" / "src" / "Counter.sol").as_posix()
+    sl = Slither(file_path, solc=solc_path, compile_force_framework="solc")
+
+    contract = next(c for c in sl.contracts if c.name == "Counter")
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        mutator = RNM(
+            sl.compilation_units[0],
+            timeout=30,
+            testing_command="true",
+            testing_directory=None,
+            contract_instance=contract,
+            solc_remappings=None,
+            verbose=False,
+            output_folder=Path(tmpdir),
+            dont_mutate_line=[],
+            target_selectors=None,
+            target_modifiers=None,
+        )
+
+        patches = mutator._mutate()
+
+        assert "patches" in patches
+        assert file_path in patches["patches"]
+
+        assert any(
+            patch["old_string"] == "!(newNumber != 7)" and patch["new_string"] == "(newNumber != 7)"
+            for patch in patches["patches"][file_path]
+        )