log output if tests fail before mutating

slither/tools/mutator/__main__.py

@@ -163,7 +163,7 @@ def main() -> (None):  # pylint: disable=too-many-statements,too-many-branches,t
     contract_names: Optional[List[str]] = args.contract_names
     comprehensive_flag: Optional[bool] = args.comprehensive
 
-    logger.info(blue(f"Starting Mutation Campaign in '{args.codebase}"))
+    logger.info(blue(f"Starting mutation campaign in {args.codebase}"))
 
     if paths_to_ignore:
         paths_to_ignore_list = paths_to_ignore.strip("][").split(",")
@@ -200,8 +200,9 @@ def main() -> (None):  # pylint: disable=too-many-statements,too-many-branches,t
 
     # run and time tests, abort if they're broken
     start_time = time.time()
-    if not run_test_cmd(test_command, None, None):  # no timeout or target_file during the first run
-        logger.error(red("Test suite fails before mutation, aborting"))
+    # no timeout or target_file during the first run, but be verbose on failure
+    if not run_test_cmd(test_command, None, None, True):
+        logger.error(red("Test suite fails with mutations, aborting"))
         return
     elapsed_time = round(time.time() - start_time)
 

slither/tools/mutator/utils/testing_generated_mutant.py

@@ -21,7 +21,7 @@ def compile_generated_mutant(file_path: str, mappings: str) -> bool:
         return False
 
 
-def run_test_cmd(cmd: str, timeout: int | None, target_file: str | None) -> bool:
+def run_test_cmd(cmd: str, timeout: int | None, target_file: str | None, verbose: bool) -> bool:
     """
     function to run codebase tests
     returns: boolean whether the tests passed or not
@@ -64,7 +64,13 @@ def run_test_cmd(cmd: str, timeout: int | None, target_file: str | None) -> bool
     # if result is 0 then it is an uncaught mutant because tests didn't fail
     if result:
         code = result.returncode
-        return code == 0
+        if code == 0:
+            return True
+
+    # If tests fail in verbose-mode, print both stdout and stderr for easier debugging
+    if verbose:
+        logger.info(yellow(result.stdout.decode('utf-8')))
+        logger.info(red(result.stderr.decode('utf-8')))
 
     return False
 
@@ -92,7 +98,7 @@ def test_patch(  # pylint: disable=too-many-arguments
     with open(file, "w", encoding="utf-8") as filepath:
         filepath.write(replaced_content)
     if compile_generated_mutant(file, mappings):
-        if run_test_cmd(command, timeout, file):
+        if run_test_cmd(command, timeout, file, False):
             create_mutant_file(file, generator_name)
             logger.info(
                 red(