Ensure --outfile isn't a directory (#800)

Co-authored-by: sarahec <sarahec@nextquestion.net>

scalene/scalene_parseargs.py

@@ -37,6 +37,8 @@ def clean_exit(code: object = 0) -> NoReturn:
         """Replacement for sys.exit that exits cleanly from within Jupyter notebooks."""
         raise StopJupyterExecution
 
+
+
     @staticmethod
     def parse_args() -> Tuple[argparse.Namespace, List[str]]:
         # In IPython, intercept exit cleanly (because sys.exit triggers a backtrace).
@@ -353,6 +355,10 @@ def parse_args() -> Tuple[argparse.Namespace, List[str]]:
         # https://stackoverflow.com/questions/35733262/is-there-any-way-to-instruct-argparse-python-2-7-to-remove-found-arguments-fro
         args, left = parser.parse_known_args()
 
+        # Validate file/directory arguments
+        if args.outfile and os.path.isdir(args.outfile):
+            parser.error(f"outfile {args.outfile} is a directory")
+
         # Hack to simplify functionality for Windows platforms.
         if sys.platform == "win32":
             args.on = True

test/issues/test-issue691.py

@@ -0,0 +1,10 @@
+import sys
+import subprocess
+import tempfile
+
+dir = tempfile.TemporaryDirectory()
+cmd = [sys.executable, "-m", "scalene", "--cli", "--outfile", dir.name, "../testme.py", "--cpu-only"]
+
+print(cmd)
+print(f'If bug 691 is fixed, you will see \n    scalene: error: outfile {dir.name} is a directory')
+proc = subprocess.run(cmd)