Suggest possibly misspelled arguments, e.g.

> locust -extra-files
locust: error: unrecognized arguments: -extra-files
Did you mean '--extra-files'?

Author: cyberw

locust/argument_parser.py

@@ -7,6 +7,7 @@
 import argparse
 import ast
 import atexit
+import difflib
 import json
 import os
 import platform
@@ -60,6 +61,18 @@ class LocustArgumentParser(configargparse.ArgumentParser):
     optionally exclude arguments from the UI.
     """
 
+    def error(self, message):
+        # Extract the unknown option from the error message
+        if "unrecognized arguments:" in message:
+            bad_arg = message.split("unrecognized arguments:")[1].strip().split()[0]
+            # Compare with known arguments
+            options = [action.option_strings for action in self._actions]
+            options = [opt for sublist in options for opt in sublist]  # flatten
+            suggestion = difflib.get_close_matches(bad_arg, options, n=1)
+            if suggestion:
+                message += f"\nDid you mean '{suggestion[0]}'?"
+        self.exit(2, f"{self.prog}: error: {message}\n")
+
     def add_argument(self, *args, **kwargs) -> configargparse.Action:
         """
         This method supports the same args as ArgumentParser.add_argument(..)

locust/test/test_parser.py

@@ -294,8 +294,9 @@ def test_parse_locustfile_invalid_directory_error(self):
                 )
 
     def test_unknown_command_line_arg(self):
+        err = StringIO()
         with self.assertRaises(SystemExit):
-            with mock.patch("sys.stderr", new=StringIO()):
+            with mock.patch("sys.stderr", new=err):
                 parse_options(
                     args=[
                         "-f",
@@ -309,10 +310,13 @@ def test_unknown_command_line_arg(self):
                         "--reset-stats",
                         "--stop-timeout",
                         "5",
-                        "--unknown-flag",
+                        "--unknown-flag-extra-files",
                         "MyUserClass",
                     ]
                 )
+        err.seek(0)
+        stderr = err.read()
+        self.assertIn("Did you mean '--extra-files'", stderr)
 
     def test_custom_argument(self):
         @locust.events.init_command_line_parser.add_listener