PYTHON-3036 Improve error message for unknown MongoClient options (#1440)

doc/contributors.rst

@@ -98,3 +98,4 @@ The following is a list of people who have contributed to
 - Dainis Gorbunovs (DainisGorbunovs)
 - Iris Ho (sleepyStick)
 - Stephan Hof (stephan-hof)
+- Casey Clements (caseyclements)

pymongo/common.py

@@ -20,6 +20,7 @@ import datetime
 import inspect
 import warnings
 from collections import OrderedDict, abc
+from difflib import get_close_matches
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -162,9 +163,12 @@ def clean_node(node: str) -> tuple[str, int]:
     return host.lower(), port
 
 
-def raise_config_error(key: str, dummy: Any) -> NoReturn:
+def raise_config_error(key: str, suggestions: Optional[list] = None) -> NoReturn:
     """Raise ConfigurationError with the given key name."""
-    raise ConfigurationError(f"Unknown option {key}")
+    msg = f"Unknown option: {key}."
+    if suggestions:
+        msg += f" Did you mean one of ({', '.join(suggestions)}) or maybe a camelCase version of one? Refer to docstring."
+    raise ConfigurationError(msg)
 
 
 # Mapping of URI uuid representation options to valid subtypes.
@@ -810,14 +814,24 @@ def validate_auth_option(option: str, value: Any) -> tuple[str, Any]:
     """Validate optional authentication parameters."""
     lower, value = validate(option, value)
     if lower not in _AUTH_OPTIONS:
-        raise ConfigurationError(f"Unknown authentication option: {option}")
+        raise ConfigurationError(f"Unknown option: {option}. Must be in {_AUTH_OPTIONS}")
     return option, value
 
 
+def _get_validator(
+    key: str, validators: dict[str, Callable[[Any, Any], Any]], normed_key: Optional[str] = None
+) -> Callable:
+    normed_key = normed_key or key
+    try:
+        return validators[normed_key]
+    except KeyError:
+        suggestions = get_close_matches(normed_key, validators, cutoff=0.2)
+        raise_config_error(key, suggestions)
+
+
 def validate(option: str, value: Any) -> tuple[str, Any]:
     """Generic validation function."""
-    lower = option.lower()
-    validator = VALIDATORS.get(lower, raise_config_error)
+    validator = _get_validator(option, VALIDATORS, normed_key=option.lower())
     value = validator(option, value)
     return option, value
 
@@ -855,15 +869,15 @@ def get_validated_options(
     for opt, value in options.items():
         normed_key = get_normed_key(opt)
         try:
-            validator = URI_OPTIONS_VALIDATOR_MAP.get(normed_key, raise_config_error)
-            value = validator(opt, value)  # noqa: PLW2901
+            validator = _get_validator(opt, URI_OPTIONS_VALIDATOR_MAP, normed_key=normed_key)
+            validated = validator(opt, value)
         except (ValueError, TypeError, ConfigurationError) as exc:
             if warn:
                 warnings.warn(str(exc), stacklevel=2)
             else:
                 raise
         else:
-            validated_options[get_setter_key(normed_key)] = value
+            validated_options[get_setter_key(normed_key)] = validated
     return validated_options
 
 

test/test_client.py

@@ -21,6 +21,7 @@ import copy
 import datetime
 import gc
 import os
+import re
 import signal
 import socket
 import struct
@@ -535,6 +536,14 @@ class ClientUnitTest(unittest.TestCase):
         self.assertIsInstance(c.options.retry_writes, bool)
         self.assertIsInstance(c.options.retry_reads, bool)
 
+    def test_validate_suggestion(self):
+        """Validate kwargs in constructor."""
+        for typo in ["auth", "Auth", "AUTH"]:
+            expected = f"Unknown option: {typo}. Did you mean one of (authsource, authmechanism, authoidcallowedhosts) or maybe a camelCase version of one? Refer to docstring."
+            expected = re.escape(expected)
+            with self.assertRaisesRegex(ConfigurationError, expected):
+                MongoClient(**{typo: "standard"})  # type: ignore[arg-type]
+
 
 class TestClient(IntegrationTest):
     def test_multiple_uris(self):

test/test_uri_parser.py

@@ -144,6 +144,12 @@ class TestURI(unittest.TestCase):
         self.assertEqual({"authsource": "foobar"}, split_options("authSource=foobar"))
         self.assertEqual({"maxpoolsize": 50}, split_options("maxpoolsize=50"))
 
+        # Test suggestions given when invalid kwarg passed
+
+        expected = r"Unknown option: auth. Did you mean one of \(authsource, authmechanism, timeoutms\) or maybe a camelCase version of one\? Refer to docstring."
+        with self.assertRaisesRegex(ConfigurationError, expected):
+            split_options("auth=GSSAPI")
+
     def test_parse_uri(self):
         self.assertRaises(InvalidURI, parse_uri, "http://foobar.com")
         self.assertRaises(InvalidURI, parse_uri, "http://foo@foobar.com")