Suggest checking "pip config debug" in case of InvalidProxyURL error (#12690)

Author: nucccc

news/12649.feature.rst

@@ -0,0 +1 @@
+Suggest checking "pip config debug" in case of an InvalidProxyURL error.

src/pip/_internal/commands/install.py

@@ -8,6 +8,7 @@
 from typing import List, Optional
 
 from pip._vendor.packaging.utils import canonicalize_name
+from pip._vendor.requests.exceptions import InvalidProxyURL
 from pip._vendor.rich import print_json
 
 # Eagerly import self_outdated_check to avoid crashes. Otherwise,
@@ -766,6 +767,13 @@ def create_os_error_message(
             parts.append(permissions_part)
         parts.append(".\n")
 
+    # Suggest to check "pip config debug" in case of invalid proxy
+    if type(error) is InvalidProxyURL:
+        parts.append(
+            'Consider checking your local proxy configuration with "pip config debug"'
+        )
+        parts.append(".\n")
+
     # Suggest the user to enable Long Paths if path length is
     # more than 260
     if (

tests/unit/test_command_install.py

@@ -3,6 +3,8 @@
 
 import pytest
 
+from pip._vendor.requests.exceptions import InvalidProxyURL
+
 from pip._internal.commands import install
 from pip._internal.commands.install import create_os_error_message, decide_user_install
 
@@ -108,6 +110,16 @@ def test_most_cases(
             " file permission\nConsider using the `--user` option or check the"
             " permissions.\n",
         ),
+        # Testing custom InvalidProxyURL with help message
+        #  show_traceback = True, using_user_site = True
+        (
+            InvalidProxyURL(),
+            True,
+            True,
+            "Could not install packages due to an OSError.\n"
+            "Consider checking your local proxy configuration"
+            ' with "pip config debug".\n',
+        ),
     ],
 )
 def test_create_os_error_message(