Add CA cert info to debug, and corresponding tests

Added CA cert information to debug.py
Made the corresponding changes to tests/functional/test_debug.py

src/pip/_internal/commands/debug.py

@@ -5,8 +5,11 @@ from __future__ import absolute_import
 
 import locale
 import logging
+import os
 import sys
 
+from pip._vendor.certifi import where
+
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.cmdoptions import make_target_python
@@ -17,14 +20,14 @@ from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.wheel import format_tag
 
 if MYPY_CHECK_RUNNING:
-    from typing import Any, List
+    from typing import Any, List, Optional
     from optparse import Values
 
 logger = logging.getLogger(__name__)
 
 
 def show_value(name, value):
-    # type: (str, str) -> None
+    # type: (str, Optional[str]) -> None
     logger.info('{}: {}'.format(name, value))
 
 
@@ -75,6 +78,25 @@ def show_tags(options):
             logger.info(msg)
 
 
+def ca_bundle_info(config):
+    levels = set()
+    for key, value in config.items():
+        levels.add(key.split('.')[0])
+
+    if not levels:
+        return "Not specified"
+
+    levels_that_override_global = ['install', 'wheel', 'download']
+    global_overriding_level = [
+        level for level in levels if level in levels_that_override_global
+    ]
+    if not global_overriding_level:
+        return 'global'
+
+    levels.remove('global')
+    return ", ".join(levels)
+
+
 class DebugCommand(Command):
     """
     Display debug information.
@@ -90,6 +112,7 @@ class DebugCommand(Command):
         cmd_opts = self.cmd_opts
         cmdoptions.add_target_python_options(cmd_opts)
         self.parser.insert_option_group(0, cmd_opts)
+        self.parser.config.load()
 
     def run(self, options, args):
         # type: (Values, List[Any]) -> int
@@ -110,6 +133,11 @@ class DebugCommand(Command):
         show_value('sys.platform', sys.platform)
         show_sys_implementation()
 
+        show_value("REQUESTS_CA_BUNDLE", os.environ.get('REQUESTS_CA_BUNDLE'))
+        show_value("CURL_CA_BUNDLE", os.environ.get('CURL_CA_BUNDLE'))
+        show_value("pip._vendor.certifi.where()", where())
+        show_value("'cert' config value", ca_bundle_info(self.parser.config))
+
         show_tags(options)
 
         return SUCCESS

tests/functional/test_debug.py

@@ -10,6 +10,10 @@ from pip._internal import pep425tags
     'locale.getpreferredencoding: ',
     'sys.platform: ',
     'sys.implementation:',
+    'REQUESTS_CA_BUNDLE: ',
+    'CURL_CA_BUNDLE: ',
+    'pip._vendor.certifi.where(): ',
+    '\'cert\' config value: ',
 ])
 def test_debug(script, expected_text):
     """