git_auth: Handle conflicting stale local config (reland)

As we prefer configuring the global config, it's possible to leave
stale local config behind if the user is swapping between emails.

Originally:
https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/7213753

Fixed to skip clearing local config when not inside a repo (as that errors).

Bug: 466343784
Change-Id: I8b34d24ba3966c66aeebaf11bd0368dfb4b0da28
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/7265721
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Allen Li <ayatane@chromium.org>

tests/git_auth_test.py

@@ -15,6 +15,7 @@ import sys
 import tempfile
 from typing import Iterable
 import unittest
+from unittest import mock
 import urllib.parse
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
@@ -101,7 +102,7 @@ class TestConfigWizard(unittest.TestCase):
         }
         self.assertEqual(self.global_state, want)
 
-    def test_configure_review_sso_global(self):
+    def test_configure_sso_global_with_review_host(self):
         parts = urllib.parse.urlsplit(
             'https://chromium-review.googlesource.com/chromium/tools/depot_tools.git'
         )
@@ -124,7 +125,7 @@ class TestConfigWizard(unittest.TestCase):
         }
         self.assertEqual(self.global_state, want)
 
-    def test_configure_review_oauth_global(self):
+    def test_configure_oauth_global_with_review_host(self):
         parts = urllib.parse.urlsplit(
             'https://chromium-review.googlesource.com/chromium/tools/depot_tools.git'
         )
@@ -190,6 +191,68 @@ class TestConfigWizard(unittest.TestCase):
                 'https://chromium-review.googlesource.com/chromium/tools/depot_tools.git',
             ])
 
+    @mock.patch('git_auth.ConfigWizard._check_use_sso', spec=True)
+    def test_configure_host_clears_conflicting_local_stale(self, check):
+        parts = urllib.parse.urlsplit(
+            'https://chromium.googlesource.com/chromium/tools/depot_tools.git')
+        email = 'columbina@example.com'
+
+        check.return_value = True
+        self.wizard._configure_host(parts, email, scope='local')
+        # Check local rule is created
+        self.assertEqual(
+            scm.GIT.GetConfigList(os.getcwd(), 'url.sso://chromium/.insteadof'),
+            [
+                'https://chromium.googlesource.com/',
+                'https://chromium-review.googlesource.com/',
+            ])
+
+        check.return_value = False
+        self.wizard._configure_host(parts, email, scope='global')
+        want = {
+            'credential.https://chromium.googlesource.com.helper': ['', 'luci'],
+            'credential.https://chromium.googlesource.com.usehttppath': ['yes'],
+        }
+        self.assertEqual(self.global_state, want)
+        # Ensure the local rule gets purged
+        self.assertEqual(
+            scm.GIT.GetConfigList(os.getcwd(), 'url.sso://chromium/.insteadof'),
+            [])
+
+    @mock.patch('git_auth.ConfigWizard._check_use_sso', spec=True)
+    def test_configure_host_outside_repo_keeps_local_stale(self, check):
+        parts = urllib.parse.urlsplit(
+            'https://chromium.googlesource.com/chromium/tools/depot_tools.git')
+        email = 'columbina@example.com'
+
+        check.return_value = True
+        self.wizard._configure_host(parts, email, scope='local')
+        # Check local rule is created
+        self.assertEqual(
+            scm.GIT.GetConfigList(os.getcwd(), 'url.sso://chromium/.insteadof'),
+            [
+                'https://chromium.googlesource.com/',
+                'https://chromium-review.googlesource.com/',
+            ])
+
+        check.return_value = False
+        wizard = git_auth.ConfigWizard(ui=self.ui, remote_url_func=lambda: '')
+        wizard._configure_host(parts, email, scope='global')
+        want = {
+            'credential.https://chromium.googlesource.com.helper': ['', 'luci'],
+            'credential.https://chromium.googlesource.com.usehttppath': ['yes'],
+        }
+        self.assertEqual(self.global_state, want)
+        # Check the local rule remains.
+        # This test is wonky because the scm.GIT mock always assumes we're in a repo
+        self.assertEqual(
+            scm.GIT.GetConfigList(os.getcwd(), 'url.sso://chromium/.insteadof'),
+            [
+                'https://chromium.googlesource.com/',
+                'https://chromium-review.googlesource.com/',
+            ])
+
+
     def test_check_gitcookies_same(self):
         with tempfile.NamedTemporaryFile() as gitcookies:
             self.wizard._gitcookies = lambda: gitcookies.name