Fixed #35920 -- Observed requires_system_checks in migrate and runserver.

Before, the full suite of system checks was run by these commands
regardless if requires_system_checks had been overridden.

Co-authored-by: Simon Charette <charette.s@gmail.com>

django/core/management/base.py

@@ -450,10 +450,8 @@ class BaseCommand:
             self.stderr = OutputWrapper(options["stderr"])
 
         if self.requires_system_checks and not options["skip_checks"]:
-            if self.requires_system_checks == ALL_CHECKS:
+            check_kwargs = self.get_check_kwargs(options)
-                self.check()
+            self.check(**check_kwargs)
-            else:
-                self.check(tags=self.requires_system_checks)
         if self.requires_migrations_checks:
             self.check_migrations()
         output = self.handle(*args, **options)
@@ -468,6 +466,11 @@ class BaseCommand:
             self.stdout.write(output)
         return output
 
+    def get_check_kwargs(self, options):
+        if self.requires_system_checks == ALL_CHECKS:
+            return {}
+        return {"tags": self.requires_system_checks}
+
     def check(
         self,
         app_configs=None,

django/core/management/commands/migrate.py

@@ -19,14 +19,8 @@ class Command(BaseCommand):
     help = (
         "Updates database schema. Manages both apps with migrations and those without."
     )
-    requires_system_checks = []
 
     def add_arguments(self, parser):
-        parser.add_argument(
-            "--skip-checks",
-            action="store_true",
-            help="Skip system checks.",
-        )
         parser.add_argument(
             "app_label",
             nargs="?",
@@ -95,12 +89,13 @@ class Command(BaseCommand):
             help="Delete nonexistent migrations from the django_migrations table.",
         )
 
+    def get_check_kwargs(self, options):
+        kwargs = super().get_check_kwargs(options)
+        return {**kwargs, "databases": [options["database"]]}
+
     @no_translations
     def handle(self, *args, **options):
         database = options["database"]
-        if not options["skip_checks"]:
-            self.check(databases=[database])
-
         self.verbosity = options["verbosity"]
         self.interactive = options["interactive"]
 

django/core/management/commands/runserver.py

@@ -27,8 +27,6 @@ naiveip_re = _lazy_re_compile(
 class Command(BaseCommand):
     help = "Starts a lightweight web server for development."
 
-    # Validation is called explicitly each time the server is reloaded.
-    requires_system_checks = []
     stealth_options = ("shutdown_message",)
     suppressed_base_arguments = {"--verbosity", "--traceback"}
 
@@ -61,11 +59,6 @@ class Command(BaseCommand):
             dest="use_reloader",
             help="Tells Django to NOT use the auto-reloader.",
         )
-        parser.add_argument(
-            "--skip-checks",
-            action="store_true",
-            help="Skip system checks.",
-        )
 
     def execute(self, *args, **options):
         if options["no_color"]:
@@ -79,6 +72,10 @@ class Command(BaseCommand):
         """Return the default WSGI handler for the runner."""
         return get_internal_wsgi_application()
 
+    def get_check_kwargs(self, options):
+        """Validation is called explicitly each time the server reloads."""
+        return {"tags": set()}
+
     def handle(self, *args, **options):
         if not settings.DEBUG and not settings.ALLOWED_HOSTS:
             raise CommandError("You must set settings.ALLOWED_HOSTS if DEBUG is False.")
@@ -132,7 +129,9 @@ class Command(BaseCommand):
 
         if not options["skip_checks"]:
             self.stdout.write("Performing system checks...\n\n")
-            self.check(display_num_errors=True)
+            check_kwargs = super().get_check_kwargs(options)
+            check_kwargs["display_num_errors"] = True
+            self.check(**check_kwargs)
         # Need to check migrations here, so can't use the
         # requires_migrations_check attribute.
         self.check_migrations()

docs/howto/custom-management-commands.txt

@@ -319,6 +319,21 @@ the :meth:`~BaseCommand.handle` method must be implemented.
     checks, and list of database aliases in the ``databases`` to run database
     related checks against them.
 
+.. method:: BaseCommand.get_check_kwargs(options)
+
+    .. versionadded:: 5.2
+
+    Supplies kwargs for the call to :meth:`check`, including transforming the
+    value of :attr:`requires_system_checks` to the ``tag`` kwarg.
+
+    Override this method to change the values supplied to :meth:`check`. For
+    example, to opt into database related checks you can override
+    ``get_check_kwargs()`` as follows::
+
+        def get_check_kwargs(self, options):
+            kwargs = super().get_check_kwargs(options)
+            return {**kwargs, "databases": [options["database"]]}
+
 .. _ref-basecommand-subclasses:
 
 ``BaseCommand`` subclasses

docs/releases/5.2.txt

@@ -279,6 +279,10 @@ Management Commands
   ``Command.autodetector`` attribute for subclasses to override in order to use
   a custom autodetector class.
 
+* The new :meth:`.BaseCommand.get_check_kwargs` method can be overridden in
+  custom commands to control the running of system checks, e.g. to opt into
+  database-dependent checks.
+
 Migrations
 ~~~~~~~~~~
 

tests/admin_scripts/tests.py

@@ -20,6 +20,8 @@ from user_commands.utils import AssertFormatterFailureCaughtContext
 
 from django import conf, get_version
 from django.conf import settings
+from django.core.checks import Error, Tags, register
+from django.core.checks.registry import registry
 from django.core.management import (
     BaseCommand,
     CommandError,
@@ -27,7 +29,7 @@ from django.core.management import (
     color,
     execute_from_command_line,
 )
-from django.core.management.base import LabelCommand
+from django.core.management.base import LabelCommand, SystemCheckError
 from django.core.management.commands.loaddata import Command as LoaddataCommand
 from django.core.management.commands.runserver import Command as RunserverCommand
 from django.core.management.commands.testserver import Command as TestserverCommand
@@ -1733,7 +1735,53 @@ class ManageRunserver(SimpleTestCase):
             stdout=self.output,
         )
         self.assertIn("Performing system checks...", self.output.getvalue())
-        mocked_check.assert_called()
+        mocked_check.assert_has_calls(
+            [mock.call(tags=set()), mock.call(display_num_errors=True)]
+        )
+
+    def test_custom_system_checks(self):
+        original_checks = registry.registered_checks.copy()
+
+        @register(Tags.signals)
+        def my_check(app_configs, **kwargs):
+            return [Error("my error")]
+
+        class CustomException(Exception):
+            pass
+
+        self.addCleanup(setattr, registry, "registered_checks", original_checks)
+
+        class CustomRunserverCommand(RunserverCommand):
+            """Rather than mock run(), raise immediately after system checks run."""
+
+            def check_migrations(self, *args, **kwargs):
+                raise CustomException
+
+        class CustomRunserverCommandWithSignalsChecks(CustomRunserverCommand):
+            requires_system_checks = [Tags.signals]
+
+        command = CustomRunserverCommandWithSignalsChecks()
+        with self.assertRaises(SystemCheckError):
+            call_command(
+                command,
+                use_reloader=False,
+                skip_checks=False,
+                stdout=StringIO(),
+                stderr=StringIO(),
+            )
+
+        class CustomMigrateCommandWithSecurityChecks(CustomRunserverCommand):
+            requires_system_checks = [Tags.security]
+
+        command = CustomMigrateCommandWithSecurityChecks()
+        with self.assertRaises(CustomException):
+            call_command(
+                command,
+                use_reloader=False,
+                skip_checks=False,
+                stdout=StringIO(),
+                stderr=StringIO(),
+            )
 
 
 class ManageRunserverMigrationWarning(TestCase):

tests/migrations/test_commands.py

@@ -8,6 +8,8 @@ from pathlib import Path
 from unittest import mock
 
 from django.apps import apps
+from django.core.checks import Error, Tags, register
+from django.core.checks.registry import registry
 from django.core.management import CommandError, call_command
 from django.core.management.base import SystemCheckError
 from django.core.management.commands.makemigrations import (
@@ -96,6 +98,7 @@ class MigrateTests(MigrationTestBase):
         self.assertTableNotExists("migrations_tribble")
         self.assertTableNotExists("migrations_book")
 
+    @mock.patch("django.core.management.base.BaseCommand.check")
     @override_settings(
         INSTALLED_APPS=[
             "django.contrib.auth",
@@ -103,10 +106,33 @@ class MigrateTests(MigrationTestBase):
             "migrations.migrations_test_apps.migrated_app",
         ]
     )
-    def test_migrate_with_system_checks(self):
+    def test_migrate_with_system_checks(self, mocked_check):
         out = io.StringIO()
         call_command("migrate", skip_checks=False, no_color=True, stdout=out)
         self.assertIn("Apply all migrations: migrated_app", out.getvalue())
+        mocked_check.assert_called_once()
+
+    def test_migrate_with_custom_system_checks(self):
+        original_checks = registry.registered_checks.copy()
+
+        @register(Tags.signals)
+        def my_check(app_configs, **kwargs):
+            return [Error("my error")]
+
+        self.addCleanup(setattr, registry, "registered_checks", original_checks)
+
+        class CustomMigrateCommandWithSignalsChecks(MigrateCommand):
+            requires_system_checks = [Tags.signals]
+
+        command = CustomMigrateCommandWithSignalsChecks()
+        with self.assertRaises(SystemCheckError):
+            call_command(command, skip_checks=False, stderr=io.StringIO())
+
+        class CustomMigrateCommandWithSecurityChecks(MigrateCommand):
+            requires_system_checks = [Tags.security]
+
+        command = CustomMigrateCommandWithSecurityChecks()
+        call_command(command, skip_checks=False, stdout=io.StringIO())
 
     @override_settings(
         INSTALLED_APPS=[