Fixed #28398 -- Added suggestions for mistyped management commands.

django/core/management/__init__.py

@@ -3,6 +3,7 @@ import os
 import pkgutil
 import sys
 from collections import OrderedDict, defaultdict
+from difflib import get_close_matches
 from importlib import import_module
 
 import django
@@ -203,10 +204,11 @@ class ManagementUtility:
                 settings.INSTALLED_APPS
             else:
                 sys.stderr.write("No Django settings specified.\n")
-            sys.stderr.write(
-                "Unknown command: %r\nType '%s help' for usage.\n"
-                % (subcommand, self.prog_name)
-            )
+            possible_matches = get_close_matches(subcommand, commands)
+            sys.stderr.write('Unknown command: %r' % subcommand)
+            if possible_matches:
+                sys.stderr.write('. Did you mean %s?' % possible_matches[0])
+            sys.stderr.write("\nType '%s help' for usage.\n" % self.prog_name)
             sys.exit(1)
         if isinstance(app_name, BaseCommand):
             # If the command is already loaded, use it directly.

tests/admin_scripts/tests.py

@@ -2256,3 +2256,23 @@ class MainModule(AdminScriptTestCase):
     def test_program_name_in_help(self):
         out, err = self.run_test('-m', ['django', 'help'])
         self.assertOutput(out, "Type 'python -m django help <subcommand>' for help on a specific subcommand.")
+
+
+class DjangoAdminSuggestions(AdminScriptTestCase):
+    def setUp(self):
+        self.write_settings('settings.py')
+
+    def tearDown(self):
+        self.remove_settings('settings.py')
+
+    def test_suggestions(self):
+        args = ['rnserver', '--settings=test_project.settings']
+        out, err = self.run_django_admin(args)
+        self.assertNoOutput(out)
+        self.assertOutput(err, "Unknown command: 'rnserver'. Did you mean runserver?")
+
+    def test_no_suggestions(self):
+        args = ['abcdef', '--settings=test_project.settings']
+        out, err = self.run_django_admin(args)
+        self.assertNoOutput(out)
+        self.assertNotInOutput(err, 'Did you mean')