diff --git a/tests/auth_tests/test_auth_backends.py b/tests/auth_tests/test_auth_backends.py
index 0c516dda34..ea9ddd426c 100644
--- a/tests/auth_tests/test_auth_backends.py
+++ b/tests/auth_tests/test_auth_backends.py
@@ -583,20 +583,33 @@ class TypeErrorBackend:
         raise TypeError
 
 
-class TypeErrorBackendTest(TestCase):
-    """
-    A TypeError within a backend is propagated properly (#18171).
-    """
-    backend = 'auth_tests.test_auth_backends.TypeErrorBackend'
+class SkippedBackend:
+    def authenticate(self):
+        # Doesn't accept any credentials so is skipped by authenticate().
+        pass
 
+
+class AuthenticateTests(TestCase):
     def setUp(self):
         self.user1 = User.objects.create_user('test', 'test@example.com', 'test')
 
-    @override_settings(AUTHENTICATION_BACKENDS=[backend])
+    @override_settings(AUTHENTICATION_BACKENDS=['auth_tests.test_auth_backends.TypeErrorBackend'])
     def test_type_error_raised(self):
+        """A TypeError within a backend is propagated properly (#18171)."""
         with self.assertRaises(TypeError):
             authenticate(username='test', password='test')
 
+    @override_settings(AUTHENTICATION_BACKENDS=(
+        'auth_tests.test_auth_backends.SkippedBackend',
+        'django.contrib.auth.backends.ModelBackend',
+    ))
+    def test_skips_backends_without_arguments(self):
+        """
+        A backend (SkippedBackend) is ignored if it doesn't accept the
+        credentials as arguments.
+        """
+        self.assertEqual(authenticate(username='test', password='test'), self.user1)
+
 
 class ImproperlyConfiguredUserModelTest(TestCase):
     """
diff --git a/tests/auth_tests/test_management.py b/tests/auth_tests/test_management.py
index 28e8c6328e..20de17c163 100644
--- a/tests/auth_tests/test_management.py
+++ b/tests/auth_tests/test_management.py
@@ -1,4 +1,5 @@
 import builtins
+import getpass
 import sys
 from datetime import date
 from io import StringIO
@@ -110,6 +111,28 @@ class ChangepasswordManagementCommandTestCase(TestCase):
         self.stdout.close()
         self.stderr.close()
 
+    @mock.patch.object(getpass, 'getpass', return_value='password')
+    def test_get_pass(self, mock_get_pass):
+        call_command('changepassword', username='joe', stdout=self.stdout)
+        self.assertIs(User.objects.get(username='joe').check_password('password'), True)
+
+    @mock.patch.object(getpass, 'getpass', return_value='')
+    def test_get_pass_no_input(self, mock_get_pass):
+        with self.assertRaisesMessage(CommandError, 'aborted'):
+            call_command('changepassword', username='joe', stdout=self.stdout)
+
+    @mock.patch.object(changepassword.Command, '_get_pass', return_value='new_password')
+    def test_system_username(self, mock_get_pass):
+        """The system username is used if --username isn't provided."""
+        username = getpass.getuser()
+        User.objects.create_user(username=username, password='qwerty')
+        call_command('changepassword', stdout=self.stdout)
+        self.assertIs(User.objects.get(username=username).check_password('new_password'), True)
+
+    def test_nonexistent_username(self):
+        with self.assertRaisesMessage(CommandError, "user 'test' does not exist"):
+            call_command('changepassword', username='test', stdout=self.stdout)
+
     @mock.patch.object(changepassword.Command, '_get_pass', return_value='not qwerty')
     def test_that_changepassword_command_changes_joes_password(self, mock_get_pass):
         "Executing the changepassword management command should change joe's password"
@@ -183,6 +206,11 @@ class MultiDBChangepasswordManagementCommandTestCase(TestCase):
 )
 class CreatesuperuserManagementCommandTestCase(TestCase):
 
+    def test_no_email_argument(self):
+        new_io = StringIO()
+        with self.assertRaisesMessage(CommandError, 'You must use --email with --noinput.'):
+            call_command('createsuperuser', interactive=False, username='joe', stdout=new_io)
+
     def test_basic_usage(self):
         "Check the operation of the createsuperuser management command"
         # We can use the management command to create a superuser
diff --git a/tests/auth_tests/test_models.py b/tests/auth_tests/test_models.py
index f688c5ae74..142fbcc39c 100644
--- a/tests/auth_tests/test_models.py
+++ b/tests/auth_tests/test_models.py
@@ -147,6 +147,13 @@ class UserManagerTestCase(TestCase):
                 password='test', is_staff=False,
             )
 
+    def test_make_random_password(self):
+        allowed_chars = 'abcdefg'
+        password = UserManager().make_random_password(5, allowed_chars)
+        self.assertEqual(len(password), 5)
+        for char in password:
+            self.assertIn(char, allowed_chars)
+
 
 class AbstractBaseUserTests(TestCase):