Completed test coverage for createsuperuser command.

django/contrib/auth/management/commands/createsuperuser.py

@@ -282,13 +282,11 @@ class Command(BaseCommand):
     def username_is_unique(self):
         if self.username_field.unique:
             return True
-        for unique_constraint in self.UserModel._meta.total_unique_constraints:
-            if (
-                len(unique_constraint.fields) == 1
-                and unique_constraint.fields[0] == self.username_field.name
-            ):
-                return True
-        return False
+        return any(
+            len(unique_constraint.fields) == 1
+            and unique_constraint.fields[0] == self.username_field.name
+            for unique_constraint in self.UserModel._meta.total_unique_constraints
+        )
 
     def _validate_username(self, username, verbose_field_name, database):
         """Validate username. If invalid, return a string error message."""

tests/auth_tests/test_management.py

@@ -312,6 +312,19 @@ class CreatesuperuserManagementCommandTestCase(TestCase):
         # created password should be unusable
         self.assertFalse(u.has_usable_password())
 
+    def test_validate_username(self):
+        msg = (
+            "Enter a valid username. This value may contain only letters, numbers, "
+            "and @/./+/-/_ characters."
+        )
+        with self.assertRaisesMessage(CommandError, msg):
+            call_command(
+                "createsuperuser",
+                interactive=False,
+                username="🤠",
+                email="joe@somewhere.org",
+            )
+
     def test_non_ascii_verbose_name(self):
         @mock_inputs(
             {