code: def test_get_username(
      app_context: AppContext,
      mocker: MockFixture,
      username: Optional[str],
  ) -> None:
      mock_g = mocker.patch("superset.utils.core.g", spec={})
      mock_g.user = security_manager.find_user(username)
      assert get_username() == username
  
imports: import unittest
  from typing import Optional
  import pytest
  from flask.ctx import AppContext
  from pytest_mock import MockFixture
  from sqlalchemy import inspect
  from tests.integration_tests.fixtures.birth_names_dashboard import load_birth_names_dashboard_with_slices, load_birth_names_data
  from tests.integration_tests.fixtures.world_bank_dashboard import load_world_bank_dashboard_with_slices, load_world_bank_data
  from tests.integration_tests.fixtures.energy_dashboard import load_energy_table_with_slice, load_energy_table_data
  from tests.integration_tests.test_app import app
  from superset import db, security_manager
  from superset.connectors.sqla.models import SqlaTable
  from superset.models import core
  from superset.utils.core import get_user_id, get_username, override_user
  from superset.utils.database import get_example_database
  from .base_tests import SupersetTestCase
label_desc: Use image node_id 2 for calling a global function with example usage: test_get_username(app_context, mocker, username) without return types