text: from clipmanager.singleinstance import SingleInstance
  
  
  def test_single_instance():
      app = SingleInstance()
      assert not app.is_running()
      app.destroy()
  
  
  def test_duplicate_instance():
      app_a, app_b = SingleInstance(), SingleInstance()
      assert not app_a.is_running()
      assert app_b.is_running()
      app_a.destroy()
      app_b.destroy()
  