class_docstr: Registers fake backends with the Store to test options on.
class_docstr_tok: ["Registers","fake","backends","with","the","Store","to","test","options","on","."]
code: def setUp(self):
      super().setUp()
      self.current_backend = Store.current_backend
      self.register_custom(
          ExampleElement, "backend_1", ["plot_custom1"]
      )
      self.register_custom(
          ExampleElement, "backend_2", ["plot_custom2"]
      )
      Store.set_current_backend("backend_1")
  
imports: import gc
  from holoviews.core.element import Element
  from holoviews.core.options import Keywords, Options, OptionTree, Store
  from holoviews.core.spaces import HoloMap
  from ..utils import LoggingComparisonTestCase
label_desc: Use image node_id 1 for calling the CustomBackendTestCase obj's underlying member method code with example usage: obj.setUp() without return types