code: def test_register_unknown_hooks(pm):
      class Plugin1(object):
          @hookimpl
          def he_method1(self, arg):
              return arg + 1
  
      pname = pm.register(Plugin1())
  
      class Hooks(object):
          @hookspec
          def he_method1(self, arg):
              pass
  
      pm.add_hookspecs(Hooks)
      # assert not pm._unverified_hooks
      assert pm.hook.he_method1(arg=1) == [2]
      assert len(pm.get_hookcallers(pm.get_plugin(pname))) == 1
  
imports: import pytest
  import types
  from pluggy import PluginManager, PluginValidationError, HookCallError, HookimplMarker, HookspecMarker
  from pluggy.manager import importlib_metadata
label_desc: Use image node_id 10 for calling a global function with example usage: test_register_unknown_hooks(pm) and returns: unknown