Method register

src/_pytest/config/__init__.py:447–468

(
        self, plugin: _PluggyPlugin, name: Optional[str] = None
    )

        return opts

    def register(
        self, plugin: _PluggyPlugin, name: Optional[str] = None
    ) -> Optional[str]:
        if name in _pytest.deprecated.DEPRECATED_EXTERNAL_PLUGINS:
            warnings.warn(
                PytestConfigWarning(
                    "{} plugin has been merged into the core, "
                    "please remove it from your requirements.".format(
                        name.replace("_", "-")
                    )
                )
            )
            return None
        ret: Optional[str] = super().register(plugin, name)
        if ret:
            self.hook.pytest_plugin_registered.call_historic(
                kwargs=dict(plugin=plugin, manager=self)
            )

            if isinstance(plugin, types.ModuleType):
                self.consider_module(plugin)
        return ret

    def getplugin(self, name: str):
        # Support deprecated naming because plugins (xdist e.g.) use it.