More cleanups mostly around config

src/_pytest/config/__init__.py

@@ -18,6 +18,7 @@
 import enum
 from functools import lru_cache
 import glob
+import importlib
 import importlib.metadata
 import inspect
 import os
@@ -55,6 +56,7 @@
 from _pytest._code.code import TracebackStyle
 from _pytest._io import TerminalWriter
 from _pytest.compat import assert_never
+from _pytest.compat import NOTSET
 from _pytest.config.argparsing import Argument
 from _pytest.config.argparsing import FILE_OR_DIR
 from _pytest.config.argparsing import Parser
@@ -873,7 +875,7 @@ def import_plugin(self, modname: str, consider_entry_points: bool = False) -> No
                 return
 
         try:
-            __import__(importspec)
+            mod = importlib.import_module(importspec)
         except ImportError as e:
             raise ImportError(
                 f'Error importing plugin "{modname}": {e.args[0]}'
@@ -882,7 +884,6 @@ def import_plugin(self, modname: str, consider_entry_points: bool = False) -> No
         except Skipped as e:
             self.skipped_plugins.append((modname, e.msg or ""))
         else:
-            mod = sys.modules[importspec]
             self.register(mod, modname)
 
 
@@ -907,14 +908,6 @@ def _get_plugin_specs_as_list(
     )
 
 
-class Notset:
-    def __repr__(self):
-        return "<NOTSET>"
-
-
-notset = Notset()
-
-
 def _iter_rewritable_modules(package_files: Iterable[str]) -> Iterator[str]:
     """Given an iterable of file names in a source distribution, return the "names" that should
     be marked for assertion rewrite.
@@ -1090,7 +1083,6 @@ def __init__(
         self.trace = self.pluginmanager.trace.root.get("config")
         self.hook: pluggy.HookRelay = PathAwareHookProxy(self.pluginmanager.hook)  # type: ignore[assignment]
         self._inicache: dict[str, Any] = {}
-        self._opt2dest: dict[str, str] = {}
         self._cleanup_stack = contextlib.ExitStack()
         self.pluginmanager.register(self, "pytestconfig")
         self._configured = False
@@ -1215,12 +1207,8 @@ def fromdictargs(cls, option_dict: Mapping[str, Any], args: list[str]) -> Config
         return config
 
     def _processopt(self, opt: Argument) -> None:
-        for name in opt._short_opts + opt._long_opts:
-            self._opt2dest[name] = opt.dest
-
-        if hasattr(opt, "default"):
-            if not hasattr(self.option, opt.dest):
-                setattr(self.option, opt.dest, opt.default)
+        if not hasattr(self.option, opt.dest):
+            setattr(self.option, opt.dest, opt.default)
 
     @hookimpl(trylast=True)
     def pytest_load_initial_conftests(self, early_config: Config) -> None:
@@ -1376,17 +1364,11 @@ def pytest_collection(self) -> Generator[None, object, object]:
     def _checkversion(self) -> None:
         import pytest
 
-        minver_ini_value = self.inicfg.get("minversion", None)
-        minver = minver_ini_value.value if minver_ini_value is not None else None
+        minver = self.getini("minversion")
         if minver:
             # Imported lazily to improve start-up time.
             from packaging.version import Version
 
-            if not isinstance(minver, str):
-                raise pytest.UsageError(
-                    f"{self.inipath}: 'minversion' must be a single value"
-                )
-
             if Version(minver) > Version(pytest.__version__):
                 raise pytest.UsageError(
                     f"{self.inipath}: 'minversion' requires pytest-{minver}, actual pytest-{pytest.__version__}'"
@@ -1840,7 +1822,7 @@ def _getconftest_pathlist(
             values.append(relroot)
         return values
 
-    def getoption(self, name: str, default: Any = notset, skip: bool = False):
+    def getoption(self, name: str, default: Any = NOTSET, skip: bool = False):
         """Return command line option value.
 
         :param name: Name of the option. You may also specify
@@ -1850,14 +1832,14 @@ def getoption(self, name: str, default: Any = notset, skip: bool = False):
         :param skip: If ``True``, raise :func:`pytest.skip` if option is undeclared or has a ``None`` value.
             Note that even if ``True``, if a default was specified it will be returned instead of a skip.
         """
-        name = self._opt2dest.get(name, name)
+        name = self._parser._opt2dest.get(name, name)
         try:
             val = getattr(self.option, name)
             if val is None and skip:
                 raise AttributeError(name)
             return val
         except AttributeError as e:
-            if default is not notset:
+            if default is not NOTSET:
                 return default
             if skip:
                 import pytest
@@ -2134,7 +2116,7 @@ def _resolve_warning_category(category: str) -> type[Warning]:
         klass = category
     else:
         module, _, klass = category.rpartition(".")
-        m = __import__(module, None, None, [klass])
+        m = importlib.import_module(module)
     cat = getattr(m, klass)
     if not issubclass(cat, Warning):
         raise UsageError(f"{cat} is not a Warning subclass")