Add type annotations to _pytest.config.argparsing and corresponding Config code

src/_pytest/_argcomplete.py

@@ -53,19 +53,22 @@
   which should throw a KeyError: 'COMPLINE' (which is properly set by the
   global argcomplete script).
 """
+import argparse
 import os
 import sys
 from glob import glob
+from typing import Any
+from typing import List
 from typing import Optional
 
 
 class FastFilesCompleter:
     "Fast file completer class"
 
-    def __init__(self, directories=True):
+    def __init__(self, directories: bool = True) -> None:
         self.directories = directories
 
-    def __call__(self, prefix, **kwargs):
+    def __call__(self, prefix: str, **kwargs: Any) -> List[str]:
         """only called on non option completions"""
         if os.path.sep in prefix[1:]:
             prefix_dir = len(os.path.dirname(prefix) + os.path.sep)
@@ -94,13 +97,13 @@ def __call__(self, prefix, **kwargs):
         sys.exit(-1)
     filescompleter = FastFilesCompleter()  # type: Optional[FastFilesCompleter]
 
-    def try_argcomplete(parser):
+    def try_argcomplete(parser: argparse.ArgumentParser) -> None:
         argcomplete.autocomplete(parser, always_complete_options=False)
 
 
 else:
 
-    def try_argcomplete(parser):
+    def try_argcomplete(parser: argparse.ArgumentParser) -> None:
         pass
 
     filescompleter = None

src/_pytest/config/__init__.py

@@ -45,6 +45,8 @@
 if False:  # TYPE_CHECKING
     from typing import Type
 
+    from .argparsing import Argument
+
 
 hookimpl = HookimplMarker("pytest")
 hookspec = HookspecMarker("pytest")
@@ -679,7 +681,7 @@ class InvocationParams:
         plugins = attr.ib()
         dir = attr.ib(type=Path)
 
-    def __init__(self, pluginmanager, *, invocation_params=None):
+    def __init__(self, pluginmanager, *, invocation_params=None) -> None:
         from .argparsing import Parser, FILE_OR_DIR
 
         if invocation_params is None:
@@ -792,19 +794,19 @@ def fromdictargs(cls, option_dict, args):
             config.pluginmanager.consider_pluginarg(x)
         return config
 
-    def _processopt(self, opt):
+    def _processopt(self, opt: "Argument") -> None:
         for name in opt._short_opts + opt._long_opts:
             self._opt2dest[name] = opt.dest
 
-        if hasattr(opt, "default") and opt.dest:
+        if hasattr(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):
         self.pluginmanager._set_initial_conftests(early_config.known_args_namespace)
 
-    def _initini(self, args) -> None:
+    def _initini(self, args: Sequence[str]) -> None:
         ns, unknown_args = self._parser.parse_known_and_unknown_args(
             args, namespace=copy.copy(self.option)
         )
@@ -821,7 +823,7 @@ def _initini(self, args) -> None:
         self._parser.addini("minversion", "minimally required pytest version")
         self._override_ini = ns.override_ini or ()
 
-    def _consider_importhook(self, args):
+    def _consider_importhook(self, args: Sequence[str]) -> None:
         """Install the PEP 302 import hook if using assertion rewriting.
 
         Needs to parse the --assert=<mode> option from the commandline
@@ -861,19 +863,19 @@ def _mark_plugins_for_rewrite(self, hook):
         for name in _iter_rewritable_modules(package_files):
             hook.mark_rewrite(name)
 
-    def _validate_args(self, args, via):
+    def _validate_args(self, args: List[str], via: str) -> List[str]:
         """Validate known args."""
-        self._parser._config_source_hint = via
+        self._parser._config_source_hint = via  # type: ignore
         try:
             self._parser.parse_known_and_unknown_args(
                 args, namespace=copy.copy(self.option)
             )
         finally:
-            del self._parser._config_source_hint
+            del self._parser._config_source_hint  # type: ignore
 
         return args
 
-    def _preparse(self, args, addopts=True):
+    def _preparse(self, args: List[str], addopts: bool = True) -> None:
         if addopts:
             env_addopts = os.environ.get("PYTEST_ADDOPTS", "")
             if len(env_addopts):
@@ -937,7 +939,7 @@ def _checkversion(self):
                     )
                 )
 
-    def parse(self, args, addopts=True):
+    def parse(self, args: List[str], addopts: bool = True) -> None:
         # parse given cmdline arguments into this config object.
         assert not hasattr(
             self, "args"
@@ -948,7 +950,7 @@ def parse(self, args, addopts=True):
         self._preparse(args, addopts=addopts)
         # XXX deprecated hook:
         self.hook.pytest_cmdline_preparse(config=self, args=args)
-        self._parser.after_preparse = True
+        self._parser.after_preparse = True  # type: ignore
         try:
             args = self._parser.parse_setoption(
                 args, self.option, namespace=self.option