config: rename MyOptionParser -> PytestArgumentParser

Initially wanted to rename it to `MyArgumentParser` to make it clearer
it's an `argparse.ArgumentParser`. But "My" looks funny, so change to
`Pytest` similar to `PytestPluginManager`.

Author: bluetech

src/_pytest/config/argparsing.py

@@ -115,10 +115,10 @@ def parse(
         strargs = [os.fspath(x) for x in args]
         return self.optparser.parse_args(strargs, namespace=namespace)
 
-    def _getparser(self) -> MyOptionParser:
+    def _getparser(self) -> PytestArgumentParser:
         from _pytest._argcomplete import filescompleter
 
-        optparser = MyOptionParser(self, self.extra_info, prog=self.prog)
+        optparser = PytestArgumentParser(self, self.extra_info, prog=self.prog)
         groups = [*self._groups, self._anonymous]
         for group in groups:
             if group.options:
@@ -437,7 +437,7 @@ def _addoption_instance(self, option: Argument, shortupper: bool = False) -> Non
         self.options.append(option)
 
 
-class MyOptionParser(argparse.ArgumentParser):
+class PytestArgumentParser(argparse.ArgumentParser):
     def __init__(
         self,
         parser: Parser,

src/_pytest/helpconfig.py

@@ -13,8 +13,8 @@
 from _pytest.config import Config
 from _pytest.config import ExitCode
 from _pytest.config import PrintHelp
-from _pytest.config.argparsing import MyOptionParser
 from _pytest.config.argparsing import Parser
+from _pytest.config.argparsing import PytestArgumentParser
 from _pytest.terminal import TerminalReporter
 import pytest
 
@@ -51,7 +51,7 @@ def __call__(
         setattr(namespace, self.dest, self.const)
 
         # We should only skip the rest of the parsing after preparse is done.
-        assert isinstance(parser, MyOptionParser)
+        assert isinstance(parser, PytestArgumentParser)
         if getattr(parser._parser, "after_preparse", False):
             raise PrintHelp