move from optparse to argparse

30 files changed, 464 insertions, 304 deletions

diff --git a/.coveragerc b/.coveragerc
index 0a3db04..df0a929 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -1,11 +1,31 @@
 [run]
+parallel = True
 branch = True
 source =
     flake8
-
+omit =
+    # Don't complain if non-runnable code isn't run
+    */__main__.py
 
 [paths]
 source =
     src/flake8
     .tox/*/lib/python*/site-packages/flake8
     .tox/pypy/site-packages/flake8
+
+[report]
+show_missing = True
+skip_covered = True
+exclude_lines =
+    # Have to re-enable the standard pragma
+    \#\s*pragma: no cover
+
+    # Don't complain if tests don't hit defensive assertion code:
+    ^\s*raise AssertionError\b
+    ^\s*raise NotImplementedError\b
+    ^\s*return NotImplemented\b
+    ^\s*raise$
+
+    # Don't complain if non-runnable code isn't run:
+    ^if __name__ == ['"]__main__['"]:$
+    ^\s*if False:
diff --git a/.pylintrc b/.pylintrc
index d6e52a8..a23de97 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -354,10 +354,6 @@ max-bool-expr=5
 
 
 [IMPORTS]
-
-# Deprecated modules which should not be used, separated by a comma
-deprecated-modules=optparse
-
 # Create a graph of every (i.e. internal and external) dependencies in the
 # given file (report RP0402 must not be disabled)
 import-graph=
diff --git a/docs/source/internal/option_handling.rst b/docs/source/internal/option_handling.rst
index 86b7021..dd76706 100644
--- a/docs/source/internal/option_handling.rst
+++ b/docs/source/internal/option_handling.rst
@@ -28,7 +28,7 @@ undocumented attribute that pep8 looks for, |Flake8| 3 now accepts a parameter
 to ``add_option``, specifically ``parse_from_config`` which is a boolean
 value.
 
-|Flake8| does this by creating its own abstractions on top of :mod:`optparse`.
+|Flake8| does this by creating its own abstractions on top of :mod:`argparse`.
 The first abstraction is the :class:`flake8.options.manager.Option` class. The
 second is the :class:`flake8.options.manager.OptionManager`. In fact, we add
 three new parameters:
@@ -219,7 +219,7 @@ API Documentation
 .. autofunction:: flake8.options.aggregator.aggregate_options
 
 .. autoclass:: flake8.options.manager.Option
-    :members: __init__, normalize, to_optparse
+    :members: __init__, normalize, to_argparse
 
 .. autoclass:: flake8.options.manager.OptionManager
     :members:
diff --git a/docs/source/plugin-development/plugin-parameters.rst b/docs/source/plugin-development/plugin-parameters.rst
index b7a4221..6dae857 100644
--- a/docs/source/plugin-development/plugin-parameters.rst
+++ b/docs/source/plugin-development/plugin-parameters.rst
@@ -72,7 +72,7 @@ Any plugin that has callable attributes ``add_options`` and
 Your ``add_options`` function should expect to receive an instance of
 |OptionManager|. An |OptionManager| instance behaves very similarly to
 :class:`optparse.OptionParser`. It, however, uses the layer that |Flake8| has
-developed on top of :mod:`optparse` to also handle configuration file parsing.
+developed on top of :mod:`argparse` to also handle configuration file parsing.
 :meth:`~flake8.options.manager.OptionManager.add_option` creates an |Option|
 which accepts the same parameters as :mod:`optparse` as well as three extra
 boolean parameters:
@@ -115,13 +115,13 @@ couple examples from |Flake8|. In each example, we will have
         '--max-line-length', type='int', metavar='n',
         default=defaults.MAX_LINE_LENGTH, parse_from_config=True,
         help='Maximum allowed line length for the entirety of this run. '
-             '(Default: %default)',
+             '(Default: %(default)s)',
     )
 
 Here we are adding the ``--max-line-length`` command-line option which is
 always an integer and will be parsed from the configuration file. Since we
-provide a default, we take advantage of :mod:`optparse`\ 's willingness to
-display that in the help text with ``%default``.
+provide a default, we take advantage of :mod:`argparse`\ 's willingness to
+display that in the help text with ``%(default)s``.
 
 .. code-block:: python
 
@@ -129,7 +129,7 @@ display that in the help text with ``%default``.
         '--select', metavar='errors', default='',
         parse_from_config=True, comma_separated_list=True,
         help='Comma-separated list of errors and warnings to enable.'
-             ' For example, ``--select=E4,E51,W234``. (Default: %default)',
+             ' For example, ``--select=E4,E51,W234``. (Default: %(default)s)',
     )
 
 In adding the ``--select`` command-line option, we're also indicating to the
@@ -143,7 +143,7 @@ as a comma-separated list.
         comma_separated_list=True, parse_from_config=True,
         normalize_paths=True,
         help='Comma-separated list of files or directories to exclude.'
-             '(Default: %default)',
+             '(Default: %(default)s)',
     )
 
 Finally, we show an option that uses all three extra flags. Values from
@@ -152,7 +152,7 @@ list, and then each item will be normalized.
 
 For information about other parameters to
 :meth:`~flake8.options.manager.OptionManager.add_option` refer to the
-documentation of :mod:`optparse`.
+documentation of :mod:`argparse`.
 
 
 Accessing Parsed Options
@@ -160,10 +160,10 @@ Accessing Parsed Options
 
 When a plugin has a callable ``parse_options`` attribute, |Flake8| will call
 it and attempt to provide the |OptionManager| instance, the parsed options
-which will be an instance of :class:`optparse.Values`, and the extra arguments
-that were not parsed by the |OptionManager|. If that fails, we will just pass
-the :class:`optparse.Values`. In other words, your ``parse_options``
-callable will have one of the following signatures:
+which will be an instance of :class:`argparse.Namespace`, and the extra
+arguments that were not parsed by the |OptionManager|. If that fails, we will
+just pass the :class:`argparse.Namespace`. In other words, your
+``parse_options`` callable will have one of the following signatures:
 
 .. code-block:: python
 
diff --git a/src/flake8/api/legacy.py b/src/flake8/api/legacy.py
index fd06a72..16a33f4 100644
--- a/src/flake8/api/legacy.py
+++ b/src/flake8/api/legacy.py
@@ -3,6 +3,7 @@
 Previously, users would import :func:`get_style_guide` from ``flake8.engine``.
 In 3.0 we no longer have an "engine" module but we maintain the API from it.
 """
+import argparse
 import logging
 import os.path
 
@@ -72,10 +73,10 @@ class StyleGuide(object):
         self._file_checker_manager = application.file_checker_manager
 
     @property
-    def options(self):
+    def options(self):  # type: () -> argparse.Namespace
         """Return application's options.
 
-        An instance of :class:`optparse.Values` containing parsed options.
+        An instance of :class:`argparse.Namespace` containing parsed options.
         """
         return self._application.options
 
diff --git a/src/flake8/checker.py b/src/flake8/checker.py
index 6170d88..a08f39c 100644
--- a/src/flake8/checker.py
+++ b/src/flake8/checker.py
@@ -367,7 +367,7 @@ class FileChecker(object):
         :param options:
             Parsed option values from config and command-line.
         :type options:
-            optparse.Values
+            argparse.Namespace
         """
         self.options = options
         self.filename = filename
diff --git a/src/flake8/formatting/base.py b/src/flake8/formatting/base.py
index 520dcbc..36dc905 100644
--- a/src/flake8/formatting/base.py
+++ b/src/flake8/formatting/base.py
@@ -1,7 +1,7 @@
 """The base class and interface for all formatting plugins."""
 from __future__ import print_function
 
-import optparse
+import argparse
 from typing import IO, List, Optional, Tuple
 
 if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
@@ -32,13 +32,13 @@ class BaseFormatter(object):
     """
 
     def __init__(self, options):
-        # type: (optparse.Values) -> None
+        # type: (argparse.Namespace) -> None
         """Initialize with the options parsed from config and cli.
 
         This also calls a hook, :meth:`after_init`, so subclasses do not need
         to call super to call this method.
 
-        :param optparse.Values options:
+        :param argparse.Namespace options:
             User specified configuration parsed from both configuration files
             and the command-line interface.
         """
diff --git a/src/flake8/main/application.py b/src/flake8/main/application.py
index 4bbee28..6e5373f 100644
--- a/src/flake8/main/application.py
+++ b/src/flake8/main/application.py
@@ -1,8 +1,8 @@
 """Module containing the application logic for Flake8."""
 from __future__ import print_function
 
+import argparse
 import logging
-import optparse
 import sys
 import time
 from typing import Dict, List, Optional, Set
@@ -52,8 +52,8 @@ class Application(object):
         )
         options.register_default_options(self.option_manager)
         #: The preliminary options parsed from CLI before plugins are loaded,
-        #: into a :class:`optparse.Values` instance
-        self.prelim_opts = None  # type: optparse.Values
+        #: into a :class:`argparse.Namespace` instance
+        self.prelim_opts = None  # type: argparse.Namespace
         #: The preliminary arguments parsed from CLI before plugins are loaded
         self.prelim_args = None  # type: List[str]
         #: The instance of :class:`flake8.options.config.ConfigFileFinder`
@@ -77,8 +77,8 @@ class Application(object):
         self.file_checker_manager = None  # type: checker.Manager
 
         #: The user-supplied options parsed into an instance of
-        #: :class:`optparse.Values`
-        self.options = None  # type: optparse.Values
+        #: :class:`argparse.Namespace`
+        self.options = None  # type: argparse.Namespace
         #: The left over arguments that were not parsed by
         #: :attr:`option_manager`
         self.args = None  # type: List[str]
@@ -117,7 +117,7 @@ class Application(object):
         # printing the version until we aggregate options from config files
         # and the command-line. First, let's clone our arguments on the CLI,
         # then we'll attempt to remove ``--version`` so that we can avoid
-        # triggering the "version" action in optparse. If it's not there, we
+        # triggering the "version" action in argparse. If it's not there, we
         # do not need to worry and we can continue. If it is, we successfully
         # defer printing the version until just a little bit later.
         # Similarly we have to defer printing the help text until later.
diff --git a/src/flake8/main/debug.py b/src/flake8/main/debug.py
index e02da6b..1d56189 100644
--- a/src/flake8/main/debug.py
+++ b/src/flake8/main/debug.py
@@ -1,41 +1,38 @@
 """Module containing the logic for our debugging logic."""
 from __future__ import print_function
 
+import argparse
 import json
 import platform
 
 import entrypoints
 
 
-def print_information(
-    option, option_string, value, parser, option_manager=None
-):
-    """Print debugging information used in bug reports.
+class DebugAction(argparse.Action):
+    """argparse action to print debug information."""
 
-    :param option:
-        The optparse Option instance.
-    :type option:
-        optparse.Option
-    :param str option_string:
-        The option name
-    :param value:
-        The value passed to the callback parsed from the command-line
-    :param parser:
-        The optparse OptionParser instance
-    :type parser:
-        optparse.OptionParser
-    :param option_manager:
-        The Flake8 OptionManager instance.
-    :type option_manager:
-        flake8.options.manager.OptionManager
-    """
-    if not option_manager.registered_plugins:
+    def __init__(self, *args, **kwargs):
+        """Initialize the action.
+
+        This takes an extra `option_manager` keyword argument which will be
+        used to delay response.
+        """
+        self._option_manager = kwargs.pop("option_manager")
+        super(DebugAction, self).__init__(*args, **kwargs)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        """Perform the argparse action for printing debug information."""
         # NOTE(sigmavirus24): Flake8 parses options twice. The first time, we
         # will not have any registered plugins. We can skip this one and only
         # take action on the second time we're called.
-        return
-    print(json.dumps(information(option_manager), indent=2, sort_keys=True))
-    raise SystemExit(False)
+        if not self._option_manager.registered_plugins:
+            return
+        print(
+            json.dumps(
+                information(self._option_manager), indent=2, sort_keys=True
+            )
+        )
+        raise SystemExit(0)
 
 
 def information(option_manager):
diff --git a/src/flake8/main/options.py b/src/flake8/main/options.py
index bef5630..75d2c8f 100644
--- a/src/flake8/main/options.py
+++ b/src/flake8/main/options.py
@@ -1,4 +1,6 @@
 """Contains the logic for all of the default options for Flake8."""
+import functools
+
 from flake8 import defaults
 from flake8.main import debug
 from flake8.main import vcs
@@ -83,7 +85,7 @@ def register_default_options(option_manager):
         parse_from_config=True,
         normalize_paths=True,
         help="Comma-separated list of files or directories to exclude."
-        " (Default: %default)",
+        " (Default: %(default)s)",
     )
 
     add_option(
@@ -103,7 +105,7 @@ def register_default_options(option_manager):
         parse_from_config=True,
         comma_separated_list=True,
         help="Only check for filenames matching the patterns in this comma-"
-        "separated list. (Default: %default)",
+        "separated list. (Default: %(default)s)",
     )
 
     add_option(
@@ -111,7 +113,7 @@ def register_default_options(option_manager):
         default="stdin",
         help="The name used when reporting errors from code passed via stdin."
         " This is useful for editors piping the file contents to flake8."
-        " (Default: %default)",
+        " (Default: %(default)s)",
     )
 
     # TODO(sigmavirus24): Figure out --first/--repeat
@@ -142,7 +144,7 @@ def register_default_options(option_manager):
         parse_from_config=True,
         comma_separated_list=True,
         help="Comma-separated list of errors and warnings to ignore (or skip)."
-        " For example, ``--ignore=E4,E51,W234``. (Default: %default)",
+        " For example, ``--ignore=E4,E51,W234``. (Default: %(default)s)",
     )
 
     add_option(
@@ -168,22 +170,22 @@ def register_default_options(option_manager):
 
     add_option(
         "--max-line-length",
-        type="int",
+        type=int,
         metavar="n",
         default=defaults.MAX_LINE_LENGTH,
         parse_from_config=True,
         help="Maximum allowed line length for the entirety of this run. "
-        "(Default: %default)",
+        "(Default: %(default)s)",
     )
 
     add_option(
         "--max-doc-length",
-        type="int",
+        type=int,
         metavar="n",
         default=None,
         parse_from_config=True,
         help="Maximum allowed doc line length for the entirety of this run. "
-        "(Default: %default)",
+        "(Default: %(default)s)",
     )
 
     add_option(
@@ -193,7 +195,7 @@ def register_default_options(option_manager):
         parse_from_config=True,
         comma_separated_list=True,
         help="Comma-separated list of errors and warnings to enable."
-        " For example, ``--select=E4,E51,W234``. (Default: %default)",
+        " For example, ``--select=E4,E51,W234``. (Default: %(default)s)",
     )
 
     add_option(
@@ -227,7 +229,6 @@ def register_default_options(option_manager):
         default="",
         parse_from_config=True,
         comma_separated_list=True,
-        type="string",
         help="Enable plugins and extensions that are otherwise disabled "
         "by default",
     )
@@ -240,10 +241,8 @@ def register_default_options(option_manager):
 
     add_option(
         "--install-hook",
-        action="callback",
-        type="choice",
+        action=vcs.InstallAction,
         choices=vcs.choices(),
-        callback=vcs.install,
         help="Install a hook that is run prior to a commit for the supported "
         "version control system.",
     )
@@ -251,21 +250,18 @@ def register_default_options(option_manager):
     add_option(
         "-j",
         "--jobs",
-        type="string",
         default="auto",
         parse_from_config=True,
         help="Number of subprocesses to use to run checks in parallel. "
         'This is ignored on Windows. The default, "auto", will '
         "auto-detect the number of processors available to use."
-        " (Default: %default)",
+        " (Default: %(default)s)",
     )
 
     add_option(
         "--output-file",
         default=None,
-        type="string",
         parse_from_config=True,
-        # callback=callbacks.redirect_stdout,
         help="Redirect report to a file.",
     )
 
@@ -316,8 +312,9 @@ def register_default_options(option_manager):
 
     add_option(
         "--bug-report",
-        action="callback",
-        callback=debug.print_information,
-        callback_kwargs={"option_manager": option_manager},
+        action=functools.partial(
+            debug.DebugAction, option_manager=option_manager
+        ),
+        nargs=0,
         help="Print information necessary when preparing a bug report",
     )
diff --git a/src/flake8/main/vcs.py b/src/flake8/main/vcs.py
index 398643c..cbe6972 100644
--- a/src/flake8/main/vcs.py
+++ b/src/flake8/main/vcs.py
@@ -1,4 +1,6 @@
 """Module containing some of the logic for our VCS installation logic."""
+import argparse
+
 from flake8 import exceptions as exc
 from flake8.main import git
 from flake8.main import mercurial
@@ -11,24 +13,23 @@ from flake8.main import mercurial
 _INSTALLERS = {"git": git.install, "mercurial": mercurial.install}
 
 
-def install(option, option_string, value, parser):
-    """Determine which version control hook to install.
-
-    For more information about the callback signature, see:
-    https://docs.python.org/3/library/optparse.html#optparse-option-callbacks
-    """
-    installer = _INSTALLERS[value]
-    errored = False
-    successful = False
-    try:
-        successful = installer()
-    except exc.HookInstallationError as hook_error:
-        print(str(hook_error))
-        errored = True
-
-    if not successful:
-        print("Could not find the {0} directory".format(value))
-    raise SystemExit(not successful and errored)
+class InstallAction(argparse.Action):
+    """argparse action to run the hook installation."""
+
+    def __call__(self, parser, namespace, value, option_string=None):
+        """Perform the argparse action for installing vcs hooks."""
+        installer = _INSTALLERS[value]
+        errored = False
+        successful = False
+        try:
+            successful = installer()
+        except exc.HookInstallationError as hook_error:
+            print(str(hook_error))
+            errored = True
+
+        if not successful:
+            print("Could not find the {0} directory".format(value))
+        raise SystemExit(not successful and errored)
 
 
 def choices():
diff --git a/src/flake8/options/aggregator.py b/src/flake8/options/aggregator.py
index 304f53c..1b9c60c 100644
--- a/src/flake8/options/aggregator.py
+++ b/src/flake8/options/aggregator.py
@@ -21,13 +21,13 @@ def aggregate_options(manager, config_finder, arglist=None, values=None):
         The list of arguments to pass to ``manager.parse_args``. In most cases
         this will be None so ``parse_args`` uses ``sys.argv``. This is mostly
         available to make testing easier.
-    :param optparse.Values values:
+    :param argparse.Namespace values:
         Previously parsed set of parsed options.
     :returns:
         Tuple of the parsed options and extra arguments returned by
         ``manager.parse_args``.
     :rtype:
-        tuple(optparse.Values, list)
+        tuple(argparse.Namespace, list)
     """
     # Get defaults from the option parser
     default_values, _ = manager.parse_args([], values=values)
diff --git a/src/flake8/options/config.py b/src/flake8/options/config.py
index 2af8cc8..0a43625 100644
--- a/src/flake8/options/config.py
+++ b/src/flake8/options/config.py
@@ -167,9 +167,6 @@ class MergedConfigParser(object):
     dictionaries with the parsed values.
     """
 
-    #: Set of types that should use the
-    #: :meth:`~configparser.RawConfigParser.getint` method.
-    GETINT_TYPES = {"int", "count"}
     #: Set of actions that should use the
     #: :meth:`~configparser.RawConfigParser.getbool` method.
     GETBOOL_ACTIONS = {"store_true", "store_false"}
@@ -216,10 +213,7 @@ class MergedConfigParser(object):
 
             # Use the appropriate method to parse the config value
             method = config_parser.get
-            if (
-                option.type in self.GETINT_TYPES
-                or option.action in self.GETINT_TYPES
-            ):
+            if option.type is int or option.action == "count":
                 method = config_parser.getint
             elif option.action in self.GETBOOL_ACTIONS:
                 method = config_parser.getboolean
diff --git a/src/flake8/options/manager.py b/src/flake8/options/manager.py
index cf94927..219e0ad 100644
--- a/src/flake8/options/manager.py
+++ b/src/flake8/options/manager.py
@@ -1,55 +1,100 @@
 """Option handling and Option management logic."""
+import argparse
 import collections
+import functools
 import logging
-import optparse  # pylint: disable=deprecated-module
-from typing import Dict, List, Optional, Set
+from typing import Any, Dict, List, Optional, Set
 
 from flake8 import utils
 
 LOG = logging.getLogger(__name__)
 
+_NOARG = object()
+
+
+class _CallbackAction(argparse.Action):
+    """Shim for optparse-style callback actions."""
+
+    def __init__(self, *args, **kwargs):
+        self._callback = kwargs.pop("callback")
+        self._callback_args = kwargs.pop("callback_args", ())
+        self._callback_kwargs = kwargs.pop("callback_kwargs", {})
+        super(_CallbackAction, self).__init__(*args, **kwargs)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        if not values:
+            values = None
+        elif isinstance(values, list) and len(values) > 1:
+            values = tuple(values)
+        self._callback(
+            self,
+            option_string,
+            values,
+            parser,
+            *self._callback_args,
+            **self._callback_kwargs
+        )
+
+
+def _flake8_normalize(value, *args, **kwargs):
+    comma_separated_list = kwargs.pop("comma_separated_list", False)
+    normalize_paths = kwargs.pop("normalize_paths", False)
+    if kwargs:
+        raise TypeError("Unexpected keyword args: {}".format(kwargs))
+
+    if comma_separated_list and isinstance(value, utils.string_types):
+        value = utils.parse_comma_separated_list(value)
+
+    if normalize_paths:
+        if isinstance(value, list):
+            value = utils.normalize_paths(value, *args)
+        else:
+            value = utils.normalize_path(value, *args)
+
+    return value
+
 
 class Option(object):
-    """Our wrapper around an optparse.Option object to add features."""
+    """Our wrapper around an argparse argument parsers to add features."""
 
     def __init__(
         self,
-        short_option_name=None,
-        long_option_name=None,
+        short_option_name=_NOARG,
+        long_option_name=_NOARG,
         # Options below here are taken from the optparse.Option class
-        action=None,
-        default=None,
-        type=None,
-        dest=None,
-        nargs=None,
-        const=None,
-        choices=None,
-        callback=None,
-        callback_args=None,
-        callback_kwargs=None,
-        help=None,
-        metavar=None,
+        action=_NOARG,
+        default=_NOARG,
+        type=_NOARG,
+        dest=_NOARG,
+        nargs=_NOARG,
+        const=_NOARG,
+        choices=_NOARG,
+        help=_NOARG,
+        metavar=_NOARG,
+        # deprecated optparse-only options
+        callback=_NOARG,
+        callback_args=_NOARG,
+        callback_kwargs=_NOARG,
+        # Options below are taken from argparse.ArgumentParser.add_argument
+        required=_NOARG,
         # Options below here are specific to Flake8
         parse_from_config=False,
         comma_separated_list=False,
         normalize_paths=False,
     ):
-        """Initialize an Option instance wrapping optparse.Option.
+        """Initialize an Option instance.
 
-        The following are all passed directly through to optparse.
+        The following are all passed directly through to argparse.
 
         :param str short_option_name:
             The short name of the option (e.g., ``-x``). This will be the
-            first argument passed to :class:`~optparse.Option`.
+            first argument passed to ``ArgumentParser.add_argument``
         :param str long_option_name:
             The long name of the option (e.g., ``--xtra-long-option``). This
-            will be the second argument passed to :class:`~optparse.Option`.
-        :param str action:
-            Any action allowed by :mod:`optparse`.
+            will be the second argument passed to
+            ``ArgumentParser.add_argument``
         :param default:
             Default value of the option.
-        :param type:
-            Any type allowed by :mod:`optparse`.
         :param dest:
             Attribute name to store parsed option value as.
         :param nargs:
@@ -59,16 +104,33 @@ class Option(object):
             conjuntion with ``action="store_const"``.
         :param iterable choices:
             Possible values for the option.
-        :param callable callback:
-            Callback used if the action is ``"callback"``.
-        :param iterable callback_args:
-            Additional positional arguments to the callback callable.
-        :param dictionary callback_kwargs:
-            Keyword arguments to the callback callable.
         :param str help:
             Help text displayed in the usage information.
         :param str metavar:
             Name to use instead of the long option name for help text.
+        :param bool required:
+            Whether this option is required or not.
+
+        The following options may be passed directly through to :mod:`argparse`
+        but may need some massaging.
+
+        :param type:
+            A callable to normalize the type (as is the case in
+            :mod:`argparse`).  Deprecated: you can also pass through type
+            strings such as ``'int'`` which are handled by :mod:`optparse`.
+        :param str action:
+            Any action allowed by :mod:`argparse`.  Deprecated: this also
+            understands the ``action='callback'`` action from :mod:`optparse`.
+        :param callable callback:
+            Callback used if the action is ``"callback"``.  Deprecated: please
+            use ``action=`` instead.
+        :param iterable callback_args:
+            Additional positional arguments to the callback callable.
+            Deprecated: please use ``action=`` instead (probably with
+            ``functools.partial``).
+        :param dictionary callback_kwargs:
+            Keyword arguments to the callback callable. Deprecated: please
+            use ``action=`` instead (probably with ``functools.partial``).
 
         The following parameters are for Flake8's option handling alone.
 
@@ -81,16 +143,66 @@ class Option(object):
             Whether the option is expecting a path or list of paths and should
             attempt to normalize the paths to absolute paths.
         """
+        if long_option_name is _NOARG and short_option_name.startswith("--"):
+            short_option_name, long_option_name = _NOARG, short_option_name
+
+        # optparse -> argparse `%default` => `%(default)s`
+        if help is not _NOARG and "%default" in help:
+            LOG.warning(
+                "option %s: please update `help=` text to use %%(default)s "
+                "instead of %%default -- this will be an error in the future",
+                long_option_name,
+            )
+            help = help.replace("%default", "%(default)s")
+
+        # optparse -> argparse for `callback`
+        if action == "callback":
+            LOG.warning(
+                "option %s: please update from optparse `action='callback'` "
+                "to argparse action classes -- this will be an error in the "
+                "future",
+                long_option_name,
+            )
+            action = _CallbackAction
+            if type is _NOARG:
+                nargs = 0
+
+        # optparse -> argparse for `type`
+        if isinstance(type, utils.string_types):
+            LOG.warning(
+                "option %s: please update from optparse string `type=` to "
+                "argparse callable `type=` -- this will be an error in the "
+                "future"
+            )
+            type = {
+                "int": int,
+                "long": int,
+                "string": str,
+                "float": float,
+                "complex": complex,
+                "choice": _NOARG,
+            }[type]
+
+        # flake8 special type normalization
+        if comma_separated_list or normalize_paths:
+            type = functools.partial(
+                _flake8_normalize,
+                comma_separated_list=comma_separated_list,
+                normalize_paths=normalize_paths,
+            )
+
         self.short_option_name = short_option_name
         self.long_option_name = long_option_name
         self.option_args = [
-            x for x in (short_option_name, long_option_name) if x is not None
+            x
+            for x in (short_option_name, long_option_name)
+            if x is not _NOARG
         ]
         self.option_kwargs = {
             "action": action,
             "default": default,
             "type": type,
-            "dest": self._make_dest(dest),
+            "dest": dest,
             "nargs": nargs,
             "const": const,
             "choices": choices,
@@ -111,7 +223,7 @@ class Option(object):
 
         self.config_name = None  # type: Optional[str]
         if parse_from_config:
-            if not long_option_name:
+            if long_option_name is _NOARG:
                 raise ValueError(
                     "When specifying parse_from_config=True, "
                     "a long_option_name must also be specified."
@@ -120,25 +232,20 @@ class Option(object):
 
         self._opt = None
 
-    def __repr__(self):  # noqa: D105
-        return (
-            "Option({0}, {1}, action={action}, default={default}, "
-            "dest={dest}, type={type}, callback={callback}, help={help},"
-            " callback={callback}, callback_args={callback_args}, "
-            "callback_kwargs={callback_kwargs}, metavar={metavar})"
-        ).format(
-            self.short_option_name,
-            self.long_option_name,
-            **self.option_kwargs
-        )
-
-    def _make_dest(self, dest):
-        if dest:
-            return dest
+    @property
+    def filtered_option_kwargs(self):  # type: () -> Dict[str, Any]
+        """Return any actually-specified arguments."""
+        return {
+            k: v for k, v in self.option_kwargs.items() if v is not _NOARG
+        }
 
-        if self.long_option_name:
-            return self.long_option_name[2:].replace("-", "_")
-        return self.short_option_name[1]
+    def __repr__(self):  # noqa: D105
+        parts = []
+        for arg in self.option_args:
+            parts.append(arg)
+        for k, v in self.filtered_option_kwargs.items():
+            parts.append("{}={!r}".format(k, v))
+        return "Option({})".format(", ".join(parts))
 
     def normalize(self, value, *normalize_args):
         """Normalize the value based on the option configuration."""
@@ -158,11 +265,11 @@ class Option(object):
     def normalize_from_setuptools(self, value):
         """Normalize the value received from setuptools."""
         value = self.normalize(value)
-        if self.type == "int" or self.action == "count":
+        if self.type is int or self.action == "count":
             return int(value)
-        elif self.type == "float":
+        elif self.type is float:
             return float(value)
-        elif self.type == "complex":
+        elif self.type is complex:
             return complex(value)
         if self.action in ("store_true", "store_false"):
             value = str(value).upper()
@@ -172,13 +279,14 @@ class Option(object):
                 return False
         return value
 
+    def to_argparse(self):
+        """Convert a Flake8 Option to argparse ``add_argument`` arguments."""
+        return self.option_args, self.filtered_option_kwargs
+
+    @property
     def to_optparse(self):
-        """Convert a Flake8 Option to an optparse Option."""
-        if self._opt is None:
-            self._opt = optparse.Option(
-                *self.option_args, **self.option_kwargs
-            )
-        return self._opt
+        """No longer functional."""
+        raise AttributeError("to_optparse: flake8 now uses argparse")
 
 
 PluginVersion = collections.namedtuple(
@@ -190,7 +298,10 @@ class OptionManager(object):
     """Manage Options and OptionParser while adding post-processing."""
 
     def __init__(
-        self, prog=None, version=None, usage="%prog [options] file file ..."
+        self,
+        prog=None,
+        version=None,
+        usage="%(prog)s [options] file file ...",
     ):
         """Initialize an instance of an OptionManager.
 
@@ -201,9 +312,11 @@ class OptionManager(object):
         :param str usage:
             Basic usage string used by the OptionParser.
         """
-        self.parser = optparse.OptionParser(
-            prog=prog, version=version, usage=usage
+        self.parser = argparse.ArgumentParser(prog=prog, usage=usage)
+        self.version_action = self.parser.add_argument(
+            "--version", action="version", version=version
         )
+        self.parser.add_argument("filenames", nargs="*", metavar="filename")
         self.config_options_dict = {}  # type: Dict[str, Option]
         self.options = []  # type: List[Option]
         self.program_name = prog
@@ -226,12 +339,11 @@ class OptionManager(object):
         .. note::
 
             ``short_option_name`` and ``long_option_name`` may be specified
-            positionally as they are with optparse normally.
+            positionally as they are with argparse normally.
         """
-        if len(args) == 1 and args[0].startswith("--"):
-            args = (None, args[0])
         option = Option(*args, **kwargs)
-        self.parser.add_option(option.to_optparse())
+        option_args, option_kwargs = option.to_argparse()
+        self.parser.add_argument(*option_args, **option_kwargs)
         self.options.append(option)
         if option.parse_from_config:
             name = option.config_name
@@ -289,12 +401,8 @@ class OptionManager(object):
 
     def update_version_string(self):
         """Update the flake8 version string."""
-        self.parser.version = (
-            self.version
-            + " ("
-            + self.generate_versions()
-            + ") "
-            + utils.get_python_version()
+        self.version_action.version = "{} ({}) {}".format(
+            self.version, self.generate_versions(), utils.get_python_version()
         )
 
     def generate_epilog(self):
@@ -304,18 +412,13 @@ class OptionManager(object):
             plugin_version_format
         )
 
-    def _normalize(self, options):
-        for option in self.options:
-            old_value = getattr(options, option.dest)
-            setattr(options, option.dest, option.normalize(old_value))
-
     def parse_args(self, args=None, values=None):
         """Proxy to calling the OptionParser's parse_args method."""
         self.generate_epilog()
         self.update_version_string()
-        options, xargs = self.parser.parse_args(args, values)
-        self._normalize(options)
-        return options, xargs
+        args = self.parser.parse_args(args, values)
+        # TODO: refactor callers to not need this
+        return args, args.filenames
 
     def parse_known_args(self, args=None, values=None):
         """Parse only the known arguments from the argument values.
@@ -325,33 +428,8 @@ class OptionManager(object):
         """
         self.generate_epilog()
         self.update_version_string()
-        # Taken from optparse.OptionParser.parse_args
-        rargs = self.parser._get_args(args)
-        if values is None:
-            values = self.parser.get_default_values()
-
-        self.parser.rargs = rargs
-        largs = []  # type: List[str]
-        self.parser.values = values
-
-        while rargs:
-            # NOTE(sigmavirus24): If we only care about *known* options, then
-            # we should just shift the bad option over to the largs list and
-            # carry on.
-            # Unfortunately, we need to rely on a private method here.
-            try:
-                self.parser._process_args(largs, rargs, values)
-            except (
-                optparse.BadOptionError,
-                optparse.OptionValueError,
-            ) as err:
-                # TODO: https://gitlab.com/pycqa/flake8/issues/541
-                largs.append(err.opt_str)  # type: ignore
-
-        args = largs + rargs
-        options, xargs = self.parser.check_values(values, args)
-        self._normalize(options)
-        return options, xargs
+        args, rest = self.parser.parse_known_args(args, values)
+        return args, rest
 
     def register_plugin(self, name, version, local=False):
         """Register a plugin relying on the OptionManager.
diff --git a/src/flake8/plugins/pyflakes.py b/src/flake8/plugins/pyflakes.py
index 018d1c9..b216b62 100644
--- a/src/flake8/plugins/pyflakes.py
+++ b/src/flake8/plugins/pyflakes.py
@@ -118,7 +118,6 @@ class FlakesChecker(pyflakes.checker.Checker):
             comma_separated_list=True,
             normalize_paths=True,
             help="Run doctests only on these files",
-            type="string",
         )
         parser.add_option(
             "--exclude-from-doctest",
@@ -128,7 +127,6 @@ class FlakesChecker(pyflakes.checker.Checker):
             comma_separated_list=True,
             normalize_paths=True,
             help="Skip these files when running doctests",
-            type="string",
         )
 
     @classmethod
diff --git a/src/flake8/style_guide.py b/src/flake8/style_guide.py
index b644f8b..8d3c8cf 100644
--- a/src/flake8/style_guide.py
+++ b/src/flake8/style_guide.py
@@ -349,7 +349,7 @@ class StyleGuideManager(object):
         :param options:
             The original options parsed from the CLI and config file.
         :type options:
-            :class:`~optparse.Values`
+            :class:`~argparse.Namespace`
         :returns:
             A copy of the default style guide with overridden values.
         :rtype:
diff --git a/tests/integration/test_main.py b/tests/integration/test_main.py
index ccc70e1..001f1ff 100644
--- a/tests/integration/test_main.py
+++ b/tests/integration/test_main.py
@@ -1,10 +1,18 @@
 """Integration tests for the main entrypoint of flake8."""
+import json
 import os
 
 import mock
+import pytest
 
 from flake8 import utils
-from flake8.main import application
+from flake8.main import cli
+
+
+def _call_main(argv, retv=0):
+    with pytest.raises(SystemExit) as excinfo:
+        cli.main(argv)
+    assert excinfo.value.code == retv
 
 
 def test_diff_option(tmpdir, capsys):
@@ -36,9 +44,7 @@ index d64ac39..7d943de 100644
     with mock.patch.object(utils, 'stdin_get_value', return_value=diff):
         with tmpdir.as_cwd():
             tmpdir.join('t.py').write(t_py_contents)
-
-            app = application.Application()
-            app.run(['--diff'])
+            _call_main(['--diff'], retv=1)
 
     out, err = capsys.readouterr()
     assert out == "t.py:8:1: F821 undefined name 'y'\n"
@@ -49,9 +55,7 @@ def test_statistics_option(tmpdir, capsys):
     """Ensure that `flake8 --statistics` works."""
     with tmpdir.as_cwd():
         tmpdir.join('t.py').write('import os\nimport sys\n')
-
-        app = application.Application()
-        app.run(['--statistics', 't.py'])
+        _call_main(['--statistics', 't.py'], retv=1)
 
     out, err = capsys.readouterr()
     assert out == '''\
@@ -68,7 +72,7 @@ def test_extend_exclude(tmpdir, capsys):
         tmpdir.mkdir(d).join('t.py').write('import os\nimport sys\n')
 
     with tmpdir.as_cwd():
-        application.Application().run(['--extend-exclude=vendor,legacy'])
+        _call_main(['--extend-exclude=vendor,legacy'], retv=1)
 
     out, err = capsys.readouterr()
     expected_out = '''\
@@ -90,9 +94,7 @@ per-file-ignores =
 
     with tmpdir.as_cwd():
         tmpdir.join('setup.cfg').write(setup_cfg)
-
-        app = application.Application()
-        app.run(['.'])
+        _call_main(['.'], retv=1)
 
     out, err = capsys.readouterr()
     assert out == '''\
@@ -111,10 +113,16 @@ def test_tokenization_error_but_not_syntax_error(tmpdir, capsys):
     with tmpdir.as_cwd():
         # this is a crash in the tokenizer, but not in the ast
         tmpdir.join('t.py').write("b'foo' \\\n")
-
-        app = application.Application()
-        app.run(['t.py'])
+        _call_main(['t.py'], retv=1)
 
     out, err = capsys.readouterr()
     assert out == 't.py:1:1: E902 TokenError: EOF in multi-line statement\n'
     assert err == ''
+
+
+def test_bug_report_successful(capsys):
+    """Test that --bug-report does not crash."""
+    _call_main(['--bug-report'])
+    out, err = capsys.readouterr()
+    assert json.loads(out)
+    assert err == ''
diff --git a/tests/unit/conftest.py b/tests/unit/conftest.py
index d570564..3541ec3 100644
--- a/tests/unit/conftest.py
+++ b/tests/unit/conftest.py
@@ -1,5 +1,5 @@
 """Shared fixtures between unit tests."""
-import optparse
+import argparse
 
 import pytest
 
@@ -11,7 +11,7 @@ def options_from(**kwargs):
     kwargs.setdefault('max_doc_length', None)
     kwargs.setdefault('verbose', False)
     kwargs.setdefault('stdin_display_name', 'stdin')
-    return optparse.Values(kwargs)
+    return argparse.Namespace(**kwargs)
 
 
 @pytest.fixture
diff --git a/tests/unit/test_application.py b/tests/unit/test_application.py
index cb8372b..8e5c9d5 100644
--- a/tests/unit/test_application.py
+++ b/tests/unit/test_application.py
@@ -1,5 +1,5 @@
 """Tests for the Application class."""
-import optparse
+import argparse
 import sys
 
 import mock
@@ -9,12 +9,12 @@ from flake8.main import application as app
 
 
 def options(**kwargs):
-    """Generate optparse.Values for our Application."""
+    """Generate argparse.Namespace for our Application."""
     kwargs.setdefault('verbose', 0)
     kwargs.setdefault('output_file', None)
     kwargs.setdefault('count', False)
     kwargs.setdefault('exit_zero', False)
-    return optparse.Values(kwargs)
+    return argparse.Namespace(**kwargs)
 
 
 @pytest.fixture
diff --git a/tests/unit/test_base_formatter.py b/tests/unit/test_base_formatter.py
index ee589aa..7a85554 100644
--- a/tests/unit/test_base_formatter.py
+++ b/tests/unit/test_base_formatter.py
@@ -1,5 +1,5 @@
 """Tests for the BaseFormatter object."""
-import optparse
+import argparse
 
 import mock
 import pytest
@@ -9,10 +9,10 @@ from flake8.formatting import base
 
 
 def options(**kwargs):
-    """Create an optparse.Values instance."""
+    """Create an argparse.Namespace instance."""
     kwargs.setdefault('output_file', None)
     kwargs.setdefault('tee', False)
-    return optparse.Values(kwargs)
+    return argparse.Namespace(**kwargs)
 
 
 @pytest.mark.parametrize('filename', [None, 'out.txt'])
diff --git a/tests/unit/test_debug.py b/tests/unit/test_debug.py
index 2b7995d..c973abb 100644
--- a/tests/unit/test_debug.py
+++ b/tests/unit/test_debug.py
@@ -73,9 +73,10 @@ def test_information(system, pyversion, pyimpl):
 def test_print_information_no_plugins(dumps, information, print_mock):
     """Verify we print and exit only when we have plugins."""
     option_manager = mock.Mock(registered_plugins=set())
-    assert debug.print_information(
-        None, None, None, None, option_manager=option_manager,
-    ) is None
+    action = debug.DebugAction(
+        "--bug-report", dest="bug_report", option_manager=option_manager,
+    )
+    assert action(None, None, None, None) is None
     assert dumps.called is False
     assert information.called is False
     assert print_mock.called is False
@@ -91,10 +92,11 @@ def test_print_information(dumps, information, print_mock):
         manager.PluginVersion('mccabe', '0.5.9', False),
     ]
     option_manager = mock.Mock(registered_plugins=set(plugins))
+    action = debug.DebugAction(
+        "--bug-report", dest="bug_report", option_manager=option_manager,
+    )
     with pytest.raises(SystemExit):
-        debug.print_information(
-            None, None, None, None, option_manager=option_manager,
-        )
+        action(None, None, None, None)
     print_mock.assert_called_once_with('{}')
     dumps.assert_called_once_with({}, indent=2, sort_keys=True)
     information.assert_called_once_with(option_manager)
diff --git a/tests/unit/test_decision_engine.py b/tests/unit/test_decision_engine.py
index 635c9d8..7d92309 100644
--- a/tests/unit/test_decision_engine.py
+++ b/tests/unit/test_decision_engine.py
@@ -1,5 +1,5 @@
 """Tests for the flake8.style_guide.DecisionEngine class."""
-import optparse
+import argparse
 
 import pytest
 
@@ -8,14 +8,14 @@ from flake8 import style_guide
 
 
 def create_options(**kwargs):
-    """Create and return an instance of optparse.Values."""
+    """Create and return an instance of argparse.Namespace."""
     kwargs.setdefault('select', [])
     kwargs.setdefault('extended_default_select', [])
     kwargs.setdefault('ignore', [])
     kwargs.setdefault('extend_ignore', [])
     kwargs.setdefault('disable_noqa', False)
     kwargs.setdefault('enable_extensions', [])
-    return optparse.Values(kwargs)
+    return argparse.Namespace(**kwargs)
 
 
 @pytest.mark.parametrize('ignore_list,extend_ignore,error_code', [
diff --git a/tests/unit/test_filenameonly_formatter.py b/tests/unit/test_filenameonly_formatter.py
index b423ee3..8d0c88f 100644
--- a/tests/unit/test_filenameonly_formatter.py
+++ b/tests/unit/test_filenameonly_formatter.py
@@ -1,15 +1,15 @@
 """Tests for the FilenameOnly formatter object."""
-import optparse
+import argparse
 
 from flake8 import style_guide
 from flake8.formatting import default
 
 
 def options(**kwargs):
-    """Create an optparse.Values instance."""
+    """Create an argparse.Namespace instance."""
     kwargs.setdefault('output_file', None)
     kwargs.setdefault('tee', False)
-    return optparse.Values(kwargs)
+    return argparse.Namespace(**kwargs)
 
 
 def test_caches_filenames_already_printed():
diff --git a/tests/unit/test_merged_config_parser.py b/tests/unit/test_merged_config_parser.py
index 37d5e6f..1112a0d 100644
--- a/tests/unit/test_merged_config_parser.py
+++ b/tests/unit/test_merged_config_parser.py
@@ -215,7 +215,7 @@ def test_parsed_hyphenated_and_underscored_names(
     max_line_length in our config files.
     """
     optmanager.add_option('--max-line-length', parse_from_config=True,
-                          type='int')
+                          type=int)
     optmanager.add_option('--enable-extensions', parse_from_config=True,
                           comma_separated_list=True)
     parser = config.MergedConfigParser(optmanager, config_finder)
diff --git a/tests/unit/test_nothing_formatter.py b/tests/unit/test_nothing_formatter.py
index a1fd683..85a2e76 100644
--- a/tests/unit/test_nothing_formatter.py
+++ b/tests/unit/test_nothing_formatter.py
@@ -1,15 +1,15 @@
 """Tests for the Nothing formatter obbject."""
-import optparse
+import argparse
 
 from flake8 import style_guide
 from flake8.formatting import default
 
 
 def options(**kwargs):
-    """Create an optparse.Values instance."""
+    """Create an argparse.Namespace instance."""
     kwargs.setdefault('output_file', None)
     kwargs.setdefault('tee', False)
-    return optparse.Values(kwargs)
+    return argparse.Namespace(**kwargs)
 
 
 def test_format_returns_nothing():
diff --git a/tests/unit/test_option.py b/tests/unit/test_option.py
index e931d13..d4607b3 100644
--- a/tests/unit/test_option.py
+++ b/tests/unit/test_option.py
@@ -1,12 +1,14 @@
 """Unit tests for flake8.options.manager.Option."""
+import functools
+
 import mock
 import pytest
 
 from flake8.options import manager
 
 
-def test_to_optparse():
-    """Test conversion to an optparse.Option class."""
+def test_to_argparse():
+    """Test conversion to an argparse arguments."""
     opt = manager.Option(
         short_option_name='-t',
         long_option_name='--test',
@@ -17,45 +19,26 @@ def test_to_optparse():
     assert opt.normalize_paths is True
     assert opt.parse_from_config is True
 
-    optparse_opt = opt.to_optparse()
-    assert not hasattr(optparse_opt, 'parse_from_config')
-    assert not hasattr(optparse_opt, 'normalize_paths')
-    assert optparse_opt.action == 'count'
+    args, kwargs = opt.to_argparse()
+    assert args == ['-t', '--test']
+    assert kwargs == {'action': 'count', 'type': mock.ANY}
+    assert isinstance(kwargs['type'], functools.partial)
 
 
-@pytest.mark.parametrize('opttype,str_val,expected', [
-    ('float', '2', 2.0),
-    ('complex', '2', (2 + 0j)),
-])
-def test_to_support_optparses_standard_types(opttype, str_val, expected):
-    """Show that optparse converts float and complex types correctly."""
-    opt = manager.Option('-t', '--test', type=opttype)
-    assert opt.normalize_from_setuptools(str_val) == expected
+def test_to_optparse():
+    """Test that .to_optparse() produces a useful error message."""
+    with pytest.raises(AttributeError) as excinfo:
+        manager.Option('--foo').to_optparse()
+    msg, = excinfo.value.args
+    assert msg == 'to_optparse: flake8 now uses argparse'
 
 
-@mock.patch('optparse.Option')
-def test_to_optparse_creates_an_option_as_we_expect(Option):  # noqa: N803
-    """Show that we pass all keyword args to optparse.Option."""
+def test_to_argparse_creates_an_option_as_we_expect():
+    """Show that we pass all keyword args to argparse."""
     opt = manager.Option('-t', '--test', action='count')
-    opt.to_optparse()
-    option_kwargs = {
-        'action': 'count',
-        'default': None,
-        'type': None,
-        'dest': 'test',
-        'nargs': None,
-        'const': None,
-        'choices': None,
-        'callback': None,
-        'callback_args': None,
-        'callback_kwargs': None,
-        'help': None,
-        'metavar': None,
-    }
-
-    Option.assert_called_once_with(
-        '-t', '--test', **option_kwargs
-    )
+    args, kwargs = opt.to_argparse()
+    assert args == ['-t', '--test']
+    assert kwargs == {'action': 'count'}
 
 
 def test_config_name_generation():
diff --git a/tests/unit/test_option_manager.py b/tests/unit/test_option_manager.py
index df1f9a2..ebcd9e7 100644
--- a/tests/unit/test_option_manager.py
+++ b/tests/unit/test_option_manager.py
@@ -1,5 +1,5 @@
 """Unit tests for flake.options.manager.OptionManager."""
-import optparse
+import argparse
 import os
 
 import mock
@@ -19,8 +19,7 @@ def optmanager():
 
 def test_option_manager_creates_option_parser(optmanager):
     """Verify that a new manager creates a new parser."""
-    assert optmanager.parser is not None
-    assert isinstance(optmanager.parser, optparse.OptionParser) is True
+    assert isinstance(optmanager.parser, argparse.ArgumentParser)
 
 
 def test_add_option_short_option_only(optmanager):
@@ -38,7 +37,7 @@ def test_add_option_long_option_only(optmanager):
     assert optmanager.config_options_dict == {}
 
     optmanager.add_option('--long', help='Test long opt')
-    assert optmanager.options[0].short_option_name is None
+    assert optmanager.options[0].short_option_name is manager._NOARG
     assert optmanager.options[0].long_option_name == '--long'
 
 
@@ -171,7 +170,7 @@ def test_generate_versions_with_format_string(optmanager):
 def test_update_version_string(optmanager):
     """Verify we update the version string idempotently."""
     assert optmanager.version == TEST_VERSION
-    assert optmanager.parser.version == TEST_VERSION
+    assert optmanager.version_action.version == TEST_VERSION
 
     optmanager.registered_plugins = [
         manager.PluginVersion('Testing 100', '0.0.0', False),
@@ -182,7 +181,7 @@ def test_update_version_string(optmanager):
     optmanager.update_version_string()
 
     assert optmanager.version == TEST_VERSION
-    assert (optmanager.parser.version == TEST_VERSION
+    assert (optmanager.version_action.version == TEST_VERSION
             + ' (Testing 100: 0.0.0, Testing 101: 0.0.0, Testing 300: 0.0.0) '
             + utils.get_python_version())
 
@@ -211,9 +210,7 @@ def test_extend_default_ignore(optmanager):
     assert optmanager.extended_default_ignore == set()
 
     optmanager.extend_default_ignore(['T100', 'T101', 'T102'])
-    assert optmanager.extended_default_ignore == {'T100',
-                                                  'T101',
-                                                  'T102'}
+    assert optmanager.extended_default_ignore == {'T100', 'T101', 'T102'}
 
 
 def test_parse_known_args(optmanager):
@@ -222,3 +219,91 @@ def test_parse_known_args(optmanager):
         optmanager.parse_known_args(['--max-complexity', '5'])
 
     assert sysexit.called is False
+
+
+def test_optparse_normalize_callback_option_legacy(optmanager):
+    """Test the optparse shim for `callback=`."""
+    callback_foo = mock.Mock()
+    optmanager.add_option(
+        '--foo',
+        action='callback',
+        callback=callback_foo,
+        callback_args=(1, 2),
+        callback_kwargs={'a': 'b'},
+    )
+    callback_bar = mock.Mock()
+    optmanager.add_option(
+        '--bar',
+        action='callback',
+        type='string',
+        callback=callback_bar,
+    )
+    callback_baz = mock.Mock()
+    optmanager.add_option(
+        '--baz',
+        action='callback',
+        type='string',
+        nargs=2,
+        callback=callback_baz,
+    )
+
+    optmanager.parse_args(['--foo', '--bar', 'bararg', '--baz', '1', '2'])
+
+    callback_foo.assert_called_once_with(
+        mock.ANY,  # the option / action instance
+        '--foo',
+        None,
+        mock.ANY,  # the OptionParser / ArgumentParser
+        1,
+        2,
+        a='b',
+    )
+    callback_bar.assert_called_once_with(
+        mock.ANY,  # the option / action instance
+        '--bar',
+        'bararg',
+        mock.ANY,  # the OptionParser / ArgumentParser
+    )
+    callback_baz.assert_called_once_with(
+        mock.ANY,  # the option / action instance
+        '--baz',
+        ('1', '2'),
+        mock.ANY,  # the OptionParser / ArgumentParser
+    )
+
+
+@pytest.mark.parametrize(
+    ('type_s', 'input_val', 'expected'),
+    (
+        ('int', '5', 5),
+        ('long', '6', 6),
+        ('string', 'foo', 'foo'),
+        ('float', '1.5', 1.5),
+        ('complex', '1+5j', 1 + 5j),
+    ),
+)
+def test_optparse_normalize_types(optmanager, type_s, input_val, expected):
+    """Test the optparse shim for type="typename"."""
+    optmanager.add_option('--foo', type=type_s)
+    opts, args = optmanager.parse_args(['--foo', input_val])
+    assert opts.foo == expected
+
+
+def test_optparse_normalize_choice_type(optmanager):
+    """Test the optparse shim for type="choice"."""
+    optmanager.add_option('--foo', type='choice', choices=('1', '2', '3'))
+    opts, args = optmanager.parse_args(['--foo', '1'])
+    assert opts.foo == '1'
+    # fails to parse
+    with pytest.raises(SystemExit):
+        optmanager.parse_args(['--foo', '4'])
+
+
+def test_optparse_normalize_help(optmanager, capsys):
+    """Test the optparse shim for %default in help text."""
+    optmanager.add_option('--foo', default='bar', help='default: %default')
+    with pytest.raises(SystemExit):
+        optmanager.parse_args(['--help'])
+    out, err = capsys.readouterr()
+    output = out + err
+    assert 'default: bar' in output
diff --git a/tests/unit/test_plugin.py b/tests/unit/test_plugin.py
index 4d5510f..cf87ea1 100644
--- a/tests/unit/test_plugin.py
+++ b/tests/unit/test_plugin.py
@@ -1,5 +1,5 @@
 """Tests for flake8.plugins.manager.Plugin."""
-import optparse
+import argparse
 
 import mock
 import pytest
@@ -124,7 +124,7 @@ def test_provide_options():
     entry_point = mock.Mock(spec=['load'])
     plugin_obj = mock.Mock(spec_set=['name', 'version', 'add_options',
                                      'parse_options'])
-    option_values = optparse.Values({'enable_extensions': []})
+    option_values = argparse.Namespace(enable_extensions=[])
     option_manager = mock.Mock()
     plugin = manager.Plugin('T000', entry_point)
     plugin._plugin = plugin_obj
diff --git a/tests/unit/test_style_guide.py b/tests/unit/test_style_guide.py
index 46ab28e..38121c1 100644
--- a/tests/unit/test_style_guide.py
+++ b/tests/unit/test_style_guide.py
@@ -1,5 +1,5 @@
 """Tests for the flake8.style_guide.StyleGuide class."""
-import optparse
+import argparse
 
 import mock
 import pytest
@@ -11,7 +11,7 @@ from flake8.formatting import base
 
 
 def create_options(**kwargs):
-    """Create and return an instance of optparse.Values."""
+    """Create and return an instance of argparse.Namespace."""
     kwargs.setdefault('select', [])
     kwargs.setdefault('extended_default_select', [])
     kwargs.setdefault('ignore', [])
@@ -19,7 +19,7 @@ def create_options(**kwargs):
     kwargs.setdefault('disable_noqa', False)
     kwargs.setdefault('enable_extensions', [])
     kwargs.setdefault('per_file_ignores', [])
-    return optparse.Values(kwargs)
+    return argparse.Namespace(**kwargs)
 
 
 def test_handle_error_does_not_raise_type_errors():
diff --git a/tox.ini b/tox.ini
index 6765fd8..b7d4fc0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,9 +8,9 @@ deps =
     pytest!=3.0.5
     coverage
 commands =
-    coverage run --parallel-mode -m pytest {posargs}
+    coverage run -m pytest {posargs}
     coverage combine
-    coverage report -m
+    coverage report
 
 [testenv:venv]
 deps =