test_argparse.py

# Author: Steven J. Bethard <steven.bethard@gmail.com>.

import inspect
import os
import shutil
import stat
import sys
import textwrap
import tempfile
import unittest
import argparse

from io import StringIO

from test import support
from test.support import os_helper
from unittest import mock
class StdIOBuffer(StringIO):
    pass

class TestCase(unittest.TestCase):

    def setUp(self):
        # The tests assume that line wrapping occurs at 80 columns, but this
        # behaviour can be overridden by setting the COLUMNS environment
        # variable.  To ensure that this width is used, set COLUMNS to 80.
        env = os_helper.EnvironmentVarGuard()
        env['COLUMNS'] = '80'
        self.addCleanup(env.__exit__)


class TempDirMixin(object):

    def setUp(self):
        self.temp_dir = tempfile.mkdtemp()
        self.old_dir = os.getcwd()
        os.chdir(self.temp_dir)

    def tearDown(self):
        os.chdir(self.old_dir)
        for root, dirs, files in os.walk(self.temp_dir, topdown=False):
            for name in files:
                os.chmod(os.path.join(self.temp_dir, name), stat.S_IWRITE)
        shutil.rmtree(self.temp_dir, True)

    def create_readonly_file(self, filename):
        file_path = os.path.join(self.temp_dir, filename)
        with open(file_path, 'w') as file:
            file.write(filename)
        os.chmod(file_path, stat.S_IREAD)

class Sig(object):

    def __init__(self, *args, **kwargs):
        self.args = args
        self.kwargs = kwargs


class NS(object):

    def __init__(self, **kwargs):
        self.__dict__.update(kwargs)

    def __repr__(self):
        sorted_items = sorted(self.__dict__.items())
        kwarg_str = ', '.join(['%s=%r' % tup for tup in sorted_items])
        return '%s(%s)' % (type(self).__name__, kwarg_str)

    def __eq__(self, other):
        return vars(self) == vars(other)


class ArgumentParserError(Exception):

    def __init__(self, message, stdout=None, stderr=None, error_code=None):
        Exception.__init__(self, message, stdout, stderr)
        self.message = message
        self.stdout = stdout
        self.stderr = stderr
        self.error_code = error_code


def stderr_to_parser_error(parse_args, *args, **kwargs):
    # if this is being called recursively and stderr or stdout is already being
    # redirected, simply call the function and let the enclosing function
    # catch the exception
    if isinstance(sys.stderr, StdIOBuffer) or isinstance(sys.stdout, StdIOBuffer):
        return parse_args(*args, **kwargs)

    # if this is not being called recursively, redirect stderr and
    # use it as the ArgumentParserError message
    old_stdout = sys.stdout
    old_stderr = sys.stderr
    sys.stdout = StdIOBuffer()
    sys.stderr = StdIOBuffer()
    try:
        try:
            result = parse_args(*args, **kwargs)
            for key in list(vars(result)):
                if getattr(result, key) is sys.stdout:
                    setattr(result, key, old_stdout)
                if getattr(result, key) is sys.stderr:
                    setattr(result, key, old_stderr)
            return result
        except SystemExit:
            code = sys.exc_info()[1].code
            stdout = sys.stdout.getvalue()
            stderr = sys.stderr.getvalue()
            raise ArgumentParserError(
                "SystemExit", stdout, stderr, code) from None
    finally:
        sys.stdout = old_stdout
        sys.stderr = old_stderr


class ErrorRaisingArgumentParser(argparse.ArgumentParser):

    def parse_args(self, *args, **kwargs):
        parse_args = super(ErrorRaisingArgumentParser, self).parse_args
        return stderr_to_parser_error(parse_args, *args, **kwargs)

    def exit(self, *args, **kwargs):
        exit = super(ErrorRaisingArgumentParser, self).exit
        return stderr_to_parser_error(exit, *args, **kwargs)

    def error(self, *args, **kwargs):
        error = super(ErrorRaisingArgumentParser, self).error
        return stderr_to_parser_error(error, *args, **kwargs)


class ParserTesterMetaclass(type):
    """Adds parser tests using the class attributes.

    Classes of this type should specify the following attributes:

    argument_signatures -- a list of Sig objects which specify
        the signatures of Argument objects to be created
    failures -- a list of args lists that should cause the parser
        to fail
    successes -- a list of (initial_args, options, remaining_args) tuples
        where initial_args specifies the string args to be parsed,
        options is a dict that should match the vars() of the options
        parsed out of initial_args, and remaining_args should be any
        remaining unparsed arguments
    """

    def __init__(cls, name, bases, bodydict):
        if name == 'ParserTestCase':
            return

        # default parser signature is empty
        if not hasattr(cls, 'parser_signature'):
            cls.parser_signature = Sig()
        if not hasattr(cls, 'parser_class'):
            cls.parser_class = ErrorRaisingArgumentParser

        # ---------------------------------------
        # functions for adding optional arguments
        # ---------------------------------------
        def no_groups(parser, argument_signatures):
            """Add all arguments directly to the parser"""
            for sig in argument_signatures:
                parser.add_argument(*sig.args, **sig.kwargs)

        def one_group(parser, argument_signatures):
            """Add all arguments under a single group in the parser"""
            group = parser.add_argument_group('foo')
            for sig in argument_signatures:
                group.add_argument(*sig.args, **sig.kwargs)

        def many_groups(parser, argument_signatures):
            """Add each argument in its own group to the parser"""
            for i, sig in enumerate(argument_signatures):
                group = parser.add_argument_group('foo:%i' % i)
                group.add_argument(*sig.args, **sig.kwargs)

        # --------------------------
        # functions for parsing args
        # --------------------------
        def listargs(parser, args):
            """Parse the args by passing in a list"""
            return parser.parse_args(args)

        def sysargs(parser, args):
            """Parse the args by defaulting to sys.argv"""
            old_sys_argv = sys.argv
            sys.argv = [old_sys_argv[0]] + args
            try:
                return parser.parse_args()
            finally:
                sys.argv = old_sys_argv

        # class that holds the combination of one optional argument
        # addition method and one arg parsing method
        class AddTests(object):

            def __init__(self, tester_cls, add_arguments, parse_args):
                self._add_arguments = add_arguments
                self._parse_args = parse_args

                add_arguments_name = self._add_arguments.__name__
                parse_args_name = self._parse_args.__name__
                for test_func in [self.test_failures, self.test_successes]:
                    func_name = test_func.__name__
                    names = func_name, add_arguments_name, parse_args_name
                    test_name = '_'.join(names)

                    def wrapper(self, test_func=test_func):
                        test_func(self)
                    try:
                        wrapper.__name__ = test_name
                    except TypeError:
                        pass
                    setattr(tester_cls, test_name, wrapper)

            def _get_parser(self, tester):
                args = tester.parser_signature.args
                kwargs = tester.parser_signature.kwargs
                parser = tester.parser_class(*args, **kwargs)
                self._add_arguments(parser, tester.argument_signatures)
                return parser

            def test_failures(self, tester):
                parser = self._get_parser(tester)
                for args_str in tester.failures:
                    args = args_str.split()
                    with tester.assertRaises(ArgumentParserError, msg=args):
                        parser.parse_args(args)

            def test_successes(self, tester):
                parser = self._get_parser(tester)
                for args, expected_ns in tester.successes:
                    if isinstance(args, str):
                        args = args.split()
                    result_ns = self._parse_args(parser, args)
                    tester.assertEqual(expected_ns, result_ns)

        # add tests for each combination of an optionals adding method
        # and an arg parsing method
        for add_arguments in [no_groups, one_group, many_groups]:
            for parse_args in [listargs, sysargs]:
                AddTests(cls, add_arguments, parse_args)

bases = TestCase,
ParserTestCase = ParserTesterMetaclass('ParserTestCase', bases, {})

# ===============
# Optionals tests
# ===============

class TestOptionalsSingleDash(ParserTestCase):
    """Test an Optional with a single-dash option string"""

    argument_signatures = [Sig('-x')]
    failures = ['-x', 'a', '--foo', '-x --foo', '-x -y']
    successes = [
        ('', NS(x=None)),
        ('-x a', NS(x='a')),
        ('-xa', NS(x='a')),
        ('-x -1', NS(x='-1')),
        ('-x-1', NS(x='-1')),
    ]


class TestOptionalsSingleDashCombined(ParserTestCase):
    """Test an Optional with a single-dash option string"""

    argument_signatures = [
        Sig('-x', action='store_true'),
        Sig('-yyy', action='store_const', const=42),
        Sig('-z'),
    ]
    failures = ['a', '--foo', '-xa', '-x --foo', '-x -z', '-z -x',
                '-yx', '-yz a', '-yyyx', '-yyyza', '-xyza']
    successes = [
        ('', NS(x=False, yyy=None, z=None)),
        ('-x', NS(x=True, yyy=None, z=None)),
        ('-za', NS(x=False, yyy=None, z='a')),
        ('-z a', NS(x=False, yyy=None, z='a')),
        ('-xza', NS(x=True, yyy=None, z='a')),
        ('-xz a', NS(x=True, yyy=None, z='a')),
        ('-x -za', NS(x=True, yyy=None, z='a')),
        ('-x -z a', NS(x=True, yyy=None, z='a')),
        ('-y', NS(x=False, yyy=42, z=None)),
        ('-yyy', NS(x=False, yyy=42, z=None)),
        ('-x -yyy -za', NS(x=True, yyy=42, z='a')),
        ('-x -yyy -z a', NS(x=True, yyy=42, z='a')),
    ]


class TestOptionalsSingleDashLong(ParserTestCase):
    """Test an Optional with a multi-character single-dash option string"""

    argument_signatures = [Sig('-foo')]
    failures = ['-foo', 'a', '--foo', '-foo --foo', '-foo -y', '-fooa']
    successes = [
        ('', NS(foo=None)),
        ('-foo a', NS(foo='a')),
        ('-foo -1', NS(foo='-1')),
        ('-fo a', NS(foo='a')),
        ('-f a', NS(foo='a')),
    ]


class TestOptionalsSingleDashSubsetAmbiguous(ParserTestCase):
    """Test Optionals where option strings are subsets of each other"""

    argument_signatures = [Sig('-f'), Sig('-foobar'), Sig('-foorab')]
    failures = ['-f', '-foo', '-fo', '-foo b', '-foob', '-fooba', '-foora']
    successes = [
        ('', NS(f=None, foobar=None, foorab=None)),
        ('-f a', NS(f='a', foobar=None, foorab=None)),
        ('-fa', NS(f='a', foobar=None, foorab=None)),
        ('-foa', NS(f='oa', foobar=None, foorab=None)),
        ('-fooa', NS(f='ooa', foobar=None, foorab=None)),
        ('-foobar a', NS(f=None, foobar='a', foorab=None)),
        ('-foorab a', NS(f=None, foobar=None, foorab='a')),
    ]


class TestOptionalsSingleDashAmbiguous(ParserTestCase):
    """Test Optionals that partially match but are not subsets"""

    argument_signatures = [Sig('-foobar'), Sig('-foorab')]
    failures = ['-f', '-f a', '-fa', '-foa', '-foo', '-fo', '-foo b']
    successes = [
        ('', NS(foobar=None, foorab=None)),
        ('-foob a', NS(foobar='a', foorab=None)),
        ('-foor a', NS(foobar=None, foorab='a')),
        ('-fooba a', NS(foobar='a', foorab=None)),
        ('-foora a', NS(foobar=None, foorab='a')),
        ('-foobar a', NS(foobar='a', foorab=None)),
        ('-foorab a', NS(foobar=None, foorab='a')),
    ]


class TestOptionalsNumeric(ParserTestCase):
    """Test an Optional with a short opt string"""

    argument_signatures = [Sig('-1', dest='one')]
    failures = ['-1', 'a', '-1 --foo', '-1 -y', '-1 -1', '-1 -2']
    successes = [
        ('', NS(one=None)),
        ('-1 a', NS(one='a')),
        ('-1a', NS(one='a')),
        ('-1-2', NS(one='-2')),
    ]


class TestOptionalsDoubleDash(ParserTestCase):
    """Test an Optional with a double-dash option string"""

    argument_signatures = [Sig('--foo')]
    failures = ['--foo', '-f', '-f a', 'a', '--foo -x', '--foo --bar']
    successes = [
        ('', NS(foo=None)),
        ('--foo a', NS(foo='a')),
        ('--foo=a', NS(foo='a')),
        ('--foo -2.5', NS(foo='-2.5')),
        ('--foo=-2.5', NS(foo='-2.5')),
    ]


class TestOptionalsDoubleDashPartialMatch(ParserTestCase):
    """Tests partial matching with a double-dash option string"""

    argument_signatures = [
        Sig('--badger', action='store_true'),
        Sig('--bat'),
    ]
    failures = ['--bar', '--b', '--ba', '--b=2', '--ba=4', '--badge 5']
    successes = [
        ('', NS(badger=False, bat=None)),
        ('--bat X', NS(badger=False, bat='X')),
        ('--bad', NS(badger=True, bat=None)),
        ('--badg', NS(badger=True, bat=None)),
        ('--badge', NS(badger=True, bat=None)),
        ('--badger', NS(badger=True, bat=None)),
    ]


class TestOptionalsDoubleDashPrefixMatch(ParserTestCase):
    """Tests when one double-dash option string is a prefix of another"""

    argument_signatures = [
        Sig('--badger', action='store_true'),
        Sig('--ba'),
    ]
    failures = ['--bar', '--b', '--ba', '--b=2', '--badge 5']
    successes = [
        ('', NS(badger=False, ba=None)),
        ('--ba X', NS(badger=False, ba='X')),
        ('--ba=X', NS(badger=False, ba='X')),
        ('--bad', NS(badger=True, ba=None)),
        ('--badg', NS(badger=True, ba=None)),
        ('--badge', NS(badger=True, ba=None)),
        ('--badger', NS(badger=True, ba=None)),
    ]


class TestOptionalsSingleDoubleDash(ParserTestCase):
    """Test an Optional with single- and double-dash option strings"""

    argument_signatures = [
        Sig('-f', action='store_true'),
        Sig('--bar'),
        Sig('-baz', action='store_const', const=42),
    ]
    failures = ['--bar', '-fbar', '-fbaz', '-bazf', '-b B', 'B']
    successes = [
        ('', NS(f=False, bar=None, baz=None)),
        ('-f', NS(f=True, bar=None, baz=None)),
        ('--ba B', NS(f=False, bar='B', baz=None)),
        ('-f --bar B', NS(f=True, bar='B', baz=None)),
        ('-f -b', NS(f=True, bar=None, baz=42)),
        ('-ba -f', NS(f=True, bar=None, baz=42)),
    ]


class TestOptionalsAlternatePrefixChars(ParserTestCase):
    """Test an Optional with option strings with custom prefixes"""

    parser_signature = Sig(prefix_chars='+:/', add_help=False)
    argument_signatures = [
        Sig('+f', action='store_true'),
        Sig('::bar'),
        Sig('/baz', action='store_const', const=42),
    ]
    failures = ['--bar', '-fbar', '-b B', 'B', '-f', '--bar B', '-baz', '-h', '--help', '+h', '::help', '/help']
    successes = [
        ('', NS(f=False, bar=None, baz=None)),
        ('+f', NS(f=True, bar=None, baz=None)),
        ('::ba B', NS(f=False, bar='B', baz=None)),
        ('+f ::bar B', NS(f=True, bar='B', baz=None)),
        ('+f /b', NS(f=True, bar=None, baz=42)),
        ('/ba +f', NS(f=True, bar=None, baz=42)),
    ]


class TestOptionalsAlternatePrefixCharsAddedHelp(ParserTestCase):
    """When ``-`` not in prefix_chars, default operators created for help
       should use the prefix_chars in use rather than - or --
       http://bugs.python.org/issue9444"""

    parser_signature = Sig(prefix_chars='+:/', add_help=True)
    argument_signatures = [
        Sig('+f', action='store_true'),
        Sig('::bar'),
        Sig('/baz', action='store_const', const=42),
    ]
    failures = ['--bar', '-fbar', '-b B', 'B', '-f', '--bar B', '-baz']
    successes = [
        ('', NS(f=False, bar=None, baz=None)),
        ('+f', NS(f=True, bar=None, baz=None)),
        ('::ba B', NS(f=False, bar='B', baz=None)),
        ('+f ::bar B', NS(f=True, bar='B', baz=None)),
        ('+f /b', NS(f=True, bar=None, baz=42)),
        ('/ba +f', NS(f=True, bar=None, baz=42))
    ]


class TestOptionalsAlternatePrefixCharsMultipleShortArgs(ParserTestCase):
    """Verify that Optionals must be called with their defined prefixes"""

    parser_signature = Sig(prefix_chars='+-', add_help=False)
    argument_signatures = [
        Sig('-x', action='store_true'),
        Sig('+y', action='store_true'),
        Sig('+z', action='store_true'),
    ]
    failures = ['-w',
                '-xyz',
                '+x',
                '-y',
                '+xyz',
    ]
    successes = [
        ('', NS(x=False, y=False, z=False)),
        ('-x', NS(x=True, y=False, z=False)),
        ('+y -x', NS(x=True, y=True, z=False)),
        ('+yz -x', NS(x=True, y=True, z=True)),
    ]


class TestOptionalsShortLong(ParserTestCase):
    """Test a combination of single- and double-dash option strings"""

    argument_signatures = [
        Sig('-v', '--verbose', '-n', '--noisy', action='store_true'),
    ]
    failures = ['--x --verbose', '-N', 'a', '-v x']
    successes = [
        ('', NS(verbose=False)),
        ('-v', NS(verbose=True)),
        ('--verbose', NS(verbose=True)),
        ('-n', NS(verbose=True)),
        ('--noisy', NS(verbose=True)),
    ]


class TestOptionalsDest(ParserTestCase):
    """Tests various means of setting destination"""

    argument_signatures = [Sig('--foo-bar'), Sig('--baz', dest='zabbaz')]
    failures = ['a']
    successes = [
        ('--foo-bar f', NS(foo_bar='f', zabbaz=None)),
        ('--baz g', NS(foo_bar=None, zabbaz='g')),
        ('--foo-bar h --baz i', NS(foo_bar='h', zabbaz='i')),
        ('--baz j --foo-bar k', NS(foo_bar='k', zabbaz='j')),
    ]


class TestOptionalsDefault(ParserTestCase):
    """Tests specifying a default for an Optional"""

    argument_signatures = [Sig('-x'), Sig('-y', default=42)]
    failures = ['a']
    successes = [
        ('', NS(x=None, y=42)),
        ('-xx', NS(x='x', y=42)),
        ('-yy', NS(x=None, y='y')),
    ]


class TestOptionalsNargsDefault(ParserTestCase):
    """Tests not specifying the number of args for an Optional"""

    argument_signatures = [Sig('-x')]
    failures = ['a', '-x']
    successes = [
        ('', NS(x=None)),
        ('-x a', NS(x='a')),
    ]


class TestOptionalsNargs1(ParserTestCase):
    """Tests specifying 1 arg for an Optional"""

    argument_signatures = [Sig('-x', nargs=1)]
    failures = ['a', '-x']
    successes = [
        ('', NS(x=None)),
        ('-x a', NS(x=['a'])),
    ]


class TestOptionalsNargs3(ParserTestCase):
    """Tests specifying 3 args for an Optional"""

    argument_signatures = [Sig('-x', nargs=3)]
    failures = ['a', '-x', '-x a', '-x a b', 'a -x', 'a -x b']
    successes = [
        ('', NS(x=None)),
        ('-x a b c', NS(x=['a', 'b', 'c'])),
    ]


class TestOptionalsNargsOptional(ParserTestCase):
    """Tests specifying an Optional arg for an Optional"""

    argument_signatures = [
        Sig('-w', nargs='?'),
        Sig('-x', nargs='?', const=42),
        Sig('-y', nargs='?', default='spam'),
        Sig('-z', nargs='?', type=int, const='42', default='84'),
    ]
    failures = ['2']
    successes = [
        ('', NS(w=None, x=None, y='spam', z=84)),
        ('-w', NS(w=None, x=None, y='spam', z=84)),
        ('-w 2', NS(w='2', x=None, y='spam', z=84)),
        ('-x', NS(w=None, x=42, y='spam', z=84)),
        ('-x 2', NS(w=None, x='2', y='spam', z=84)),
        ('-y', NS(w=None, x=None, y=None, z=84)),
        ('-y 2', NS(w=None, x=None, y='2', z=84)),
        ('-z', NS(w=None, x=None, y='spam', z=42)),
        ('-z 2', NS(w=None, x=None, y='spam', z=2)),
    ]


class TestOptionalsNargsZeroOrMore(ParserTestCase):
    """Tests specifying args for an Optional that accepts zero or more"""

    argument_signatures = [
        Sig('-x', nargs='*'),
        Sig('-y', nargs='*', default='spam'),
    ]
    failures = ['a']
    successes = [
        ('', NS(x=None, y='spam')),
        ('-x', NS(x=[], y='spam')),
        ('-x a', NS(x=['a'], y='spam')),
        ('-x a b', NS(x=['a', 'b'], y='spam')),
        ('-y', NS(x=None, y=[])),
        ('-y a', NS(x=None, y=['a'])),
        ('-y a b', NS(x=None, y=['a', 'b'])),
    ]


class TestOptionalsNargsOneOrMore(ParserTestCase):
    """Tests specifying args for an Optional that accepts one or more"""

    argument_signatures = [
        Sig('-x', nargs='+'),
        Sig('-y', nargs='+', default='spam'),
    ]
    failures = ['a', '-x', '-y', 'a -x', 'a -y b']
    successes = [
        ('', NS(x=None, y='spam')),
        ('-x a', NS(x=['a'], y='spam')),
        ('-x a b', NS(x=['a', 'b'], y='spam')),
        ('-y a', NS(x=None, y=['a'])),
        ('-y a b', NS(x=None, y=['a', 'b'])),
    ]


class TestOptionalsChoices(ParserTestCase):
    """Tests specifying the choices for an Optional"""

    argument_signatures = [
        Sig('-f', choices='abc'),
        Sig('-g', type=int, choices=range(5))]
    failures = ['a', '-f d', '-fad', '-ga', '-g 6']
    successes = [
        ('', NS(f=None, g=None)),
        ('-f a', NS(f='a', g=None)),
        ('-f c', NS(f='c', g=None)),
        ('-g 0', NS(f=None, g=0)),
        ('-g 03', NS(f=None, g=3)),
        ('-fb -g4', NS(f='b', g=4)),
    ]


class TestOptionalsRequired(ParserTestCase):
    """Tests an optional action that is required"""

    argument_signatures = [
        Sig('-x', type=int, required=True),
    ]
    failures = ['a', '']
    successes = [
        ('-x 1', NS(x=1)),
        ('-x42', NS(x=42)),
    ]


class TestOptionalsActionStore(ParserTestCase):
    """Tests the store action for an Optional"""

    argument_signatures = [Sig('-x', action='store')]
    failures = ['a', 'a -x']
    successes = [
        ('', NS(x=None)),
        ('-xfoo', NS(x='foo')),
    ]


class TestOptionalsActionStoreConst(ParserTestCase):
    """Tests the store_const action for an Optional"""

    argument_signatures = [Sig('-y', action='store_const', const=object)]
    failures = ['a']
    successes = [
        ('', NS(y=None)),
        ('-y', NS(y=object)),
    ]


class TestOptionalsActionStoreFalse(ParserTestCase):
    """Tests the store_false action for an Optional"""

    argument_signatures = [Sig('-z', action='store_false')]
    failures = ['a', '-za', '-z a']
    successes = [
        ('', NS(z=True)),
        ('-z', NS(z=False)),
    ]


class TestOptionalsActionStoreTrue(ParserTestCase):
    """Tests the store_true action for an Optional"""

    argument_signatures = [Sig('--apple', action='store_true')]
    failures = ['a', '--apple=b', '--apple b']
    successes = [
        ('', NS(apple=False)),
        ('--apple', NS(apple=True)),
    ]

class TestBooleanOptionalAction(ParserTestCase):
    """Tests BooleanOptionalAction"""

    argument_signatures = [Sig('--foo', action=argparse.BooleanOptionalAction)]
    failures = ['--foo bar', '--foo=bar']
    successes = [
        ('', NS(foo=None)),
        ('--foo', NS(foo=True)),
        ('--no-foo', NS(foo=False)),
        ('--foo --no-foo', NS(foo=False)),  # useful for aliases
        ('--no-foo --foo', NS(foo=True)),
    ]

    def test_const(self):
        # See bpo-40862
        parser = argparse.ArgumentParser()
        with self.assertRaises(TypeError) as cm:
            parser.add_argument('--foo', const=True, action=argparse.BooleanOptionalAction)

        self.assertIn("got an unexpected keyword argument 'const'", str(cm.exception))

class TestBooleanOptionalActionRequired(ParserTestCase):
    """Tests BooleanOptionalAction required"""

    argument_signatures = [
        Sig('--foo', required=True, action=argparse.BooleanOptionalAction)
    ]
    failures = ['']
    successes = [
        ('--foo', NS(foo=True)),
        ('--no-foo', NS(foo=False)),
    ]

class TestOptionalsActionAppend(ParserTestCase):
    """Tests the append action for an Optional"""

    argument_signatures = [Sig('--baz', action='append')]
    failures = ['a', '--baz', 'a --baz', '--baz a b']
    successes = [
        ('', NS(baz=None)),
        ('--baz a', NS(baz=['a'])),
        ('--baz a --baz b', NS(baz=['a', 'b'])),
    ]


class TestOptionalsActionAppendWithDefault(ParserTestCase):
    """Tests the append action for an Optional"""

    argument_signatures = [Sig('--baz', action='append', default=['X'])]
    failures = ['a', '--baz', 'a --baz', '--baz a b']
    successes = [
        ('', NS(baz=['X'])),
        ('--baz a', NS(baz=['X', 'a'])),
        ('--baz a --baz b', NS(baz=['X', 'a', 'b'])),
    ]


class TestOptionalsActionAppendConst(ParserTestCase):
    """Tests the append_const action for an Optional"""

    argument_signatures = [
        Sig('-b', action='append_const', const=Exception),
        Sig('-c', action='append', dest='b'),
    ]
    failures = ['a', '-c', 'a -c', '-bx', '-b x']
    successes = [
        ('', NS(b=None)),
        ('-b', NS(b=[Exception])),
        ('-b -cx -b -cyz', NS(b=[Exception, 'x', Exception, 'yz'])),
    ]


class TestOptionalsActionAppendConstWithDefault(ParserTestCase):
    """Tests the append_const action for an Optional"""

    argument_signatures = [
        Sig('-b', action='append_const', const=Exception, default=['X']),
        Sig('-c', action='append', dest='b'),
    ]
    failures = ['a', '-c', 'a -c', '-bx', '-b x']
    successes = [
        ('', NS(b=['X'])),
        ('-b', NS(b=['X', Exception])),
        ('-b -cx -b -cyz', NS(b=['X', Exception, 'x', Exception, 'yz'])),
    ]


class TestOptionalsActionCount(ParserTestCase):
    """Tests the count action for an Optional"""

    argument_signatures = [Sig('-x', action='count')]
    failures = ['a', '-x a', '-x b', '-x a -x b']
    successes = [
        ('', NS(x=None)),
        ('-x', NS(x=1)),
    ]


class TestOptionalsAllowLongAbbreviation(ParserTestCase):
    """Allow long options to be abbreviated unambiguously"""

    argument_signatures = [
        Sig('--foo'),
        Sig('--foobaz'),
        Sig('--fooble', action='store_true'),
    ]
    failures = ['--foob 5', '--foob']
    successes = [
        ('', NS(foo=None, foobaz=None, fooble=False)),
        ('--foo 7', NS(foo='7', foobaz=None, fooble=False)),
        ('--fooba a', NS(foo=None, foobaz='a', fooble=False)),
        ('--foobl --foo g', NS(foo='g', foobaz=None, fooble=True)),
    ]


class TestOptionalsDisallowLongAbbreviation(ParserTestCase):
    """Do not allow abbreviations of long options at all"""

    parser_signature = Sig(allow_abbrev=False)
    argument_signatures = [
        Sig('--foo'),
        Sig('--foodle', action='store_true'),
        Sig('--foonly'),
    ]
    failures = ['-foon 3', '--foon 3', '--food', '--food --foo 2']
    successes = [
        ('', NS(foo=None, foodle=False, foonly=None)),
        ('--foo 3', NS(foo='3', foodle=False, foonly=None)),
        ('--foonly 7 --foodle --foo 2', NS(foo='2', foodle=True, foonly='7')),
    ]


class TestOptionalsDisallowLongAbbreviationPrefixChars(ParserTestCase):
    """Disallowing abbreviations works with alternative prefix characters"""

    parser_signature = Sig(prefix_chars='+', allow_abbrev=False)
    argument_signatures = [
        Sig('++foo'),
        Sig('++foodle', action='store_true'),
        Sig('++foonly'),
    ]
    failures = ['+foon 3', '++foon 3', '++food', '++food ++foo 2']
    successes = [
        ('', NS(foo=None, foodle=False, foonly=None)),
        ('++foo 3', NS(foo='3', foodle=False, foonly=None)),
        ('++foonly 7 ++foodle ++foo 2', NS(foo='2', foodle=True, foonly='7')),
    ]


class TestDisallowLongAbbreviationAllowsShortGrouping(ParserTestCase):
    """Do not allow abbreviations of long options at all"""

    parser_signature = Sig(allow_abbrev=False)
    argument_signatures = [
        Sig('-r'),
        Sig('-c', action='count'),
    ]
    failures = ['-r', '-c -r']
    successes = [
        ('', NS(r=None, c=None)),
        ('-ra', NS(r='a', c=None)),
        ('-rcc', NS(r='cc', c=None)),
        ('-cc', NS(r=None, c=2)),
        ('-cc -ra', NS(r='a', c=2)),
        ('-ccrcc', NS(r='cc', c=2)),
    ]


class TestDisallowLongAbbreviationAllowsShortGroupingPrefix(ParserTestCase):
    """Short option grouping works with custom prefix and allow_abbrev=False"""

    parser_signature = Sig(prefix_chars='+', allow_abbrev=False)
    argument_signatures = [
        Sig('+r'),
        Sig('+c', action='count'),
    ]
    failures = ['+r', '+c +r']
    successes = [
        ('', NS(r=None, c=None)),
        ('+ra', NS(r='a', c=None)),
        ('+rcc', NS(r='cc', c=None)),
        ('+cc', NS(r=None, c=2)),
        ('+cc +ra', NS(r='a', c=2)),
        ('+ccrcc', NS(r='cc', c=2)),
    ]


# ================
# Positional tests
# ================

class TestPositionalsNargsNone(ParserTestCase):
    """Test a Positional that doesn't specify nargs"""

    argument_signatures = [Sig('foo')]
    failures = ['', '-x', 'a b']
    successes = [
        ('a', NS(foo='a')),
    ]


class TestPositionalsNargs1(ParserTestCase):
    """Test a Positional that specifies an nargs of 1"""

    argument_signatures = [Sig('foo', nargs=1)]
    failures = ['', '-x', 'a b']
    successes = [
        ('a', NS(foo=['a'])),
    ]


class TestPositionalsNargs2(ParserTestCase):
    """Test a Positional that specifies an nargs of 2"""

    argument_signatures = [Sig('foo', nargs=2)]
    failures = ['', 'a', '-x', 'a b c']
    successes = [
        ('a b', NS(foo=['a', 'b'])),
    ]


class TestPositionalsNargsZeroOrMore(ParserTestCase):
    """Test a Positional that specifies unlimited nargs"""

    argument_signatures = [Sig('foo', nargs='*')]
    failures = ['-x']
    successes = [
        ('', NS(foo=[])),
        ('a', NS(foo=['a'])),
        ('a b', NS(foo=['a', 'b'])),
    ]


class TestPositionalsNargsZeroOrMoreDefault(ParserTestCase):
    """Test a Positional that specifies unlimited nargs and a default"""

    argument_signatures = [Sig('foo', nargs='*', default='bar')]
    failures = ['-x']
    successes = [
        ('', NS(foo='bar')),
        ('a', NS(foo=['a'])),
        ('a b', NS(foo=['a', 'b'])),
    ]


class TestPositionalsNargsOneOrMore(ParserTestCase):
    """Test a Positional that specifies one or more nargs"""

    argument_signatures = [Sig('foo', nargs='+')]
    failures = ['', '-x']
    successes = [
        ('a', NS(foo=['a'])),
        ('a b', NS(foo=['a', 'b'])),
    ]


class TestPositionalsNargsOptional(ParserTestCase):
    """Tests an Optional Positional"""

    argument_signatures = [Sig('foo', nargs='?')]
    failures = ['-x', 'a b']
    successes = [
        ('', NS(foo=None)),
        ('a', NS(foo='a')),
    ]


class TestPositionalsNargsOptionalDefault(ParserTestCase):
    """Tests an Optional Positional with a default value"""

    argument_signatures = [Sig('foo', nargs='?', default=42)]
    failures = ['-x', 'a b']
    successes = [
        ('', NS(foo=42)),
        ('a', NS(foo='a')),
    ]


class TestPositionalsNargsOptionalConvertedDefault(ParserTestCase):
    """Tests an Optional Positional with a default value
    that needs to be converted to the appropriate type.
    """

    argument_signatures = [
        Sig('foo', nargs='?', type=int, default='42'),
    ]
    failures = ['-x', 'a b', '1 2']
    successes = [
        ('', NS(foo=42)),
        ('1', NS(foo=1)),
    ]


class TestPositionalsNargsNoneNone(ParserTestCase):
    """Test two Positionals that don't specify nargs"""

    argument_signatures = [Sig('foo'), Sig('bar')]
    failures = ['', '-x', 'a', 'a b c']
    successes = [
        ('a b', NS(foo='a', bar='b')),
    ]


class TestPositionalsNargsNone1(ParserTestCase):
    """Test a Positional with no nargs followed by one with 1"""

    argument_signatures = [Sig('foo'), Sig('bar', nargs=1)]
    failures = ['', '--foo', 'a', 'a b c']
    successes = [
        ('a b', NS(foo='a', bar=['b'])),