add files from python 2.7.1 (Python License)

1 files changed, 4349 insertions, 0 deletions

diff --git a/test/test_argparse.py b/test/test_argparse.py
new file mode 100644
index 0000000..3e71f57
--- /dev/null
+++ b/test/test_argparse.py
@@ -0,0 +1,4349 @@
+# Author: Steven J. Bethard <steven.bethard@gmail.com>.
+
+import codecs
+import inspect
+import os
+import shutil
+import sys
+import textwrap
+import tempfile
+import unittest
+import argparse
+
+from StringIO import StringIO
+
+class StdIOBuffer(StringIO):
+    pass
+
+from test import test_support
+
+class TestCase(unittest.TestCase):
+
+    def assertEqual(self, obj1, obj2):
+        if obj1 != obj2:
+            print('')
+            print(repr(obj1))
+            print(repr(obj2))
+            print(obj1)
+            print(obj2)
+        super(TestCase, self).assertEqual(obj1, obj2)
+
+    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 assumption is true, unset COLUMNS.
+        env = test_support.EnvironmentVarGuard()
+        env.unset("COLUMNS")
+        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)
+        while True:
+            try:
+                shutil.rmtree(self.temp_dir)
+            except WindowsError:
+                continue
+            else:
+                break
+
+
+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)
+
+    __hash__ = None
+
+    def __eq__(self, other):
+        return vars(self) == vars(other)
+
+    def __ne__(self, other):
+        return not (self == 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)
+    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()
+                    raises = tester.assertRaises
+                    raises(ArgumentParserError, 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 the 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 the 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 an 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 an 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 the 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 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)),
+    ]
+
+
+# ================
+# 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'])),
+    ]
+
+
+class TestPositionalsNargs2None(ParserTestCase):
+    """Test a Positional with 2 nargs followed by one with none"""
+
+    argument_signatures = [Sig('foo', nargs=2), Sig('bar')]
+    failures = ['', '--foo', 'a', 'a b', 'a b c d']
+    successes = [
+        ('a b c', NS(foo=['a', 'b'], bar='c')),
+    ]
+
+
+class TestPositionalsNargsNoneZeroOrMore(ParserTestCase):
+    """Test a Positional with no nargs followed by one with unlimited"""
+
+    argument_signatures = [Sig('foo'), Sig('bar', nargs='*')]
+    failures = ['', '--foo']
+    successes = [
+        ('a', NS(foo='a', bar=[])),
+        ('a b', NS(foo='a', bar=['b'])),
+        ('a b c', NS(foo='a', bar=['b', 'c'])),
+    ]
+
+
+class TestPositionalsNargsNoneOneOrMore(ParserTestCase):
+    """Test a Positional with no nargs followed by one with one or more"""
+
+    argument_signatures = [Sig('foo'), Sig('bar', nargs='+')]
+    failures = ['', '--foo', 'a']
+    successes = [
+        ('a b', NS(foo='a', bar=['b'])),
+        ('a b c', NS(foo='a', bar=['b', 'c'])),
+    ]
+
+
+class TestPositionalsNargsNoneOptional(ParserTestCase):
+    """Test a Positional with no nargs followed by one with an Optional"""
+
+    argument_signatures = [Sig('foo'), Sig('bar', nargs='?')]
+    failures = ['', '--foo', 'a b c']
+    successes = [
+        ('a', NS(foo='a', bar=None)),
+        ('a b', NS(foo='a', bar='b')),
+    ]
+
+
+class TestPositionalsNargsZeroOrMoreNone(ParserTestCase):
+    """Test a Positional with unlimited nargs followed by one with none"""
+
+    argument_signatures = [Sig('foo', nargs='*'), Sig('bar')]
+    failures = ['', '--foo']
+    successes = [
+        ('a', NS(foo=[], bar='a')),
+        ('a b', NS(foo=['a'], bar='b')),
+        ('a b c', NS(foo=['a', 'b'], bar='c')),
+    ]
+
+
+class TestPositionalsNargsOneOrMoreNone(ParserTestCase):
+    """Test a Positional with one or more nargs followed by one with none"""
+
+    argument_signatures = [Sig('foo', nargs='+'), Sig('bar')]
+    failures = ['', '--foo', 'a']
+    successes = [
+        ('a b', NS(foo=['a'], bar='b')),
+        ('a b c', NS(foo=['a', 'b'], bar='c')),
+    ]
+
+
+class TestPositionalsNargsOptionalNone(ParserTestCase):
+    """Test a Positional with an Optional nargs followed by one with none"""
+
+    argument_signatures = [Sig('foo', nargs='?', default=42), Sig('bar')]
+    failures = ['', '--foo', 'a b c']
+    successes = [
+        ('a', NS(foo=42, bar='a')),
+        ('a b', NS(foo='a', bar='b')),
+    ]
+
+
+class TestPositionalsNargs2ZeroOrMore(ParserTestCase):
+    """Test a Positional with 2 nargs followed by one with unlimited"""
+
+    argument_signatures = [Sig('foo', nargs=2), Sig('bar', nargs='*')]
+    failures = ['', '--foo', 'a']
+    successes = [
+        ('a b', NS(foo=['a', 'b'], bar=[])),
+        ('a b c', NS(foo=['a', 'b'], bar=['c'])),
+    ]
+
+
+class TestPositionalsNargs2OneOrMore(ParserTestCase):
+    """Test a Positional with 2 nargs followed by one with one or more"""
+
+    argument_signatures = [Sig('foo', nargs=2), Sig('bar', nargs='+')]
+    failures = ['', '--foo', 'a', 'a b']
+    successes = [
+        ('a b c', NS(foo=['a', 'b'], bar=['c'])),
+    ]
+
+
+class TestPositionalsNargs2Optional(ParserTestCase):
+    """Test a Positional with 2 nargs followed by one optional"""
+
+    argument_signatures = [Sig('foo', nargs=2), Sig('bar', nargs='?')]
+    failures = ['', '--foo', 'a', 'a b c d']
+    successes = [
+        ('a b', NS(foo=['a', 'b'], bar=None)),
+        ('a b c', NS(foo=['a', 'b'], bar='c')),
+    ]
+
+
+class TestPositionalsNargsZeroOrMore1(ParserTestCase):
+    """Test a Positional with unlimited nargs followed by one with 1"""
+
+    argument_signatures = [Sig('foo', nargs='*'), Sig('bar', nargs=1)]
+    failures = ['', '--foo', ]
+    successes = [
+        ('a', NS(foo=[], bar=['a'])),
+        ('a b', NS(foo=['a'], bar=['b'])),
+        ('a b c', NS(foo=['a', 'b'], bar=['c'])),
+    ]
+
+
+class TestPositionalsNargsOneOrMore1(ParserTestCase):
+    """Test a Positional with one or more nargs followed by one with 1"""
+
+    argument_signatures = [Sig('foo', nargs='+'), Sig('bar', nargs=1)]
+    failures = ['', '--foo', 'a']
+    successes = [
+        ('a b', NS(foo=['a'], bar=['b'])),
+        ('a b c', NS(foo=['a', 'b'], bar=['c'])),
+    ]
+
+
+class TestPositionalsNargsOptional1(ParserTestCase):
+    """Test a Positional with an Optional nargs followed by one with 1"""
+
+    argument_signatures = [Sig('foo', nargs='?'), Sig('bar', nargs=1)]
+    failures = ['', '--foo', 'a b c']
+    successes = [
+        ('a', NS(foo=None, bar=['a'])),
+        ('a b', NS(foo='a', bar=['b'])),
+    ]
+
+
+class TestPositionalsNargsNoneZeroOrMore1(ParserTestCase):
+    """Test three Positionals: no nargs, unlimited nargs and 1 nargs"""
+
+    argument_signatures = [
+        Sig('foo'),
+        Sig('bar', nargs='*'),
+        Sig('baz', nargs=1),
+    ]
+    failures = ['', '--foo', 'a']
+    successes = [
+        ('a b', NS(foo='a', bar=[], baz=['b'])),
+        ('a b c', NS(foo='a', bar=['b'], baz=['c'])),
+    ]
+
+
+class TestPositionalsNargsNoneOneOrMore1(ParserTestCase):
+    """Test three Positionals: no nargs, one or more nargs and 1 nargs"""
+
+    argument_signatures = [
+        Sig('foo'),
+        Sig('bar', nargs='+'),
+        Sig('baz', nargs=1),
+    ]
+    failures = ['', '--foo', 'a', 'b']
+    successes = [
+        ('a b c', NS(foo='a', bar=['b'], baz=['c'])),
+        ('a b c d', NS(foo='a', bar=['b', 'c'], baz=['d'])),
+    ]
+
+
+class TestPositionalsNargsNoneOptional1(ParserTestCase):
+    """Test three Positionals: no nargs, optional narg and 1 nargs"""
+
+    argument_signatures = [
+        Sig('foo'),
+        Sig('bar', nargs='?', default=0.625),
+        Sig('baz', nargs=1),
+    ]
+    failures = ['', '--foo', 'a']
+    successes = [
+        ('a b', NS(foo='a', bar=0.625, baz=['b'])),
+        ('a b c', NS(foo='a', bar='b', baz=['c'])),
+    ]
+
+
+class TestPositionalsNargsOptionalOptional(ParserTestCase):
+    """Test two optional nargs"""
+
+    argument_signatures = [
+        Sig('foo', nargs='?'),
+        Sig('bar', nargs='?', default=42),
+    ]
+    failures = ['--foo', 'a b c']
+    successes = [
+        ('', NS(foo=None, bar=42)),
+        ('a', NS(foo='a', bar=42)),
+        ('a b', NS(foo='a', bar='b')),
+    ]
+
+
+class TestPositionalsNargsOptionalZeroOrMore(ParserTestCase):
+    """Test an Optional narg followed by unlimited nargs"""
+
+    argument_signatures = [Sig('foo', nargs='?'), Sig('bar', nargs='*')]
+    failures = ['--foo']
+    successes = [
+        ('', NS(foo=None, bar=[])),
+        ('a', NS(foo='a', bar=[])),
+        ('a b', NS(foo='a', bar=['b'])),
+        ('a b c', NS(foo='a', bar=['b', 'c'])),
+    ]
+
+
+class TestPositionalsNargsOptionalOneOrMore(ParserTestCase):
+    """Test an Optional narg followed by one or more nargs"""
+
+    argument_signatures = [Sig('foo', nargs='?'), Sig('bar', nargs='+')]
+    failures = ['', '--foo']
+    successes = [
+        ('a', NS(foo=None, bar=['a'])),
+        ('a b', NS(foo='a', bar=['b'])),
+        ('a b c', NS(foo='a', bar=['b', 'c'])),
+    ]
+
+
+class TestPositionalsChoicesString(ParserTestCase):
+    """Test a set of single-character choices"""
+
+    argument_signatures = [Sig('spam', choices=set('abcdefg'))]
+    failures = ['', '--foo', 'h', '42', 'ef']
+    successes = [
+        ('a', NS(spam='a')),
+        ('g', NS(spam='g')),
+    ]
+
+
+class TestPositionalsChoicesInt(ParserTestCase):
+    """Test a set of integer choices"""
+
+    argument_signatures = [Sig('spam', type=int, choices=range(20))]
+    failures = ['', '--foo', 'h', '42', 'ef']
+    successes = [
+        ('4', NS(spam=4)),
+        ('15', NS(spam=15)),
+    ]
+
+
+class TestPositionalsActionAppend(ParserTestCase):
+    """Test the 'append' action"""
+
+    argument_signatures = [
+        Sig('spam', action='append'),
+        Sig('spam', action='append', nargs=2),
+    ]
+    failures = ['', '--foo', 'a', 'a b', 'a b c d']
+    successes = [
+        ('a b c', NS(spam=['a', ['b', 'c']])),
+    ]
+
+# ========================================
+# Combined optionals and positionals tests
+# ========================================
+
+class TestOptionalsNumericAndPositionals(ParserTestCase):
+    """Tests negative number args when numeric options are present"""
+
+    argument_signatures = [
+        Sig('x', nargs='?'),
+        Sig('-4', dest='y', action='store_true'),
+    ]
+    failures = ['-2', '-315']
+    successes = [
+        ('', NS(x=None, y=False)),
+        ('a', NS(x='a', y=False)),
+        ('-4', NS(x=None, y=True)),
+        ('-4 a', NS(x='a', y=True)),
+    ]
+
+
+class TestOptionalsAlmostNumericAndPositionals(ParserTestCase):
+    """Tests negative number args when almost numeric options are present"""
+
+    argument_signatures = [
+        Sig('x', nargs='?'),
+        Sig('-k4', dest='y', action='store_true'),
+    ]
+    failures = ['-k3']
+    successes = [
+        ('', NS(x=None, y=False)),
+        ('-2', NS(x='-2', y=False)),
+        ('a', NS(x='a', y=False)),
+        ('-k4', NS(x=None, y=True)),
+        ('-k4 a', NS(x='a', y=True)),
+    ]
+
+
+class TestEmptyAndSpaceContainingArguments(ParserTestCase):
+
+    argument_signatures = [
+        Sig('x', nargs='?'),
+        Sig('-y', '--yyy', dest='y'),
+    ]
+    failures = ['-y']
+    successes = [
+        ([''], NS(x='', y=None)),
+        (['a badger'], NS(x='a badger', y=None)),
+        (['-a badger'], NS(x='-a badger', y=None)),
+        (['-y', ''], NS(x=None, y='')),
+        (['-y', 'a badger'], NS(x=None, y='a badger')),
+        (['-y', '-a badger'], NS(x=None, y='-a badger')),
+        (['--yyy=a badger'], NS(x=None, y='a badger')),
+        (['--yyy=-a badger'], NS(x=None, y='-a badger')),
+    ]
+
+
+class TestPrefixCharacterOnlyArguments(ParserTestCase):
+
+    parser_signature = Sig(prefix_chars='-+')
+    argument_signatures = [
+        Sig('-', dest='x', nargs='?', const='badger'),
+        Sig('+', dest='y', type=int, default=42),
+        Sig('-+-', dest='z', action='store_true'),
+    ]
+    failures = ['-y', '+ -']
+    successes = [
+        ('', NS(x=None, y=42, z=False)),
+        ('-', NS(x='badger', y=42, z=False)),
+        ('- X', NS(x='X', y=42, z=False)),
+        ('+ -3', NS(x=None, y=-3, z=False)),
+        ('-+-', NS(x=None, y=42, z=True)),
+        ('- ===', NS(x='===', y=42, z=False)),
+    ]
+
+
+class TestNargsZeroOrMore(ParserTestCase):
+    """Tests specifying an args for an Optional that accepts zero or more"""
+
+    argument_signatures = [Sig('-x', nargs='*'), Sig('y', nargs='*')]
+    failures = []
+    successes = [
+        ('', NS(x=None, y=[])),
+        ('-x', NS(x=[], y=[])),
+        ('-x a', NS(x=['a'], y=[])),
+        ('-x a -- b', NS(x=['a'], y=['b'])),
+        ('a', NS(x=None, y=['a'])),
+        ('a -x', NS(x=[], y=['a'])),
+        ('a -x b', NS(x=['b'], y=['a'])),
+    ]
+
+
+class TestNargsRemainder(ParserTestCase):
+    """Tests specifying a positional with nargs=REMAINDER"""
+
+    argument_signatures = [Sig('x'), Sig('y', nargs='...'), Sig('-z')]
+    failures = ['', '-z', '-z Z']
+    successes = [
+        ('X', NS(x='X', y=[], z=None)),
+        ('-z Z X', NS(x='X', y=[], z='Z')),
+        ('X A B -z Z', NS(x='X', y=['A', 'B', '-z', 'Z'], z=None)),
+        ('X Y --foo', NS(x='X', y=['Y', '--foo'], z=None)),
+    ]
+
+
+class TestOptionLike(ParserTestCase):
+    """Tests options that may or may not be arguments"""
+
+    argument_signatures = [
+        Sig('-x', type=float),
+        Sig('-3', type=float, dest='y'),
+        Sig('z', nargs='*'),
+    ]
+    failures = ['-x', '-y2.5', '-xa', '-x -a',
+                '-x -3', '-x -3.5', '-3 -3.5',
+                '-x -2.5', '-x -2.5 a', '-3 -.5',
+                'a x -1', '-x -1 a', '-3 -1 a']
+    successes = [
+        ('', NS(x=None, y=None, z=[])),
+        ('-x 2.5', NS(x=2.5, y=None, z=[])),
+        ('-x 2.5 a', NS(x=2.5, y=None, z=['a'])),
+        ('-3.5', NS(x=None, y=0.5, z=[])),
+        ('-3-.5', NS(x=None, y=-0.5, z=[])),
+        ('-3 .5', NS(x=None, y=0.5, z=[])),
+        ('a -3.5', NS(x=None, y=0.5, z=['a'])),
+        ('a', NS(x=None, y=None, z=['a'])),
+        ('a -x 1', NS(x=1.0, y=None, z=['a'])),
+        ('-x 1 a', NS(x=1.0, y=None, z=['a'])),
+        ('-3 1 a', NS(x=None, y=1.0, z=['a'])),
+    ]
+
+
+class TestDefaultSuppress(ParserTestCase):
+    """Test actions with suppressed defaults"""
+
+    argument_signatures = [
+        Sig('foo', nargs='?', default=argparse.SUPPRESS),
+        Sig('bar', nargs='*', default=argparse.SUPPRESS),
+        Sig('--baz', action='store_true', default=argparse.SUPPRESS),
+    ]
+    failures = ['-x']
+    successes = [
+        ('', NS()),
+        ('a', NS(foo='a')),
+        ('a b', NS(foo='a', bar=['b'])),
+        ('--baz', NS(baz=True)),
+        ('a --baz', NS(foo='a', baz=True)),
+        ('--baz a b', NS(foo='a', bar=['b'], baz=True)),
+    ]
+
+
+class TestParserDefaultSuppress(ParserTestCase):
+    """Test actions with a parser-level default of SUPPRESS"""
+
+    parser_signature = Sig(argument_default=argparse.SUPPRESS)
+    argument_signatures = [
+        Sig('foo', nargs='?'),
+        Sig('bar', nargs='*'),
+        Sig('--baz', action='store_true'),
+    ]
+    failures = ['-x']
+    successes = [
+        ('', NS()),
+        ('a', NS(foo='a')),
+        ('a b', NS(foo='a', bar=['b'])),
+        ('--baz', NS(baz=True)),
+        ('a --baz', NS(foo='a', baz=True)),
+        ('--baz a b', NS(foo='a', bar=['b'], baz=True)),
+    ]
+
+
+class TestParserDefault42(ParserTestCase):
+    """Test actions with a parser-level default of 42"""
+
+    parser_signature = Sig(argument_default=42, version='1.0')
+    argument_signatures = [
+        Sig('foo', nargs='?'),
+        Sig('bar', nargs='*'),
+        Sig('--baz', action='store_true'),
+    ]
+    failures = ['-x']
+    successes = [
+        ('', NS(foo=42, bar=42, baz=42)),
+        ('a', NS(foo='a', bar=42, baz=42)),
+        ('a b', NS(foo='a', bar=['b'], baz=42)),
+        ('--baz', NS(foo=42, bar=42, baz=True)),
+        ('a --baz', NS(foo='a', bar=42, baz=True)),
+        ('--baz a b', NS(foo='a', bar=['b'], baz=True)),
+    ]
+
+
+class TestArgumentsFromFile(TempDirMixin, ParserTestCase):
+    """Test reading arguments from a file"""
+
+    def setUp(self):
+        super(TestArgumentsFromFile, self).setUp()
+        file_texts = [
+            ('hello', 'hello world!\n'),
+            ('recursive', '-a\n'
+                          'A\n'
+                          '@hello'),
+            ('invalid', '@no-such-path\n'),
+        ]
+        for path, text in file_texts:
+            file = open(path, 'w')
+            file.write(text)
+            file.close()
+
+    parser_signature = Sig(fromfile_prefix_chars='@')
+    argument_signatures = [
+        Sig('-a'),
+        Sig('x'),
+        Sig('y', nargs='+'),
+    ]
+    failures = ['', '-b', 'X', '@invalid', '@missing']
+    successes = [
+        ('X Y', NS(a=None, x='X', y=['Y'])),
+        ('X -a A Y Z', NS(a='A', x='X', y=['Y', 'Z'])),
+        ('@hello X', NS(a=None, x='hello world!', y=['X'])),
+        ('X @hello', NS(a=None, x='X', y=['hello world!'])),
+        ('-a B @recursive Y Z', NS(a='A', x='hello world!', y=['Y', 'Z'])),
+        ('X @recursive Z -a B', NS(a='B', x='X', y=['hello world!', 'Z'])),
+    ]
+
+
+class TestArgumentsFromFileConverter(TempDirMixin, ParserTestCase):
+    """Test reading arguments from a file"""
+
+    def setUp(self):
+        super(TestArgumentsFromFileConverter, self).setUp()
+        file_texts = [
+            ('hello', 'hello world!\n'),
+        ]
+        for path, text in file_texts:
+            file = open(path, 'w')
+            file.write(text)
+            file.close()
+
+    class FromFileConverterArgumentParser(ErrorRaisingArgumentParser):
+
+        def convert_arg_line_to_args(self, arg_line):
+            for arg in arg_line.split():
+                if not arg.strip():
+                    continue
+                yield arg
+    parser_class = FromFileConverterArgumentParser
+    parser_signature = Sig(fromfile_prefix_chars='@')
+    argument_signatures = [
+        Sig('y', nargs='+'),
+    ]
+    failures = []
+    successes = [
+        ('@hello X', NS(y=['hello', 'world!', 'X'])),
+    ]
+
+
+# =====================
+# Type conversion tests
+# =====================
+
+class TestFileTypeRepr(TestCase):
+
+    def test_r(self):
+        type = argparse.FileType('r')
+        self.assertEqual("FileType('r')", repr(type))
+
+    def test_wb_1(self):
+        type = argparse.FileType('wb', 1)
+        self.assertEqual("FileType('wb', 1)", repr(type))
+
+
+class RFile(object):
+    seen = {}
+
+    def __init__(self, name):
+        self.name = name
+
+    __hash__ = None
+
+    def __eq__(self, other):
+        if other in self.seen:
+            text = self.seen[other]
+        else:
+            text = self.seen[other] = other.read()
+            other.close()
+        if not isinstance(text, str):
+            text = text.decode('ascii')
+        return self.name == other.name == text
+
+
+class TestFileTypeR(TempDirMixin, ParserTestCase):
+    """Test the FileType option/argument type for reading files"""
+
+    def setUp(self):
+        super(TestFileTypeR, self).setUp()
+        for file_name in ['foo', 'bar']:
+            file = open(os.path.join(self.temp_dir, file_name), 'w')
+            file.write(file_name)
+            file.close()
+
+    argument_signatures = [
+        Sig('-x', type=argparse.FileType()),
+        Sig('spam', type=argparse.FileType('r')),
+    ]
+    failures = ['-x', '-x bar']
+    successes = [
+        ('foo', NS(x=None, spam=RFile('foo'))),
+        ('-x foo bar', NS(x=RFile('foo'), spam=RFile('bar'))),
+        ('bar -x foo', NS(x=RFile('foo'), spam=RFile('bar'))),
+        ('-x - -', NS(x=sys.stdin, spam=sys.stdin)),
+    ]
+
+
+class TestFileTypeRB(TempDirMixin, ParserTestCase):
+    """Test the FileType option/argument type for reading files"""
+
+    def setUp(self):
+        super(TestFileTypeRB, self).setUp()
+        for file_name in ['foo', 'bar']:
+            file = open(os.path.join(self.temp_dir, file_name), 'w')
+            file.write(file_name)
+            file.close()
+
+    argument_signatures = [
+        Sig('-x', type=argparse.FileType('rb')),
+        Sig('spam', type=argparse.FileType('rb')),
+    ]
+    failures = ['-x', '-x bar']
+    successes = [
+        ('foo', NS(x=None, spam=RFile('foo'))),
+        ('-x foo bar', NS(x=RFile('foo'), spam=RFile('bar'))),
+        ('bar -x foo', NS(x=RFile('foo'), spam=RFile('bar'))),
+        ('-x - -', NS(x=sys.stdin, spam=sys.stdin)),
+    ]
+
+
+class WFile(object):
+    seen = set()
+
+    def __init__(self, name):
+        self.name = name
+
+    __hash__ = None
+
+    def __eq__(self, other):
+        if other not in self.seen:
+            text = 'Check that file is writable.'
+            if 'b' in other.mode:
+                text = text.encode('ascii')
+            other.write(text)
+            other.close()
+            self.seen.add(other)
+        return self.name == other.name
+
+
+class TestFileTypeW(TempDirMixin, ParserTestCase):
+    """Test the FileType option/argument type for writing files"""
+
+    argument_signatures = [
+        Sig('-x', type=argparse.FileType('w')),
+        Sig('spam', type=argparse.FileType('w')),
+    ]
+    failures = ['-x', '-x bar']
+    successes = [
+        ('foo', NS(x=None, spam=WFile('foo'))),
+        ('-x foo bar', NS(x=WFile('foo'), spam=WFile('bar'))),
+        ('bar -x foo', NS(x=WFile('foo'), spam=WFile('bar'))),
+        ('-x - -', NS(x=sys.stdout, spam=sys.stdout)),
+    ]
+
+
+class TestFileTypeWB(TempDirMixin, ParserTestCase):
+
+    argument_signatures = [
+        Sig('-x', type=argparse.FileType('wb')),
+        Sig('spam', type=argparse.FileType('wb')),
+    ]
+    failures = ['-x', '-x bar']
+    successes = [
+        ('foo', NS(x=None, spam=WFile('foo'))),
+        ('-x foo bar', NS(x=WFile('foo'), spam=WFile('bar'))),
+        ('bar -x foo', NS(x=WFile('foo'), spam=WFile('bar'))),
+        ('-x - -', NS(x=sys.stdout, spam=sys.stdout)),
+    ]
+
+
+class TestTypeCallable(ParserTestCase):
+    """Test some callables as option/argument types"""
+
+    argument_signatures = [
+        Sig('--eggs', type=complex),
+        Sig('spam', type=float),
+    ]
+    failures = ['a', '42j', '--eggs a', '--eggs 2i']
+    successes = [
+        ('--eggs=42 42', NS(eggs=42, spam=42.0)),
+        ('--eggs 2j -- -1.5', NS(eggs=2j, spam=-1.5)),
+        ('1024.675', NS(eggs=None, spam=1024.675)),
+    ]
+
+
+class TestTypeUserDefined(ParserTestCase):
+    """Test a user-defined option/argument type"""
+
+    class MyType(TestCase):
+
+        def __init__(self, value):
+            self.value = value
+
+        __hash__ = None
+
+        def __eq__(self, other):
+            return (type(self), self.value) == (type(other), other.value)
+
+    argument_signatures = [
+        Sig('-x', type=MyType),
+        Sig('spam', type=MyType),
+    ]
+    failures = []
+    successes = [
+        ('a -x b', NS(x=MyType('b'), spam=MyType('a'))),
+        ('-xf g', NS(x=MyType('f'), spam=MyType('g'))),
+    ]
+
+
+class TestTypeClassicClass(ParserTestCase):
+    """Test a classic class type"""
+
+    class C:
+
+        def __init__(self, value):
+            self.value = value
+
+        __hash__ = None
+
+        def __eq__(self, other):
+            return (type(self), self.value) == (type(other), other.value)
+
+    argument_signatures = [
+        Sig('-x', type=C),
+        Sig('spam', type=C),
+    ]
+    failures = []
+    successes = [
+        ('a -x b', NS(x=C('b'), spam=C('a'))),
+        ('-xf g', NS(x=C('f'), spam=C('g'))),
+    ]
+
+
+class TestTypeRegistration(TestCase):
+    """Test a user-defined type by registering it"""
+
+    def test(self):
+
+        def get_my_type(string):
+            return 'my_type{%s}' % string
+
+        parser = argparse.ArgumentParser()
+        parser.register('type', 'my_type', get_my_type)
+        parser.add_argument('-x', type='my_type')
+        parser.add_argument('y', type='my_type')
+
+        self.assertEqual(parser.parse_args('1'.split()),
+                         NS(x=None, y='my_type{1}'))
+        self.assertEqual(parser.parse_args('-x 1 42'.split()),
+                         NS(x='my_type{1}', y='my_type{42}'))
+
+
+# ============
+# Action tests
+# ============
+
+class TestActionUserDefined(ParserTestCase):
+    """Test a user-defined option/argument action"""
+
+    class OptionalAction(argparse.Action):
+
+        def __call__(self, parser, namespace, value, option_string=None):
+            try:
+                # check destination and option string
+                assert self.dest == 'spam', 'dest: %s' % self.dest
+                assert option_string == '-s', 'flag: %s' % option_string
+                # when option is before argument, badger=2, and when
+                # option is after argument, badger=<whatever was set>
+                expected_ns = NS(spam=0.25)
+                if value in [0.125, 0.625]:
+                    expected_ns.badger = 2
+                elif value in [2.0]:
+                    expected_ns.badger = 84
+                else:
+                    raise AssertionError('value: %s' % value)
+                assert expected_ns == namespace, ('expected %s, got %s' %
+                                                  (expected_ns, namespace))
+            except AssertionError:
+                e = sys.exc_info()[1]
+                raise ArgumentParserError('opt_action failed: %s' % e)
+            setattr(namespace, 'spam', value)
+
+    class PositionalAction(argparse.Action):
+
+        def __call__(self, parser, namespace, value, option_string=None):
+            try:
+                assert option_string is None, ('option_string: %s' %
+                                               option_string)
+                # check destination
+                assert self.dest == 'badger', 'dest: %s' % self.dest
+                # when argument is before option, spam=0.25, and when
+                # option is after argument, spam=<whatever was set>
+                expected_ns = NS(badger=2)
+                if value in [42, 84]:
+                    expected_ns.spam = 0.25
+                elif value in [1]:
+                    expected_ns.spam = 0.625
+                elif value in [2]:
+                    expected_ns.spam = 0.125
+                else:
+                    raise AssertionError('value: %s' % value)
+                assert expected_ns == namespace, ('expected %s, got %s' %
+                                                  (expected_ns, namespace))
+            except AssertionError:
+                e = sys.exc_info()[1]
+                raise ArgumentParserError('arg_action failed: %s' % e)
+            setattr(namespace, 'badger', value)
+
+    argument_signatures = [
+        Sig('-s', dest='spam', action=OptionalAction,
+            type=float, default=0.25),
+        Sig('badger', action=PositionalAction,
+            type=int, nargs='?', default=2),
+    ]
+    failures = []
+    successes = [
+        ('-s0.125', NS(spam=0.125, badger=2)),
+        ('42', NS(spam=0.25, badger=42)),
+        ('-s 0.625 1', NS(spam=0.625, badger=1)),
+        ('84 -s2', NS(spam=2.0, badger=84)),
+    ]
+
+
+class TestActionRegistration(TestCase):
+    """Test a user-defined action supplied by registering it"""
+
+    class MyAction(argparse.Action):
+
+        def __call__(self, parser, namespace, values, option_string=None):
+            setattr(namespace, self.dest, 'foo[%s]' % values)
+
+    def test(self):
+
+        parser = argparse.ArgumentParser()
+        parser.register('action', 'my_action', self.MyAction)
+        parser.add_argument('badger', action='my_action')
+
+        self.assertEqual(parser.parse_args(['1']), NS(badger='foo[1]'))
+        self.assertEqual(parser.parse_args(['42']), NS(badger='foo[42]'))
+
+
+# ================
+# Subparsers tests
+# ================
+
+class TestAddSubparsers(TestCase):
+    """Test the add_subparsers method"""
+
+    def assertArgumentParserError(self, *args, **kwargs):
+        self.assertRaises(ArgumentParserError, *args, **kwargs)
+
+    def _get_parser(self, subparser_help=False, prefix_chars=None):
+        # create a parser with a subparsers argument
+        if prefix_chars:
+            parser = ErrorRaisingArgumentParser(
+                prog='PROG', description='main description', prefix_chars=prefix_chars)
+            parser.add_argument(
+                prefix_chars[0] * 2 + 'foo', action='store_true', help='foo help')
+        else:
+            parser = ErrorRaisingArgumentParser(
+                prog='PROG', description='main description')
+            parser.add_argument(
+                '--foo', action='store_true', help='foo help')
+        parser.add_argument(
+            'bar', type=float, help='bar help')
+
+        # check that only one subparsers argument can be added
+        subparsers = parser.add_subparsers(help='command help')
+        self.assertArgumentParserError(parser.add_subparsers)
+
+        # add first sub-parser
+        parser1_kwargs = dict(description='1 description')
+        if subparser_help:
+            parser1_kwargs['help'] = '1 help'
+        parser1 = subparsers.add_parser('1', **parser1_kwargs)
+        parser1.add_argument('-w', type=int, help='w help')
+        parser1.add_argument('x', choices='abc', help='x help')
+
+        # add second sub-parser
+        parser2_kwargs = dict(description='2 description')
+        if subparser_help:
+            parser2_kwargs['help'] = '2 help'
+        parser2 = subparsers.add_parser('2', **parser2_kwargs)
+        parser2.add_argument('-y', choices='123', help='y help')
+        parser2.add_argument('z', type=complex, nargs='*', help='z help')
+
+        # return the main parser
+        return parser
+
+    def setUp(self):
+        super(TestAddSubparsers, self).setUp()
+        self.parser = self._get_parser()
+        self.command_help_parser = self._get_parser(subparser_help=True)
+
+    def test_parse_args_failures(self):
+        # check some failure cases:
+        for args_str in ['', 'a', 'a a', '0.5 a', '0.5 1',
+                         '0.5 1 -y', '0.5 2 -w']:
+            args = args_str.split()
+            self.assertArgumentParserError(self.parser.parse_args, args)
+
+    def test_parse_args(self):
+        # check some non-failure cases:
+        self.assertEqual(
+            self.parser.parse_args('0.5 1 b -w 7'.split()),
+            NS(foo=False, bar=0.5, w=7, x='b'),
+        )
+        self.assertEqual(
+            self.parser.parse_args('0.25 --foo 2 -y 2 3j -- -1j'.split()),
+            NS(foo=True, bar=0.25, y='2', z=[3j, -1j]),
+        )
+        self.assertEqual(
+            self.parser.parse_args('--foo 0.125 1 c'.split()),
+            NS(foo=True, bar=0.125, w=None, x='c'),
+        )
+
+    def test_parse_known_args(self):
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 1 b -w 7'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), []),
+        )
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 -p 1 b -w 7'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), ['-p']),
+        )
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 1 b -w 7 -p'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), ['-p']),
+        )
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 1 b -q -rs -w 7'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), ['-q', '-rs']),
+        )
+        self.assertEqual(
+            self.parser.parse_known_args('0.5 -W 1 b -X Y -w 7 Z'.split()),
+            (NS(foo=False, bar=0.5, w=7, x='b'), ['-W', '-X', 'Y', 'Z']),
+        )
+
+    def test_dest(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.add_argument('--foo', action='store_true')
+        subparsers = parser.add_subparsers(dest='bar')
+        parser1 = subparsers.add_parser('1')
+        parser1.add_argument('baz')
+        self.assertEqual(NS(foo=False, bar='1', baz='2'),
+                         parser.parse_args('1 2'.split()))
+
+    def test_help(self):
+        self.assertEqual(self.parser.format_usage(),
+                         'usage: PROG [-h] [--foo] bar {1,2} ...\n')
+        self.assertEqual(self.parser.format_help(), textwrap.dedent('''\
+            usage: PROG [-h] [--foo] bar {1,2} ...
+
+            main description
+
+            positional arguments:
+              bar         bar help
+              {1,2}       command help
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              --foo       foo help
+            '''))
+
+    def test_help_extra_prefix_chars(self):
+        # Make sure - is still used for help if it is a non-first prefix char
+        parser = self._get_parser(prefix_chars='+:-')
+        self.assertEqual(parser.format_usage(),
+                         'usage: PROG [-h] [++foo] bar {1,2} ...\n')
+        self.assertEqual(parser.format_help(), textwrap.dedent('''\
+            usage: PROG [-h] [++foo] bar {1,2} ...
+
+            main description
+
+            positional arguments:
+              bar         bar help
+              {1,2}       command help
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              ++foo       foo help
+            '''))
+
+
+    def test_help_alternate_prefix_chars(self):
+        parser = self._get_parser(prefix_chars='+:/')
+        self.assertEqual(parser.format_usage(),
+                         'usage: PROG [+h] [++foo] bar {1,2} ...\n')
+        self.assertEqual(parser.format_help(), textwrap.dedent('''\
+            usage: PROG [+h] [++foo] bar {1,2} ...
+
+            main description
+
+            positional arguments:
+              bar         bar help
+              {1,2}       command help
+
+            optional arguments:
+              +h, ++help  show this help message and exit
+              ++foo       foo help
+            '''))
+
+    def test_parser_command_help(self):
+        self.assertEqual(self.command_help_parser.format_usage(),
+                         'usage: PROG [-h] [--foo] bar {1,2} ...\n')
+        self.assertEqual(self.command_help_parser.format_help(),
+                         textwrap.dedent('''\
+            usage: PROG [-h] [--foo] bar {1,2} ...
+
+            main description
+
+            positional arguments:
+              bar         bar help
+              {1,2}       command help
+                1         1 help
+                2         2 help
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              --foo       foo help
+            '''))
+
+    def test_subparser_title_help(self):
+        parser = ErrorRaisingArgumentParser(prog='PROG',
+                                            description='main description')
+        parser.add_argument('--foo', action='store_true', help='foo help')
+        parser.add_argument('bar', help='bar help')
+        subparsers = parser.add_subparsers(title='subcommands',
+                                           description='command help',
+                                           help='additional text')
+        parser1 = subparsers.add_parser('1')
+        parser2 = subparsers.add_parser('2')
+        self.assertEqual(parser.format_usage(),
+                         'usage: PROG [-h] [--foo] bar {1,2} ...\n')
+        self.assertEqual(parser.format_help(), textwrap.dedent('''\
+            usage: PROG [-h] [--foo] bar {1,2} ...
+
+            main description
+
+            positional arguments:
+              bar         bar help
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              --foo       foo help
+
+            subcommands:
+              command help
+
+              {1,2}       additional text
+            '''))
+
+    def _test_subparser_help(self, args_str, expected_help):
+        try:
+            self.parser.parse_args(args_str.split())
+        except ArgumentParserError:
+            err = sys.exc_info()[1]
+            if err.stdout != expected_help:
+                print(repr(expected_help))
+                print(repr(err.stdout))
+            self.assertEqual(err.stdout, expected_help)
+
+    def test_subparser1_help(self):
+        self._test_subparser_help('5.0 1 -h', textwrap.dedent('''\
+            usage: PROG bar 1 [-h] [-w W] {a,b,c}
+
+            1 description
+
+            positional arguments:
+              {a,b,c}     x help
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              -w W        w help
+            '''))
+
+    def test_subparser2_help(self):
+        self._test_subparser_help('5.0 2 -h', textwrap.dedent('''\
+            usage: PROG bar 2 [-h] [-y {1,2,3}] [z [z ...]]
+
+            2 description
+
+            positional arguments:
+              z           z help
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              -y {1,2,3}  y help
+            '''))
+
+# ============
+# Groups tests
+# ============
+
+class TestPositionalsGroups(TestCase):
+    """Tests that order of group positionals matches construction order"""
+
+    def test_nongroup_first(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.add_argument('foo')
+        group = parser.add_argument_group('g')
+        group.add_argument('bar')
+        parser.add_argument('baz')
+        expected = NS(foo='1', bar='2', baz='3')
+        result = parser.parse_args('1 2 3'.split())
+        self.assertEqual(expected, result)
+
+    def test_group_first(self):
+        parser = ErrorRaisingArgumentParser()
+        group = parser.add_argument_group('xxx')
+        group.add_argument('foo')
+        parser.add_argument('bar')
+        parser.add_argument('baz')
+        expected = NS(foo='1', bar='2', baz='3')
+        result = parser.parse_args('1 2 3'.split())
+        self.assertEqual(expected, result)
+
+    def test_interleaved_groups(self):
+        parser = ErrorRaisingArgumentParser()
+        group = parser.add_argument_group('xxx')
+        parser.add_argument('foo')
+        group.add_argument('bar')
+        parser.add_argument('baz')
+        group = parser.add_argument_group('yyy')
+        group.add_argument('frell')
+        expected = NS(foo='1', bar='2', baz='3', frell='4')
+        result = parser.parse_args('1 2 3 4'.split())
+        self.assertEqual(expected, result)
+
+# ===================
+# Parent parser tests
+# ===================
+
+class TestParentParsers(TestCase):
+    """Tests that parsers can be created with parent parsers"""
+
+    def assertArgumentParserError(self, *args, **kwargs):
+        self.assertRaises(ArgumentParserError, *args, **kwargs)
+
+    def setUp(self):
+        super(TestParentParsers, self).setUp()
+        self.wxyz_parent = ErrorRaisingArgumentParser(add_help=False)
+        self.wxyz_parent.add_argument('--w')
+        x_group = self.wxyz_parent.add_argument_group('x')
+        x_group.add_argument('-y')
+        self.wxyz_parent.add_argument('z')
+
+        self.abcd_parent = ErrorRaisingArgumentParser(add_help=False)
+        self.abcd_parent.add_argument('a')
+        self.abcd_parent.add_argument('-b')
+        c_group = self.abcd_parent.add_argument_group('c')
+        c_group.add_argument('--d')
+
+        self.w_parent = ErrorRaisingArgumentParser(add_help=False)
+        self.w_parent.add_argument('--w')
+
+        self.z_parent = ErrorRaisingArgumentParser(add_help=False)
+        self.z_parent.add_argument('z')
+
+        # parents with mutually exclusive groups
+        self.ab_mutex_parent = ErrorRaisingArgumentParser(add_help=False)
+        group = self.ab_mutex_parent.add_mutually_exclusive_group()
+        group.add_argument('-a', action='store_true')
+        group.add_argument('-b', action='store_true')
+
+        self.main_program = os.path.basename(sys.argv[0])
+
+    def test_single_parent(self):
+        parser = ErrorRaisingArgumentParser(parents=[self.wxyz_parent])
+        self.assertEqual(parser.parse_args('-y 1 2 --w 3'.split()),
+                         NS(w='3', y='1', z='2'))
+
+    def test_single_parent_mutex(self):
+        self._test_mutex_ab(self.ab_mutex_parent.parse_args)
+        parser = ErrorRaisingArgumentParser(parents=[self.ab_mutex_parent])
+        self._test_mutex_ab(parser.parse_args)
+
+    def test_single_granparent_mutex(self):
+        parents = [self.ab_mutex_parent]
+        parser = ErrorRaisingArgumentParser(add_help=False, parents=parents)
+        parser = ErrorRaisingArgumentParser(parents=[parser])
+        self._test_mutex_ab(parser.parse_args)
+
+    def _test_mutex_ab(self, parse_args):
+        self.assertEqual(parse_args([]), NS(a=False, b=False))
+        self.assertEqual(parse_args(['-a']), NS(a=True, b=False))
+        self.assertEqual(parse_args(['-b']), NS(a=False, b=True))
+        self.assertArgumentParserError(parse_args, ['-a', '-b'])
+        self.assertArgumentParserError(parse_args, ['-b', '-a'])
+        self.assertArgumentParserError(parse_args, ['-c'])
+        self.assertArgumentParserError(parse_args, ['-a', '-c'])
+        self.assertArgumentParserError(parse_args, ['-b', '-c'])
+
+    def test_multiple_parents(self):
+        parents = [self.abcd_parent, self.wxyz_parent]
+        parser = ErrorRaisingArgumentParser(parents=parents)
+        self.assertEqual(parser.parse_args('--d 1 --w 2 3 4'.split()),
+                         NS(a='3', b=None, d='1', w='2', y=None, z='4'))
+
+    def test_multiple_parents_mutex(self):
+        parents = [self.ab_mutex_parent, self.wxyz_parent]
+        parser = ErrorRaisingArgumentParser(parents=parents)
+        self.assertEqual(parser.parse_args('-a --w 2 3'.split()),
+                         NS(a=True, b=False, w='2', y=None, z='3'))
+        self.assertArgumentParserError(
+            parser.parse_args, '-a --w 2 3 -b'.split())
+        self.assertArgumentParserError(
+            parser.parse_args, '-a -b --w 2 3'.split())
+
+    def test_conflicting_parents(self):
+        self.assertRaises(
+            argparse.ArgumentError,
+            argparse.ArgumentParser,
+            parents=[self.w_parent, self.wxyz_parent])
+
+    def test_conflicting_parents_mutex(self):
+        self.assertRaises(
+            argparse.ArgumentError,
+            argparse.ArgumentParser,
+            parents=[self.abcd_parent, self.ab_mutex_parent])
+
+    def test_same_argument_name_parents(self):
+        parents = [self.wxyz_parent, self.z_parent]
+        parser = ErrorRaisingArgumentParser(parents=parents)
+        self.assertEqual(parser.parse_args('1 2'.split()),
+                         NS(w=None, y=None, z='2'))
+
+    def test_subparser_parents(self):
+        parser = ErrorRaisingArgumentParser()
+        subparsers = parser.add_subparsers()
+        abcde_parser = subparsers.add_parser('bar', parents=[self.abcd_parent])
+        abcde_parser.add_argument('e')
+        self.assertEqual(parser.parse_args('bar -b 1 --d 2 3 4'.split()),
+                         NS(a='3', b='1', d='2', e='4'))
+
+    def test_subparser_parents_mutex(self):
+        parser = ErrorRaisingArgumentParser()
+        subparsers = parser.add_subparsers()
+        parents = [self.ab_mutex_parent]
+        abc_parser = subparsers.add_parser('foo', parents=parents)
+        c_group = abc_parser.add_argument_group('c_group')
+        c_group.add_argument('c')
+        parents = [self.wxyz_parent, self.ab_mutex_parent]
+        wxyzabe_parser = subparsers.add_parser('bar', parents=parents)
+        wxyzabe_parser.add_argument('e')
+        self.assertEqual(parser.parse_args('foo -a 4'.split()),
+                         NS(a=True, b=False, c='4'))
+        self.assertEqual(parser.parse_args('bar -b  --w 2 3 4'.split()),
+                         NS(a=False, b=True, w='2', y=None, z='3', e='4'))
+        self.assertArgumentParserError(
+            parser.parse_args, 'foo -a -b 4'.split())
+        self.assertArgumentParserError(
+            parser.parse_args, 'bar -b -a 4'.split())
+
+    def test_parent_help(self):
+        parents = [self.abcd_parent, self.wxyz_parent]
+        parser = ErrorRaisingArgumentParser(parents=parents)
+        parser_help = parser.format_help()
+        self.assertEqual(parser_help, textwrap.dedent('''\
+            usage: {} [-h] [-b B] [--d D] [--w W] [-y Y] a z
+
+            positional arguments:
+              a
+              z
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              -b B
+              --w W
+
+            c:
+              --d D
+
+            x:
+              -y Y
+        '''.format(self.main_program)))
+
+    def test_groups_parents(self):
+        parent = ErrorRaisingArgumentParser(add_help=False)
+        g = parent.add_argument_group(title='g', description='gd')
+        g.add_argument('-w')
+        g.add_argument('-x')
+        m = parent.add_mutually_exclusive_group()
+        m.add_argument('-y')
+        m.add_argument('-z')
+        parser = ErrorRaisingArgumentParser(parents=[parent])
+
+        self.assertRaises(ArgumentParserError, parser.parse_args,
+            ['-y', 'Y', '-z', 'Z'])
+
+        parser_help = parser.format_help()
+        self.assertEqual(parser_help, textwrap.dedent('''\
+            usage: {} [-h] [-w W] [-x X] [-y Y | -z Z]
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              -y Y
+              -z Z
+
+            g:
+              gd
+
+              -w W
+              -x X
+        '''.format(self.main_program)))
+
+# ==============================
+# Mutually exclusive group tests
+# ==============================
+
+class TestMutuallyExclusiveGroupErrors(TestCase):
+
+    def test_invalid_add_argument_group(self):
+        parser = ErrorRaisingArgumentParser()
+        raises = self.assertRaises
+        raises(TypeError, parser.add_mutually_exclusive_group, title='foo')
+
+    def test_invalid_add_argument(self):
+        parser = ErrorRaisingArgumentParser()
+        group = parser.add_mutually_exclusive_group()
+        add_argument = group.add_argument
+        raises = self.assertRaises
+        raises(ValueError, add_argument, '--foo', required=True)
+        raises(ValueError, add_argument, 'bar')
+        raises(ValueError, add_argument, 'bar', nargs='+')
+        raises(ValueError, add_argument, 'bar', nargs=1)
+        raises(ValueError, add_argument, 'bar', nargs=argparse.PARSER)
+
+    def test_help(self):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        group1 = parser.add_mutually_exclusive_group()
+        group1.add_argument('--foo', action='store_true')
+        group1.add_argument('--bar', action='store_false')
+        group2 = parser.add_mutually_exclusive_group()
+        group2.add_argument('--soup', action='store_true')
+        group2.add_argument('--nuts', action='store_false')
+        expected = '''\
+            usage: PROG [-h] [--foo | --bar] [--soup | --nuts]
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              --foo
+              --bar
+              --soup
+              --nuts
+              '''
+        self.assertEqual(parser.format_help(), textwrap.dedent(expected))
+
+class MEMixin(object):
+
+    def test_failures_when_not_required(self):
+        parse_args = self.get_parser(required=False).parse_args
+        error = ArgumentParserError
+        for args_string in self.failures:
+            self.assertRaises(error, parse_args, args_string.split())
+
+    def test_failures_when_required(self):
+        parse_args = self.get_parser(required=True).parse_args
+        error = ArgumentParserError
+        for args_string in self.failures + ['']:
+            self.assertRaises(error, parse_args, args_string.split())
+
+    def test_successes_when_not_required(self):
+        parse_args = self.get_parser(required=False).parse_args
+        successes = self.successes + self.successes_when_not_required
+        for args_string, expected_ns in successes:
+            actual_ns = parse_args(args_string.split())
+            self.assertEqual(actual_ns, expected_ns)
+
+    def test_successes_when_required(self):
+        parse_args = self.get_parser(required=True).parse_args
+        for args_string, expected_ns in self.successes:
+            actual_ns = parse_args(args_string.split())
+            self.assertEqual(actual_ns, expected_ns)
+
+    def test_usage_when_not_required(self):
+        format_usage = self.get_parser(required=False).format_usage
+        expected_usage = self.usage_when_not_required
+        self.assertEqual(format_usage(), textwrap.dedent(expected_usage))
+
+    def test_usage_when_required(self):
+        format_usage = self.get_parser(required=True).format_usage
+        expected_usage = self.usage_when_required
+        self.assertEqual(format_usage(), textwrap.dedent(expected_usage))
+
+    def test_help_when_not_required(self):
+        format_help = self.get_parser(required=False).format_help
+        help = self.usage_when_not_required + self.help
+        self.assertEqual(format_help(), textwrap.dedent(help))
+
+    def test_help_when_required(self):
+        format_help = self.get_parser(required=True).format_help
+        help = self.usage_when_required + self.help
+        self.assertEqual(format_help(), textwrap.dedent(help))
+
+
+class TestMutuallyExclusiveSimple(MEMixin, TestCase):
+
+    def get_parser(self, required=None):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        group = parser.add_mutually_exclusive_group(required=required)
+        group.add_argument('--bar', help='bar help')
+        group.add_argument('--baz', nargs='?', const='Z', help='baz help')
+        return parser
+
+    failures = ['--bar X --baz Y', '--bar X --baz']
+    successes = [
+        ('--bar X', NS(bar='X', baz=None)),
+        ('--bar X --bar Z', NS(bar='Z', baz=None)),
+        ('--baz Y', NS(bar=None, baz='Y')),
+        ('--baz', NS(bar=None, baz='Z')),
+    ]
+    successes_when_not_required = [
+        ('', NS(bar=None, baz=None)),
+    ]
+
+    usage_when_not_required = '''\
+        usage: PROG [-h] [--bar BAR | --baz [BAZ]]
+        '''
+    usage_when_required = '''\
+        usage: PROG [-h] (--bar BAR | --baz [BAZ])
+        '''
+    help = '''\
+
+        optional arguments:
+          -h, --help   show this help message and exit
+          --bar BAR    bar help
+          --baz [BAZ]  baz help
+        '''
+
+
+class TestMutuallyExclusiveLong(MEMixin, TestCase):
+
+    def get_parser(self, required=None):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        parser.add_argument('--abcde', help='abcde help')
+        parser.add_argument('--fghij', help='fghij help')
+        group = parser.add_mutually_exclusive_group(required=required)
+        group.add_argument('--klmno', help='klmno help')
+        group.add_argument('--pqrst', help='pqrst help')
+        return parser
+
+    failures = ['--klmno X --pqrst Y']
+    successes = [
+        ('--klmno X', NS(abcde=None, fghij=None, klmno='X', pqrst=None)),
+        ('--abcde Y --klmno X',
+            NS(abcde='Y', fghij=None, klmno='X', pqrst=None)),
+        ('--pqrst X', NS(abcde=None, fghij=None, klmno=None, pqrst='X')),
+        ('--pqrst X --fghij Y',
+            NS(abcde=None, fghij='Y', klmno=None, pqrst='X')),
+    ]
+    successes_when_not_required = [
+        ('', NS(abcde=None, fghij=None, klmno=None, pqrst=None)),
+    ]
+
+    usage_when_not_required = '''\
+    usage: PROG [-h] [--abcde ABCDE] [--fghij FGHIJ]
+                [--klmno KLMNO | --pqrst PQRST]
+    '''
+    usage_when_required = '''\
+    usage: PROG [-h] [--abcde ABCDE] [--fghij FGHIJ]
+                (--klmno KLMNO | --pqrst PQRST)
+    '''
+    help = '''\
+
+    optional arguments:
+      -h, --help     show this help message and exit
+      --abcde ABCDE  abcde help
+      --fghij FGHIJ  fghij help
+      --klmno KLMNO  klmno help
+      --pqrst PQRST  pqrst help
+    '''
+
+
+class TestMutuallyExclusiveFirstSuppressed(MEMixin, TestCase):
+
+    def get_parser(self, required):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        group = parser.add_mutually_exclusive_group(required=required)
+        group.add_argument('-x', help=argparse.SUPPRESS)
+        group.add_argument('-y', action='store_false', help='y help')
+        return parser
+
+    failures = ['-x X -y']
+    successes = [
+        ('-x X', NS(x='X', y=True)),
+        ('-x X -x Y', NS(x='Y', y=True)),
+        ('-y', NS(x=None, y=False)),
+    ]
+    successes_when_not_required = [
+        ('', NS(x=None, y=True)),
+    ]
+
+    usage_when_not_required = '''\
+        usage: PROG [-h] [-y]
+        '''
+    usage_when_required = '''\
+        usage: PROG [-h] -y
+        '''
+    help = '''\
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          -y          y help
+        '''
+
+
+class TestMutuallyExclusiveManySuppressed(MEMixin, TestCase):
+
+    def get_parser(self, required):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        group = parser.add_mutually_exclusive_group(required=required)
+        add = group.add_argument
+        add('--spam', action='store_true', help=argparse.SUPPRESS)
+        add('--badger', action='store_false', help=argparse.SUPPRESS)
+        add('--bladder', help=argparse.SUPPRESS)
+        return parser
+
+    failures = [
+        '--spam --badger',
+        '--badger --bladder B',
+        '--bladder B --spam',
+    ]
+    successes = [
+        ('--spam', NS(spam=True, badger=True, bladder=None)),
+        ('--badger', NS(spam=False, badger=False, bladder=None)),
+        ('--bladder B', NS(spam=False, badger=True, bladder='B')),
+        ('--spam --spam', NS(spam=True, badger=True, bladder=None)),
+    ]
+    successes_when_not_required = [
+        ('', NS(spam=False, badger=True, bladder=None)),
+    ]
+
+    usage_when_required = usage_when_not_required = '''\
+        usage: PROG [-h]
+        '''
+    help = '''\
+
+        optional arguments:
+          -h, --help  show this help message and exit
+        '''
+
+
+class TestMutuallyExclusiveOptionalAndPositional(MEMixin, TestCase):
+
+    def get_parser(self, required):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        group = parser.add_mutually_exclusive_group(required=required)
+        group.add_argument('--foo', action='store_true', help='FOO')
+        group.add_argument('--spam', help='SPAM')
+        group.add_argument('badger', nargs='*', default='X', help='BADGER')
+        return parser
+
+    failures = [
+        '--foo --spam S',
+        '--spam S X',
+        'X --foo',
+        'X Y Z --spam S',
+        '--foo X Y',
+    ]
+    successes = [
+        ('--foo', NS(foo=True, spam=None, badger='X')),
+        ('--spam S', NS(foo=False, spam='S', badger='X')),
+        ('X', NS(foo=False, spam=None, badger=['X'])),
+        ('X Y Z', NS(foo=False, spam=None, badger=['X', 'Y', 'Z'])),
+    ]
+    successes_when_not_required = [
+        ('', NS(foo=False, spam=None, badger='X')),
+    ]
+
+    usage_when_not_required = '''\
+        usage: PROG [-h] [--foo | --spam SPAM | badger [badger ...]]
+        '''
+    usage_when_required = '''\
+        usage: PROG [-h] (--foo | --spam SPAM | badger [badger ...])
+        '''
+    help = '''\
+
+        positional arguments:
+          badger       BADGER
+
+        optional arguments:
+          -h, --help   show this help message and exit
+          --foo        FOO
+          --spam SPAM  SPAM
+        '''
+
+
+class TestMutuallyExclusiveOptionalsMixed(MEMixin, TestCase):
+
+    def get_parser(self, required):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        parser.add_argument('-x', action='store_true', help='x help')
+        group = parser.add_mutually_exclusive_group(required=required)
+        group.add_argument('-a', action='store_true', help='a help')
+        group.add_argument('-b', action='store_true', help='b help')
+        parser.add_argument('-y', action='store_true', help='y help')
+        group.add_argument('-c', action='store_true', help='c help')
+        return parser
+
+    failures = ['-a -b', '-b -c', '-a -c', '-a -b -c']
+    successes = [
+        ('-a', NS(a=True, b=False, c=False, x=False, y=False)),
+        ('-b', NS(a=False, b=True, c=False, x=False, y=False)),
+        ('-c', NS(a=False, b=False, c=True, x=False, y=False)),
+        ('-a -x', NS(a=True, b=False, c=False, x=True, y=False)),
+        ('-y -b', NS(a=False, b=True, c=False, x=False, y=True)),
+        ('-x -y -c', NS(a=False, b=False, c=True, x=True, y=True)),
+    ]
+    successes_when_not_required = [
+        ('', NS(a=False, b=False, c=False, x=False, y=False)),
+        ('-x', NS(a=False, b=False, c=False, x=True, y=False)),
+        ('-y', NS(a=False, b=False, c=False, x=False, y=True)),
+    ]
+
+    usage_when_required = usage_when_not_required = '''\
+        usage: PROG [-h] [-x] [-a] [-b] [-y] [-c]
+        '''
+    help = '''\
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          -x          x help
+          -a          a help
+          -b          b help
+          -y          y help
+          -c          c help
+        '''
+
+
+class TestMutuallyExclusiveOptionalsAndPositionalsMixed(MEMixin, TestCase):
+
+    def get_parser(self, required):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        parser.add_argument('x', help='x help')
+        parser.add_argument('-y', action='store_true', help='y help')
+        group = parser.add_mutually_exclusive_group(required=required)
+        group.add_argument('a', nargs='?', help='a help')
+        group.add_argument('-b', action='store_true', help='b help')
+        group.add_argument('-c', action='store_true', help='c help')
+        return parser
+
+    failures = ['X A -b', '-b -c', '-c X A']
+    successes = [
+        ('X A', NS(a='A', b=False, c=False, x='X', y=False)),
+        ('X -b', NS(a=None, b=True, c=False, x='X', y=False)),
+        ('X -c', NS(a=None, b=False, c=True, x='X', y=False)),
+        ('X A -y', NS(a='A', b=False, c=False, x='X', y=True)),
+        ('X -y -b', NS(a=None, b=True, c=False, x='X', y=True)),
+    ]
+    successes_when_not_required = [
+        ('X', NS(a=None, b=False, c=False, x='X', y=False)),
+        ('X -y', NS(a=None, b=False, c=False, x='X', y=True)),
+    ]
+
+    usage_when_required = usage_when_not_required = '''\
+        usage: PROG [-h] [-y] [-b] [-c] x [a]
+        '''
+    help = '''\
+
+        positional arguments:
+          x           x help
+          a           a help
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          -y          y help
+          -b          b help
+          -c          c help
+        '''
+
+# =================================================
+# Mutually exclusive group in parent parser tests
+# =================================================
+
+class MEPBase(object):
+
+    def get_parser(self, required=None):
+        parent = super(MEPBase, self).get_parser(required=required)
+        parser = ErrorRaisingArgumentParser(
+            prog=parent.prog, add_help=False, parents=[parent])
+        return parser
+
+
+class TestMutuallyExclusiveGroupErrorsParent(
+    MEPBase, TestMutuallyExclusiveGroupErrors):
+    pass
+
+
+class TestMutuallyExclusiveSimpleParent(
+    MEPBase, TestMutuallyExclusiveSimple):
+    pass
+
+
+class TestMutuallyExclusiveLongParent(
+    MEPBase, TestMutuallyExclusiveLong):
+    pass
+
+
+class TestMutuallyExclusiveFirstSuppressedParent(
+    MEPBase, TestMutuallyExclusiveFirstSuppressed):
+    pass
+
+
+class TestMutuallyExclusiveManySuppressedParent(
+    MEPBase, TestMutuallyExclusiveManySuppressed):
+    pass
+
+
+class TestMutuallyExclusiveOptionalAndPositionalParent(
+    MEPBase, TestMutuallyExclusiveOptionalAndPositional):
+    pass
+
+
+class TestMutuallyExclusiveOptionalsMixedParent(
+    MEPBase, TestMutuallyExclusiveOptionalsMixed):
+    pass
+
+
+class TestMutuallyExclusiveOptionalsAndPositionalsMixedParent(
+    MEPBase, TestMutuallyExclusiveOptionalsAndPositionalsMixed):
+    pass
+
+# =================
+# Set default tests
+# =================
+
+class TestSetDefaults(TestCase):
+
+    def test_set_defaults_no_args(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.set_defaults(x='foo')
+        parser.set_defaults(y='bar', z=1)
+        self.assertEqual(NS(x='foo', y='bar', z=1),
+                         parser.parse_args([]))
+        self.assertEqual(NS(x='foo', y='bar', z=1),
+                         parser.parse_args([], NS()))
+        self.assertEqual(NS(x='baz', y='bar', z=1),
+                         parser.parse_args([], NS(x='baz')))
+        self.assertEqual(NS(x='baz', y='bar', z=2),
+                         parser.parse_args([], NS(x='baz', z=2)))
+
+    def test_set_defaults_with_args(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.set_defaults(x='foo', y='bar')
+        parser.add_argument('-x', default='xfoox')
+        self.assertEqual(NS(x='xfoox', y='bar'),
+                         parser.parse_args([]))
+        self.assertEqual(NS(x='xfoox', y='bar'),
+                         parser.parse_args([], NS()))
+        self.assertEqual(NS(x='baz', y='bar'),
+                         parser.parse_args([], NS(x='baz')))
+        self.assertEqual(NS(x='1', y='bar'),
+                         parser.parse_args('-x 1'.split()))
+        self.assertEqual(NS(x='1', y='bar'),
+                         parser.parse_args('-x 1'.split(), NS()))
+        self.assertEqual(NS(x='1', y='bar'),
+                         parser.parse_args('-x 1'.split(), NS(x='baz')))
+
+    def test_set_defaults_subparsers(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.set_defaults(x='foo')
+        subparsers = parser.add_subparsers()
+        parser_a = subparsers.add_parser('a')
+        parser_a.set_defaults(y='bar')
+        self.assertEqual(NS(x='foo', y='bar'),
+                         parser.parse_args('a'.split()))
+
+    def test_set_defaults_parents(self):
+        parent = ErrorRaisingArgumentParser(add_help=False)
+        parent.set_defaults(x='foo')
+        parser = ErrorRaisingArgumentParser(parents=[parent])
+        self.assertEqual(NS(x='foo'), parser.parse_args([]))
+
+    def test_set_defaults_same_as_add_argument(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.set_defaults(w='W', x='X', y='Y', z='Z')
+        parser.add_argument('-w')
+        parser.add_argument('-x', default='XX')
+        parser.add_argument('y', nargs='?')
+        parser.add_argument('z', nargs='?', default='ZZ')
+
+        # defaults set previously
+        self.assertEqual(NS(w='W', x='XX', y='Y', z='ZZ'),
+                         parser.parse_args([]))
+
+        # reset defaults
+        parser.set_defaults(w='WW', x='X', y='YY', z='Z')
+        self.assertEqual(NS(w='WW', x='X', y='YY', z='Z'),
+                         parser.parse_args([]))
+
+    def test_set_defaults_same_as_add_argument_group(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.set_defaults(w='W', x='X', y='Y', z='Z')
+        group = parser.add_argument_group('foo')
+        group.add_argument('-w')
+        group.add_argument('-x', default='XX')
+        group.add_argument('y', nargs='?')
+        group.add_argument('z', nargs='?', default='ZZ')
+
+
+        # defaults set previously
+        self.assertEqual(NS(w='W', x='XX', y='Y', z='ZZ'),
+                         parser.parse_args([]))
+
+        # reset defaults
+        parser.set_defaults(w='WW', x='X', y='YY', z='Z')
+        self.assertEqual(NS(w='WW', x='X', y='YY', z='Z'),
+                         parser.parse_args([]))
+
+# =================
+# Get default tests
+# =================
+
+class TestGetDefault(TestCase):
+
+    def test_get_default(self):
+        parser = ErrorRaisingArgumentParser()
+        self.assertEqual(None, parser.get_default("foo"))
+        self.assertEqual(None, parser.get_default("bar"))
+
+        parser.add_argument("--foo")
+        self.assertEqual(None, parser.get_default("foo"))
+        self.assertEqual(None, parser.get_default("bar"))
+
+        parser.add_argument("--bar", type=int, default=42)
+        self.assertEqual(None, parser.get_default("foo"))
+        self.assertEqual(42, parser.get_default("bar"))
+
+        parser.set_defaults(foo="badger")
+        self.assertEqual("badger", parser.get_default("foo"))
+        self.assertEqual(42, parser.get_default("bar"))
+
+# ==========================
+# Namespace 'contains' tests
+# ==========================
+
+class TestNamespaceContainsSimple(TestCase):
+
+    def test_empty(self):
+        ns = argparse.Namespace()
+        self.assertEqual('' in ns, False)
+        self.assertEqual('' not in ns, True)
+        self.assertEqual('x' in ns, False)
+
+    def test_non_empty(self):
+        ns = argparse.Namespace(x=1, y=2)
+        self.assertEqual('x' in ns, True)
+        self.assertEqual('x' not in ns, False)
+        self.assertEqual('y' in ns, True)
+        self.assertEqual('' in ns, False)
+        self.assertEqual('xx' in ns, False)
+        self.assertEqual('z' in ns, False)
+
+# =====================
+# Help formatting tests
+# =====================
+
+class TestHelpFormattingMetaclass(type):
+
+    def __init__(cls, name, bases, bodydict):
+        if name == 'HelpTestCase':
+            return
+
+        class AddTests(object):
+
+            def __init__(self, test_class, func_suffix, std_name):
+                self.func_suffix = func_suffix
+                self.std_name = std_name
+
+                for test_func in [self.test_format,
+                                  self.test_print,
+                                  self.test_print_file]:
+                    test_name = '%s_%s' % (test_func.__name__, func_suffix)
+
+                    def test_wrapper(self, test_func=test_func):
+                        test_func(self)
+                    try:
+                        test_wrapper.__name__ = test_name
+                    except TypeError:
+                        pass
+                    setattr(test_class, test_name, test_wrapper)
+
+            def _get_parser(self, tester):
+                parser = argparse.ArgumentParser(
+                    *tester.parser_signature.args,
+                    **tester.parser_signature.kwargs)
+                for argument_sig in tester.argument_signatures:
+                    parser.add_argument(*argument_sig.args,
+                                        **argument_sig.kwargs)
+                group_signatures = tester.argument_group_signatures
+                for group_sig, argument_sigs in group_signatures:
+                    group = parser.add_argument_group(*group_sig.args,
+                                                      **group_sig.kwargs)
+                    for argument_sig in argument_sigs:
+                        group.add_argument(*argument_sig.args,
+                                           **argument_sig.kwargs)
+                return parser
+
+            def _test(self, tester, parser_text):
+                expected_text = getattr(tester, self.func_suffix)
+                expected_text = textwrap.dedent(expected_text)
+                if expected_text != parser_text:
+                    print(repr(expected_text))
+                    print(repr(parser_text))
+                    for char1, char2 in zip(expected_text, parser_text):
+                        if char1 != char2:
+                            print('first diff: %r %r' % (char1, char2))
+                            break
+                tester.assertEqual(expected_text, parser_text)
+
+            def test_format(self, tester):
+                parser = self._get_parser(tester)
+                format = getattr(parser, 'format_%s' % self.func_suffix)
+                self._test(tester, format())
+
+            def test_print(self, tester):
+                parser = self._get_parser(tester)
+                print_ = getattr(parser, 'print_%s' % self.func_suffix)
+                old_stream = getattr(sys, self.std_name)
+                setattr(sys, self.std_name, StdIOBuffer())
+                try:
+                    print_()
+                    parser_text = getattr(sys, self.std_name).getvalue()
+                finally:
+                    setattr(sys, self.std_name, old_stream)
+                self._test(tester, parser_text)
+
+            def test_print_file(self, tester):
+                parser = self._get_parser(tester)
+                print_ = getattr(parser, 'print_%s' % self.func_suffix)
+                sfile = StdIOBuffer()
+                print_(sfile)
+                parser_text = sfile.getvalue()
+                self._test(tester, parser_text)
+
+        # add tests for {format,print}_{usage,help,version}
+        for func_suffix, std_name in [('usage', 'stdout'),
+                                      ('help', 'stdout'),
+                                      ('version', 'stderr')]:
+            AddTests(cls, func_suffix, std_name)
+
+bases = TestCase,
+HelpTestCase = TestHelpFormattingMetaclass('HelpTestCase', bases, {})
+
+
+class TestHelpBiggerOptionals(HelpTestCase):
+    """Make sure that argument help aligns when options are longer"""
+
+    parser_signature = Sig(prog='PROG', description='DESCRIPTION',
+                           epilog='EPILOG', version='0.1')
+    argument_signatures = [
+        Sig('-x', action='store_true', help='X HELP'),
+        Sig('--y', help='Y HELP'),
+        Sig('foo', help='FOO HELP'),
+        Sig('bar', help='BAR HELP'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-v] [-x] [--y Y] foo bar
+        '''
+    help = usage + '''\
+
+        DESCRIPTION
+
+        positional arguments:
+          foo            FOO HELP
+          bar            BAR HELP
+
+        optional arguments:
+          -h, --help     show this help message and exit
+          -v, --version  show program's version number and exit
+          -x             X HELP
+          --y Y          Y HELP
+
+        EPILOG
+    '''
+    version = '''\
+        0.1
+        '''
+
+
+class TestHelpBiggerOptionalGroups(HelpTestCase):
+    """Make sure that argument help aligns when options are longer"""
+
+    parser_signature = Sig(prog='PROG', description='DESCRIPTION',
+                           epilog='EPILOG', version='0.1')
+    argument_signatures = [
+        Sig('-x', action='store_true', help='X HELP'),
+        Sig('--y', help='Y HELP'),
+        Sig('foo', help='FOO HELP'),
+        Sig('bar', help='BAR HELP'),
+    ]
+    argument_group_signatures = [
+        (Sig('GROUP TITLE', description='GROUP DESCRIPTION'), [
+            Sig('baz', help='BAZ HELP'),
+            Sig('-z', nargs='+', help='Z HELP')]),
+    ]
+    usage = '''\
+        usage: PROG [-h] [-v] [-x] [--y Y] [-z Z [Z ...]] foo bar baz
+        '''
+    help = usage + '''\
+
+        DESCRIPTION
+
+        positional arguments:
+          foo            FOO HELP
+          bar            BAR HELP
+
+        optional arguments:
+          -h, --help     show this help message and exit
+          -v, --version  show program's version number and exit
+          -x             X HELP
+          --y Y          Y HELP
+
+        GROUP TITLE:
+          GROUP DESCRIPTION
+
+          baz            BAZ HELP
+          -z Z [Z ...]   Z HELP
+
+        EPILOG
+    '''
+    version = '''\
+        0.1
+        '''
+
+
+class TestHelpBiggerPositionals(HelpTestCase):
+    """Make sure that help aligns when arguments are longer"""
+
+    parser_signature = Sig(usage='USAGE', description='DESCRIPTION')
+    argument_signatures = [
+        Sig('-x', action='store_true', help='X HELP'),
+        Sig('--y', help='Y HELP'),
+        Sig('ekiekiekifekang', help='EKI HELP'),
+        Sig('bar', help='BAR HELP'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: USAGE
+        '''
+    help = usage + '''\
+
+        DESCRIPTION
+
+        positional arguments:
+          ekiekiekifekang  EKI HELP
+          bar              BAR HELP
+
+        optional arguments:
+          -h, --help       show this help message and exit
+          -x               X HELP
+          --y Y            Y HELP
+        '''
+
+    version = ''
+
+
+class TestHelpReformatting(HelpTestCase):
+    """Make sure that text after short names starts on the first line"""
+
+    parser_signature = Sig(
+        prog='PROG',
+        description='   oddly    formatted\n'
+                    'description\n'
+                    '\n'
+                    'that is so long that it should go onto multiple '
+                    'lines when wrapped')
+    argument_signatures = [
+        Sig('-x', metavar='XX', help='oddly\n'
+                                     '    formatted -x help'),
+        Sig('y', metavar='yyy', help='normal y help'),
+    ]
+    argument_group_signatures = [
+        (Sig('title', description='\n'
+                                  '    oddly formatted group\n'
+                                  '\n'
+                                  'description'),
+         [Sig('-a', action='store_true',
+              help=' oddly \n'
+                   'formatted    -a  help  \n'
+                   '    again, so long that it should be wrapped over '
+                   'multiple lines')]),
+    ]
+    usage = '''\
+        usage: PROG [-h] [-x XX] [-a] yyy
+        '''
+    help = usage + '''\
+
+        oddly formatted description that is so long that it should go onto \
+multiple
+        lines when wrapped
+
+        positional arguments:
+          yyy         normal y help
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          -x XX       oddly formatted -x help
+
+        title:
+          oddly formatted group description
+
+          -a          oddly formatted -a help again, so long that it should \
+be wrapped
+                      over multiple lines
+        '''
+    version = ''
+
+
+class TestHelpWrappingShortNames(HelpTestCase):
+    """Make sure that text after short names starts on the first line"""
+
+    parser_signature = Sig(prog='PROG', description= 'D\nD' * 30)
+    argument_signatures = [
+        Sig('-x', metavar='XX', help='XHH HX' * 20),
+        Sig('y', metavar='yyy', help='YH YH' * 20),
+    ]
+    argument_group_signatures = [
+        (Sig('ALPHAS'), [
+            Sig('-a', action='store_true', help='AHHH HHA' * 10)]),
+    ]
+    usage = '''\
+        usage: PROG [-h] [-x XX] [-a] yyy
+        '''
+    help = usage + '''\
+
+        D DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD \
+DD DD DD
+        DD DD DD DD D
+
+        positional arguments:
+          yyy         YH YHYH YHYH YHYH YHYH YHYH YHYH YHYH YHYH YHYH YHYH \
+YHYH YHYH
+                      YHYH YHYH YHYH YHYH YHYH YHYH YHYH YH
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          -x XX       XHH HXXHH HXXHH HXXHH HXXHH HXXHH HXXHH HXXHH HXXHH \
+HXXHH HXXHH
+                      HXXHH HXXHH HXXHH HXXHH HXXHH HXXHH HXXHH HXXHH HXXHH HX
+
+        ALPHAS:
+          -a          AHHH HHAAHHH HHAAHHH HHAAHHH HHAAHHH HHAAHHH HHAAHHH \
+HHAAHHH
+                      HHAAHHH HHAAHHH HHA
+        '''
+    version = ''
+
+
+class TestHelpWrappingLongNames(HelpTestCase):
+    """Make sure that text after long names starts on the next line"""
+
+    parser_signature = Sig(usage='USAGE', description= 'D D' * 30,
+                           version='V V'*30)
+    argument_signatures = [
+        Sig('-x', metavar='X' * 25, help='XH XH' * 20),
+        Sig('y', metavar='y' * 25, help='YH YH' * 20),
+    ]
+    argument_group_signatures = [
+        (Sig('ALPHAS'), [
+            Sig('-a', metavar='A' * 25, help='AH AH' * 20),
+            Sig('z', metavar='z' * 25, help='ZH ZH' * 20)]),
+    ]
+    usage = '''\
+        usage: USAGE
+        '''
+    help = usage + '''\
+
+        D DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD DD \
+DD DD DD
+        DD DD DD DD D
+
+        positional arguments:
+          yyyyyyyyyyyyyyyyyyyyyyyyy
+                                YH YHYH YHYH YHYH YHYH YHYH YHYH YHYH YHYH \
+YHYH YHYH
+                                YHYH YHYH YHYH YHYH YHYH YHYH YHYH YHYH YHYH YH
+
+        optional arguments:
+          -h, --help            show this help message and exit
+          -v, --version         show program's version number and exit
+          -x XXXXXXXXXXXXXXXXXXXXXXXXX
+                                XH XHXH XHXH XHXH XHXH XHXH XHXH XHXH XHXH \
+XHXH XHXH
+                                XHXH XHXH XHXH XHXH XHXH XHXH XHXH XHXH XHXH XH
+
+        ALPHAS:
+          -a AAAAAAAAAAAAAAAAAAAAAAAAA
+                                AH AHAH AHAH AHAH AHAH AHAH AHAH AHAH AHAH \
+AHAH AHAH
+                                AHAH AHAH AHAH AHAH AHAH AHAH AHAH AHAH AHAH AH
+          zzzzzzzzzzzzzzzzzzzzzzzzz
+                                ZH ZHZH ZHZH ZHZH ZHZH ZHZH ZHZH ZHZH ZHZH \
+ZHZH ZHZH
+                                ZHZH ZHZH ZHZH ZHZH ZHZH ZHZH ZHZH ZHZH ZHZH ZH
+        '''
+    version = '''\
+        V VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV VV \
+VV VV VV
+        VV VV VV VV V
+        '''
+
+
+class TestHelpUsage(HelpTestCase):
+    """Test basic usage messages"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('-w', nargs='+', help='w'),
+        Sig('-x', nargs='*', help='x'),
+        Sig('a', help='a'),
+        Sig('b', help='b', nargs=2),
+        Sig('c', help='c', nargs='?'),
+    ]
+    argument_group_signatures = [
+        (Sig('group'), [
+            Sig('-y', nargs='?', help='y'),
+            Sig('-z', nargs=3, help='z'),
+            Sig('d', help='d', nargs='*'),
+            Sig('e', help='e', nargs='+'),
+        ])
+    ]
+    usage = '''\
+        usage: PROG [-h] [-w W [W ...]] [-x [X [X ...]]] [-y [Y]] [-z Z Z Z]
+                    a b b [c] [d [d ...]] e [e ...]
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          a               a
+          b               b
+          c               c
+
+        optional arguments:
+          -h, --help      show this help message and exit
+          -w W [W ...]    w
+          -x [X [X ...]]  x
+
+        group:
+          -y [Y]          y
+          -z Z Z Z        z
+          d               d
+          e               e
+        '''
+    version = ''
+
+
+class TestHelpOnlyUserGroups(HelpTestCase):
+    """Test basic usage messages"""
+
+    parser_signature = Sig(prog='PROG', add_help=False)
+    argument_signatures = []
+    argument_group_signatures = [
+        (Sig('xxxx'), [
+            Sig('-x', help='x'),
+            Sig('a', help='a'),
+        ]),
+        (Sig('yyyy'), [
+            Sig('b', help='b'),
+            Sig('-y', help='y'),
+        ]),
+    ]
+    usage = '''\
+        usage: PROG [-x X] [-y Y] a b
+        '''
+    help = usage + '''\
+
+        xxxx:
+          -x X  x
+          a     a
+
+        yyyy:
+          b     b
+          -y Y  y
+        '''
+    version = ''
+
+
+class TestHelpUsageLongProg(HelpTestCase):
+    """Test usage messages where the prog is long"""
+
+    parser_signature = Sig(prog='P' * 60)
+    argument_signatures = [
+        Sig('-w', metavar='W'),
+        Sig('-x', metavar='X'),
+        Sig('a'),
+        Sig('b'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
+               [-h] [-w W] [-x X] a b
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          a
+          b
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          -w W
+          -x X
+        '''
+    version = ''
+
+
+class TestHelpUsageLongProgOptionsWrap(HelpTestCase):
+    """Test usage messages where the prog is long and the optionals wrap"""
+
+    parser_signature = Sig(prog='P' * 60)
+    argument_signatures = [
+        Sig('-w', metavar='W' * 25),
+        Sig('-x', metavar='X' * 25),
+        Sig('-y', metavar='Y' * 25),
+        Sig('-z', metavar='Z' * 25),
+        Sig('a'),
+        Sig('b'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
+               [-h] [-w WWWWWWWWWWWWWWWWWWWWWWWWW] \
+[-x XXXXXXXXXXXXXXXXXXXXXXXXX]
+               [-y YYYYYYYYYYYYYYYYYYYYYYYYY] [-z ZZZZZZZZZZZZZZZZZZZZZZZZZ]
+               a b
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          a
+          b
+
+        optional arguments:
+          -h, --help            show this help message and exit
+          -w WWWWWWWWWWWWWWWWWWWWWWWWW
+          -x XXXXXXXXXXXXXXXXXXXXXXXXX
+          -y YYYYYYYYYYYYYYYYYYYYYYYYY
+          -z ZZZZZZZZZZZZZZZZZZZZZZZZZ
+        '''
+    version = ''
+
+
+class TestHelpUsageLongProgPositionalsWrap(HelpTestCase):
+    """Test usage messages where the prog is long and the positionals wrap"""
+
+    parser_signature = Sig(prog='P' * 60, add_help=False)
+    argument_signatures = [
+        Sig('a' * 25),
+        Sig('b' * 25),
+        Sig('c' * 25),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
+               aaaaaaaaaaaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbb
+               ccccccccccccccccccccccccc
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          aaaaaaaaaaaaaaaaaaaaaaaaa
+          bbbbbbbbbbbbbbbbbbbbbbbbb
+          ccccccccccccccccccccccccc
+        '''
+    version = ''
+
+
+class TestHelpUsageOptionalsWrap(HelpTestCase):
+    """Test usage messages where the optionals wrap"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('-w', metavar='W' * 25),
+        Sig('-x', metavar='X' * 25),
+        Sig('-y', metavar='Y' * 25),
+        Sig('-z', metavar='Z' * 25),
+        Sig('a'),
+        Sig('b'),
+        Sig('c'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-w WWWWWWWWWWWWWWWWWWWWWWWWW] \
+[-x XXXXXXXXXXXXXXXXXXXXXXXXX]
+                    [-y YYYYYYYYYYYYYYYYYYYYYYYYY] \
+[-z ZZZZZZZZZZZZZZZZZZZZZZZZZ]
+                    a b c
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          a
+          b
+          c
+
+        optional arguments:
+          -h, --help            show this help message and exit
+          -w WWWWWWWWWWWWWWWWWWWWWWWWW
+          -x XXXXXXXXXXXXXXXXXXXXXXXXX
+          -y YYYYYYYYYYYYYYYYYYYYYYYYY
+          -z ZZZZZZZZZZZZZZZZZZZZZZZZZ
+        '''
+    version = ''
+
+
+class TestHelpUsagePositionalsWrap(HelpTestCase):
+    """Test usage messages where the positionals wrap"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('-x'),
+        Sig('-y'),
+        Sig('-z'),
+        Sig('a' * 25),
+        Sig('b' * 25),
+        Sig('c' * 25),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-x X] [-y Y] [-z Z]
+                    aaaaaaaaaaaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbb
+                    ccccccccccccccccccccccccc
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          aaaaaaaaaaaaaaaaaaaaaaaaa
+          bbbbbbbbbbbbbbbbbbbbbbbbb
+          ccccccccccccccccccccccccc
+
+        optional arguments:
+          -h, --help            show this help message and exit
+          -x X
+          -y Y
+          -z Z
+        '''
+    version = ''
+
+
+class TestHelpUsageOptionalsPositionalsWrap(HelpTestCase):
+    """Test usage messages where the optionals and positionals wrap"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('-x', metavar='X' * 25),
+        Sig('-y', metavar='Y' * 25),
+        Sig('-z', metavar='Z' * 25),
+        Sig('a' * 25),
+        Sig('b' * 25),
+        Sig('c' * 25),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-x XXXXXXXXXXXXXXXXXXXXXXXXX] \
+[-y YYYYYYYYYYYYYYYYYYYYYYYYY]
+                    [-z ZZZZZZZZZZZZZZZZZZZZZZZZZ]
+                    aaaaaaaaaaaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbb
+                    ccccccccccccccccccccccccc
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          aaaaaaaaaaaaaaaaaaaaaaaaa
+          bbbbbbbbbbbbbbbbbbbbbbbbb
+          ccccccccccccccccccccccccc
+
+        optional arguments:
+          -h, --help            show this help message and exit
+          -x XXXXXXXXXXXXXXXXXXXXXXXXX
+          -y YYYYYYYYYYYYYYYYYYYYYYYYY
+          -z ZZZZZZZZZZZZZZZZZZZZZZZZZ
+        '''
+    version = ''
+
+
+class TestHelpUsageOptionalsOnlyWrap(HelpTestCase):
+    """Test usage messages where there are only optionals and they wrap"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('-x', metavar='X' * 25),
+        Sig('-y', metavar='Y' * 25),
+        Sig('-z', metavar='Z' * 25),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-x XXXXXXXXXXXXXXXXXXXXXXXXX] \
+[-y YYYYYYYYYYYYYYYYYYYYYYYYY]
+                    [-z ZZZZZZZZZZZZZZZZZZZZZZZZZ]
+        '''
+    help = usage + '''\
+
+        optional arguments:
+          -h, --help            show this help message and exit
+          -x XXXXXXXXXXXXXXXXXXXXXXXXX
+          -y YYYYYYYYYYYYYYYYYYYYYYYYY
+          -z ZZZZZZZZZZZZZZZZZZZZZZZZZ
+        '''
+    version = ''
+
+
+class TestHelpUsagePositionalsOnlyWrap(HelpTestCase):
+    """Test usage messages where there are only positionals and they wrap"""
+
+    parser_signature = Sig(prog='PROG', add_help=False)
+    argument_signatures = [
+        Sig('a' * 25),
+        Sig('b' * 25),
+        Sig('c' * 25),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG aaaaaaaaaaaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbb
+                    ccccccccccccccccccccccccc
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          aaaaaaaaaaaaaaaaaaaaaaaaa
+          bbbbbbbbbbbbbbbbbbbbbbbbb
+          ccccccccccccccccccccccccc
+        '''
+    version = ''
+
+
+class TestHelpVariableExpansion(HelpTestCase):
+    """Test that variables are expanded properly in help messages"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('-x', type=int,
+            help='x %(prog)s %(default)s %(type)s %%'),
+        Sig('-y', action='store_const', default=42, const='XXX',
+            help='y %(prog)s %(default)s %(const)s'),
+        Sig('--foo', choices='abc',
+            help='foo %(prog)s %(default)s %(choices)s'),
+        Sig('--bar', default='baz', choices=[1, 2], metavar='BBB',
+            help='bar %(prog)s %(default)s %(dest)s'),
+        Sig('spam', help='spam %(prog)s %(default)s'),
+        Sig('badger', default=0.5, help='badger %(prog)s %(default)s'),
+    ]
+    argument_group_signatures = [
+        (Sig('group'), [
+            Sig('-a', help='a %(prog)s %(default)s'),
+            Sig('-b', default=-1, help='b %(prog)s %(default)s'),
+        ])
+    ]
+    usage = ('''\
+        usage: PROG [-h] [-x X] [-y] [--foo {a,b,c}] [--bar BBB] [-a A] [-b B]
+                    spam badger
+        ''')
+    help = usage + '''\
+
+        positional arguments:
+          spam           spam PROG None
+          badger         badger PROG 0.5
+
+        optional arguments:
+          -h, --help     show this help message and exit
+          -x X           x PROG None int %
+          -y             y PROG 42 XXX
+          --foo {a,b,c}  foo PROG None a, b, c
+          --bar BBB      bar PROG baz bar
+
+        group:
+          -a A           a PROG None
+          -b B           b PROG -1
+        '''
+    version = ''
+
+
+class TestHelpVariableExpansionUsageSupplied(HelpTestCase):
+    """Test that variables are expanded properly when usage= is present"""
+
+    parser_signature = Sig(prog='PROG', usage='%(prog)s FOO')
+    argument_signatures = []
+    argument_group_signatures = []
+    usage = ('''\
+        usage: PROG FOO
+        ''')
+    help = usage + '''\
+
+        optional arguments:
+          -h, --help  show this help message and exit
+        '''
+    version = ''
+
+
+class TestHelpVariableExpansionNoArguments(HelpTestCase):
+    """Test that variables are expanded properly with no arguments"""
+
+    parser_signature = Sig(prog='PROG', add_help=False)
+    argument_signatures = []
+    argument_group_signatures = []
+    usage = ('''\
+        usage: PROG
+        ''')
+    help = usage
+    version = ''
+
+
+class TestHelpSuppressUsage(HelpTestCase):
+    """Test that items can be suppressed in usage messages"""
+
+    parser_signature = Sig(prog='PROG', usage=argparse.SUPPRESS)
+    argument_signatures = [
+        Sig('--foo', help='foo help'),
+        Sig('spam', help='spam help'),
+    ]
+    argument_group_signatures = []
+    help = '''\
+        positional arguments:
+          spam        spam help
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO   foo help
+        '''
+    usage = ''
+    version = ''
+
+
+class TestHelpSuppressOptional(HelpTestCase):
+    """Test that optional arguments can be suppressed in help messages"""
+
+    parser_signature = Sig(prog='PROG', add_help=False)
+    argument_signatures = [
+        Sig('--foo', help=argparse.SUPPRESS),
+        Sig('spam', help='spam help'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG spam
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          spam  spam help
+        '''
+    version = ''
+
+
+class TestHelpSuppressOptionalGroup(HelpTestCase):
+    """Test that optional groups can be suppressed in help messages"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('--foo', help='foo help'),
+        Sig('spam', help='spam help'),
+    ]
+    argument_group_signatures = [
+        (Sig('group'), [Sig('--bar', help=argparse.SUPPRESS)]),
+    ]
+    usage = '''\
+        usage: PROG [-h] [--foo FOO] spam
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          spam        spam help
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO   foo help
+        '''
+    version = ''
+
+
+class TestHelpSuppressPositional(HelpTestCase):
+    """Test that positional arguments can be suppressed in help messages"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('--foo', help='foo help'),
+        Sig('spam', help=argparse.SUPPRESS),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [--foo FOO]
+        '''
+    help = usage + '''\
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO   foo help
+        '''
+    version = ''
+
+
+class TestHelpRequiredOptional(HelpTestCase):
+    """Test that required options don't look optional"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('--foo', required=True, help='foo help'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] --foo FOO
+        '''
+    help = usage + '''\
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO   foo help
+        '''
+    version = ''
+
+
+class TestHelpAlternatePrefixChars(HelpTestCase):
+    """Test that options display with different prefix characters"""
+
+    parser_signature = Sig(prog='PROG', prefix_chars='^;', add_help=False)
+    argument_signatures = [
+        Sig('^^foo', action='store_true', help='foo help'),
+        Sig(';b', ';;bar', help='bar help'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [^^foo] [;b BAR]
+        '''
+    help = usage + '''\
+
+        optional arguments:
+          ^^foo              foo help
+          ;b BAR, ;;bar BAR  bar help
+        '''
+    version = ''
+
+
+class TestHelpNoHelpOptional(HelpTestCase):
+    """Test that the --help argument can be suppressed help messages"""
+
+    parser_signature = Sig(prog='PROG', add_help=False)
+    argument_signatures = [
+        Sig('--foo', help='foo help'),
+        Sig('spam', help='spam help'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [--foo FOO] spam
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          spam       spam help
+
+        optional arguments:
+          --foo FOO  foo help
+        '''
+    version = ''
+
+
+class TestHelpVersionOptional(HelpTestCase):
+    """Test that the --version argument can be suppressed help messages"""
+
+    parser_signature = Sig(prog='PROG', version='1.0')
+    argument_signatures = [
+        Sig('--foo', help='foo help'),
+        Sig('spam', help='spam help'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-v] [--foo FOO] spam
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          spam           spam help
+
+        optional arguments:
+          -h, --help     show this help message and exit
+          -v, --version  show program's version number and exit
+          --foo FOO      foo help
+        '''
+    version = '''\
+        1.0
+        '''
+
+
+class TestHelpNone(HelpTestCase):
+    """Test that no errors occur if no help is specified"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('--foo'),
+        Sig('spam'),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [--foo FOO] spam
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          spam
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO
+        '''
+    version = ''
+
+
+class TestHelpTupleMetavar(HelpTestCase):
+    """Test specifying metavar as a tuple"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('-w', help='w', nargs='+', metavar=('W1', 'W2')),
+        Sig('-x', help='x', nargs='*', metavar=('X1', 'X2')),
+        Sig('-y', help='y', nargs=3, metavar=('Y1', 'Y2', 'Y3')),
+        Sig('-z', help='z', nargs='?', metavar=('Z1', )),
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-w W1 [W2 ...]] [-x [X1 [X2 ...]]] [-y Y1 Y2 Y3] \
+[-z [Z1]]
+        '''
+    help = usage + '''\
+
+        optional arguments:
+          -h, --help        show this help message and exit
+          -w W1 [W2 ...]    w
+          -x [X1 [X2 ...]]  x
+          -y Y1 Y2 Y3       y
+          -z [Z1]           z
+        '''
+    version = ''
+
+
+class TestHelpRawText(HelpTestCase):
+    """Test the RawTextHelpFormatter"""
+
+    parser_signature = Sig(
+        prog='PROG', formatter_class=argparse.RawTextHelpFormatter,
+        description='Keep the formatting\n'
+                    '    exactly as it is written\n'
+                    '\n'
+                    'here\n')
+
+    argument_signatures = [
+        Sig('--foo', help='    foo help should also\n'
+                          'appear as given here'),
+        Sig('spam', help='spam help'),
+    ]
+    argument_group_signatures = [
+        (Sig('title', description='    This text\n'
+                                  '  should be indented\n'
+                                  '    exactly like it is here\n'),
+         [Sig('--bar', help='bar help')]),
+    ]
+    usage = '''\
+        usage: PROG [-h] [--foo FOO] [--bar BAR] spam
+        '''
+    help = usage + '''\
+
+        Keep the formatting
+            exactly as it is written
+
+        here
+
+        positional arguments:
+          spam        spam help
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO       foo help should also
+                      appear as given here
+
+        title:
+              This text
+            should be indented
+              exactly like it is here
+
+          --bar BAR   bar help
+        '''
+    version = ''
+
+
+class TestHelpRawDescription(HelpTestCase):
+    """Test the RawTextHelpFormatter"""
+
+    parser_signature = Sig(
+        prog='PROG', formatter_class=argparse.RawDescriptionHelpFormatter,
+        description='Keep the formatting\n'
+                    '    exactly as it is written\n'
+                    '\n'
+                    'here\n')
+
+    argument_signatures = [
+        Sig('--foo', help='  foo help should not\n'
+                          '    retain this odd formatting'),
+        Sig('spam', help='spam help'),
+    ]
+    argument_group_signatures = [
+        (Sig('title', description='    This text\n'
+                                  '  should be indented\n'
+                                  '    exactly like it is here\n'),
+         [Sig('--bar', help='bar help')]),
+    ]
+    usage = '''\
+        usage: PROG [-h] [--foo FOO] [--bar BAR] spam
+        '''
+    help = usage + '''\
+
+        Keep the formatting
+            exactly as it is written
+
+        here
+
+        positional arguments:
+          spam        spam help
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO   foo help should not retain this odd formatting
+
+        title:
+              This text
+            should be indented
+              exactly like it is here
+
+          --bar BAR   bar help
+        '''
+    version = ''
+
+
+class TestHelpArgumentDefaults(HelpTestCase):
+    """Test the ArgumentDefaultsHelpFormatter"""
+
+    parser_signature = Sig(
+        prog='PROG', formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+        description='description')
+
+    argument_signatures = [
+        Sig('--foo', help='foo help - oh and by the way, %(default)s'),
+        Sig('--bar', action='store_true', help='bar help'),
+        Sig('spam', help='spam help'),
+        Sig('badger', nargs='?', default='wooden', help='badger help'),
+    ]
+    argument_group_signatures = [
+        (Sig('title', description='description'),
+         [Sig('--baz', type=int, default=42, help='baz help')]),
+    ]
+    usage = '''\
+        usage: PROG [-h] [--foo FOO] [--bar] [--baz BAZ] spam [badger]
+        '''
+    help = usage + '''\
+
+        description
+
+        positional arguments:
+          spam        spam help
+          badger      badger help (default: wooden)
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          --foo FOO   foo help - oh and by the way, None
+          --bar       bar help (default: False)
+
+        title:
+          description
+
+          --baz BAZ   baz help (default: 42)
+        '''
+    version = ''
+
+class TestHelpVersionAction(HelpTestCase):
+    """Test the default help for the version action"""
+
+    parser_signature = Sig(prog='PROG', description='description')
+    argument_signatures = [Sig('-V', '--version', action='version', version='3.6')]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] [-V]
+        '''
+    help = usage + '''\
+
+        description
+
+        optional arguments:
+          -h, --help     show this help message and exit
+          -V, --version  show program's version number and exit
+        '''
+    version = ''
+
+# =====================================
+# Optional/Positional constructor tests
+# =====================================
+
+class TestInvalidArgumentConstructors(TestCase):
+    """Test a bunch of invalid Argument constructors"""
+
+    def assertTypeError(self, *args, **kwargs):
+        parser = argparse.ArgumentParser()
+        self.assertRaises(TypeError, parser.add_argument,
+                          *args, **kwargs)
+
+    def assertValueError(self, *args, **kwargs):
+        parser = argparse.ArgumentParser()
+        self.assertRaises(ValueError, parser.add_argument,
+                          *args, **kwargs)
+
+    def test_invalid_keyword_arguments(self):
+        self.assertTypeError('-x', bar=None)
+        self.assertTypeError('-y', callback='foo')
+        self.assertTypeError('-y', callback_args=())
+        self.assertTypeError('-y', callback_kwargs={})
+
+    def test_missing_destination(self):
+        self.assertTypeError()
+        for action in ['append', 'store']:
+            self.assertTypeError(action=action)
+
+    def test_invalid_option_strings(self):
+        self.assertValueError('--')
+        self.assertValueError('---')
+
+    def test_invalid_type(self):
+        self.assertValueError('--foo', type='int')
+
+    def test_invalid_action(self):
+        self.assertValueError('-x', action='foo')
+        self.assertValueError('foo', action='baz')
+        parser = argparse.ArgumentParser()
+        try:
+            parser.add_argument("--foo", action="store-true")
+        except ValueError:
+            e = sys.exc_info()[1]
+            expected = 'unknown action'
+            msg = 'expected %r, found %r' % (expected, e)
+            self.assertTrue(expected in str(e), msg)
+
+    def test_multiple_dest(self):
+        parser = argparse.ArgumentParser()
+        parser.add_argument(dest='foo')
+        try:
+            parser.add_argument('bar', dest='baz')
+        except ValueError:
+            e = sys.exc_info()[1]
+            expected = 'dest supplied twice for positional argument'
+            msg = 'expected %r, found %r' % (expected, e)
+            self.assertTrue(expected in str(e), msg)
+
+    def test_no_argument_actions(self):
+        for action in ['store_const', 'store_true', 'store_false',
+                       'append_const', 'count']:
+            for attrs in [dict(type=int), dict(nargs='+'),
+                          dict(choices='ab')]:
+                self.assertTypeError('-x', action=action, **attrs)
+
+    def test_no_argument_no_const_actions(self):
+        # options with zero arguments
+        for action in ['store_true', 'store_false', 'count']:
+
+            # const is always disallowed
+            self.assertTypeError('-x', const='foo', action=action)
+
+            # nargs is always disallowed
+            self.assertTypeError('-x', nargs='*', action=action)
+
+    def test_more_than_one_argument_actions(self):
+        for action in ['store', 'append']:
+
+            # nargs=0 is disallowed
+            self.assertValueError('-x', nargs=0, action=action)
+            self.assertValueError('spam', nargs=0, action=action)
+
+            # const is disallowed with non-optional arguments
+            for nargs in [1, '*', '+']:
+                self.assertValueError('-x', const='foo',
+                                      nargs=nargs, action=action)
+                self.assertValueError('spam', const='foo',
+                                      nargs=nargs, action=action)
+
+    def test_required_const_actions(self):
+        for action in ['store_const', 'append_const']:
+
+            # nargs is always disallowed
+            self.assertTypeError('-x', nargs='+', action=action)
+
+    def test_parsers_action_missing_params(self):
+        self.assertTypeError('command', action='parsers')
+        self.assertTypeError('command', action='parsers', prog='PROG')
+        self.assertTypeError('command', action='parsers',
+                             parser_class=argparse.ArgumentParser)
+
+    def test_required_positional(self):
+        self.assertTypeError('foo', required=True)
+
+    def test_user_defined_action(self):
+
+        class Success(Exception):
+            pass
+
+        class Action(object):
+
+            def __init__(self,
+                         option_strings,
+                         dest,
+                         const,
+                         default,
+                         required=False):
+                if dest == 'spam':
+                    if const is Success:
+                        if default is Success:
+                            raise Success()
+
+            def __call__(self, *args, **kwargs):
+                pass
+
+        parser = argparse.ArgumentParser()
+        self.assertRaises(Success, parser.add_argument, '--spam',
+                          action=Action, default=Success, const=Success)
+        self.assertRaises(Success, parser.add_argument, 'spam',
+                          action=Action, default=Success, const=Success)
+
+# ================================
+# Actions returned by add_argument
+# ================================
+
+class TestActionsReturned(TestCase):
+
+    def test_dest(self):
+        parser = argparse.ArgumentParser()
+        action = parser.add_argument('--foo')
+        self.assertEqual(action.dest, 'foo')
+        action = parser.add_argument('-b', '--bar')
+        self.assertEqual(action.dest, 'bar')
+        action = parser.add_argument('-x', '-y')
+        self.assertEqual(action.dest, 'x')
+
+    def test_misc(self):
+        parser = argparse.ArgumentParser()
+        action = parser.add_argument('--foo', nargs='?', const=42,
+                                     default=84, type=int, choices=[1, 2],
+                                     help='FOO', metavar='BAR', dest='baz')
+        self.assertEqual(action.nargs, '?')
+        self.assertEqual(action.const, 42)
+        self.assertEqual(action.default, 84)
+        self.assertEqual(action.type, int)
+        self.assertEqual(action.choices, [1, 2])
+        self.assertEqual(action.help, 'FOO')
+        self.assertEqual(action.metavar, 'BAR')
+        self.assertEqual(action.dest, 'baz')
+
+
+# ================================
+# Argument conflict handling tests
+# ================================
+
+class TestConflictHandling(TestCase):
+
+    def test_bad_type(self):
+        self.assertRaises(ValueError, argparse.ArgumentParser,
+                          conflict_handler='foo')
+
+    def test_conflict_error(self):
+        parser = argparse.ArgumentParser()
+        parser.add_argument('-x')
+        self.assertRaises(argparse.ArgumentError,
+                          parser.add_argument, '-x')
+        parser.add_argument('--spam')
+        self.assertRaises(argparse.ArgumentError,
+                          parser.add_argument, '--spam')
+
+    def test_resolve_error(self):
+        get_parser = argparse.ArgumentParser
+        parser = get_parser(prog='PROG', conflict_handler='resolve')
+
+        parser.add_argument('-x', help='OLD X')
+        parser.add_argument('-x', help='NEW X')
+        self.assertEqual(parser.format_help(), textwrap.dedent('''\
+            usage: PROG [-h] [-x X]
+
+            optional arguments:
+              -h, --help  show this help message and exit
+              -x X        NEW X
+            '''))
+
+        parser.add_argument('--spam', metavar='OLD_SPAM')
+        parser.add_argument('--spam', metavar='NEW_SPAM')
+        self.assertEqual(parser.format_help(), textwrap.dedent('''\
+            usage: PROG [-h] [-x X] [--spam NEW_SPAM]
+
+            optional arguments:
+              -h, --help       show this help message and exit
+              -x X             NEW X
+              --spam NEW_SPAM
+            '''))
+
+
+# =============================
+# Help and Version option tests
+# =============================
+
+class TestOptionalsHelpVersionActions(TestCase):
+    """Test the help and version actions"""
+
+    def _get_error(self, func, *args, **kwargs):
+        try:
+            func(*args, **kwargs)
+        except ArgumentParserError:
+            return sys.exc_info()[1]
+        else:
+            self.assertRaises(ArgumentParserError, func, *args, **kwargs)
+
+    def assertPrintHelpExit(self, parser, args_str):
+        self.assertEqual(
+            parser.format_help(),
+            self._get_error(parser.parse_args, args_str.split()).stdout)
+
+    def assertPrintVersionExit(self, parser, args_str):
+        self.assertEqual(
+            parser.format_version(),
+            self._get_error(parser.parse_args, args_str.split()).stderr)
+
+    def assertArgumentParserError(self, parser, *args):
+        self.assertRaises(ArgumentParserError, parser.parse_args, args)
+
+    def test_version(self):
+        parser = ErrorRaisingArgumentParser(version='1.0')
+        self.assertPrintHelpExit(parser, '-h')
+        self.assertPrintHelpExit(parser, '--help')
+        self.assertPrintVersionExit(parser, '-v')
+        self.assertPrintVersionExit(parser, '--version')
+
+    def test_version_format(self):
+        parser = ErrorRaisingArgumentParser(prog='PPP', version='%(prog)s 3.5')
+        msg = self._get_error(parser.parse_args, ['-v']).stderr
+        self.assertEqual('PPP 3.5\n', msg)
+
+    def test_version_no_help(self):
+        parser = ErrorRaisingArgumentParser(add_help=False, version='1.0')
+        self.assertArgumentParserError(parser, '-h')
+        self.assertArgumentParserError(parser, '--help')
+        self.assertPrintVersionExit(parser, '-v')
+        self.assertPrintVersionExit(parser, '--version')
+
+    def test_version_action(self):
+        parser = ErrorRaisingArgumentParser(prog='XXX')
+        parser.add_argument('-V', action='version', version='%(prog)s 3.7')
+        msg = self._get_error(parser.parse_args, ['-V']).stderr
+        self.assertEqual('XXX 3.7\n', msg)
+
+    def test_no_help(self):
+        parser = ErrorRaisingArgumentParser(add_help=False)
+        self.assertArgumentParserError(parser, '-h')
+        self.assertArgumentParserError(parser, '--help')
+        self.assertArgumentParserError(parser, '-v')
+        self.assertArgumentParserError(parser, '--version')
+
+    def test_alternate_help_version(self):
+        parser = ErrorRaisingArgumentParser()
+        parser.add_argument('-x', action='help')
+        parser.add_argument('-y', action='version')
+        self.assertPrintHelpExit(parser, '-x')
+        self.assertPrintVersionExit(parser, '-y')
+        self.assertArgumentParserError(parser, '-v')
+        self.assertArgumentParserError(parser, '--version')
+
+    def test_help_version_extra_arguments(self):
+        parser = ErrorRaisingArgumentParser(version='1.0')
+        parser.add_argument('-x', action='store_true')
+        parser.add_argument('y')
+
+        # try all combinations of valid prefixes and suffixes
+        valid_prefixes = ['', '-x', 'foo', '-x bar', 'baz -x']
+        valid_suffixes = valid_prefixes + ['--bad-option', 'foo bar baz']
+        for prefix in valid_prefixes:
+            for suffix in valid_suffixes:
+                format = '%s %%s %s' % (prefix, suffix)
+            self.assertPrintHelpExit(parser, format % '-h')
+            self.assertPrintHelpExit(parser, format % '--help')
+            self.assertPrintVersionExit(parser, format % '-v')
+            self.assertPrintVersionExit(parser, format % '--version')
+
+
+# ======================
+# str() and repr() tests
+# ======================
+
+class TestStrings(TestCase):
+    """Test str()  and repr() on Optionals and Positionals"""
+
+    def assertStringEqual(self, obj, result_string):
+        for func in [str, repr]:
+            self.assertEqual(func(obj), result_string)
+
+    def test_optional(self):
+        option = argparse.Action(
+            option_strings=['--foo', '-a', '-b'],
+            dest='b',
+            type='int',
+            nargs='+',
+            default=42,
+            choices=[1, 2, 3],
+            help='HELP',
+            metavar='METAVAR')
+        string = (
+            "Action(option_strings=['--foo', '-a', '-b'], dest='b', "
+            "nargs='+', const=None, default=42, type='int', "
+            "choices=[1, 2, 3], help='HELP', metavar='METAVAR')")
+        self.assertStringEqual(option, string)
+
+    def test_argument(self):
+        argument = argparse.Action(
+            option_strings=[],
+            dest='x',
+            type=float,
+            nargs='?',
+            default=2.5,
+            choices=[0.5, 1.5, 2.5],
+            help='H HH H',
+            metavar='MV MV MV')
+        string = (
+            "Action(option_strings=[], dest='x', nargs='?', "
+            "const=None, default=2.5, type=%r, choices=[0.5, 1.5, 2.5], "
+            "help='H HH H', metavar='MV MV MV')" % float)
+        self.assertStringEqual(argument, string)
+
+    def test_namespace(self):
+        ns = argparse.Namespace(foo=42, bar='spam')
+        string = "Namespace(bar='spam', foo=42)"
+        self.assertStringEqual(ns, string)
+
+    def test_parser(self):
+        parser = argparse.ArgumentParser(prog='PROG')
+        string = (
+            "ArgumentParser(prog='PROG', usage=None, description=None, "
+            "version=None, formatter_class=%r, conflict_handler='error', "
+            "add_help=True)" % argparse.HelpFormatter)
+        self.assertStringEqual(parser, string)
+
+# ===============
+# Namespace tests
+# ===============
+
+class TestNamespace(TestCase):
+
+    def test_constructor(self):
+        ns = argparse.Namespace()
+        self.assertRaises(AttributeError, getattr, ns, 'x')
+
+        ns = argparse.Namespace(a=42, b='spam')
+        self.assertEqual(ns.a, 42)
+        self.assertEqual(ns.b, 'spam')
+
+    def test_equality(self):
+        ns1 = argparse.Namespace(a=1, b=2)
+        ns2 = argparse.Namespace(b=2, a=1)
+        ns3 = argparse.Namespace(a=1)
+        ns4 = argparse.Namespace(b=2)
+
+        self.assertEqual(ns1, ns2)
+        self.assertNotEqual(ns1, ns3)
+        self.assertNotEqual(ns1, ns4)
+        self.assertNotEqual(ns2, ns3)
+        self.assertNotEqual(ns2, ns4)
+        self.assertTrue(ns1 != ns3)
+        self.assertTrue(ns1 != ns4)
+        self.assertTrue(ns2 != ns3)
+        self.assertTrue(ns2 != ns4)
+
+
+# ===================
+# File encoding tests
+# ===================
+
+class TestEncoding(TestCase):
+
+    def _test_module_encoding(self, path):
+        path, _ = os.path.splitext(path)
+        path += ".py"
+        with codecs.open(path, 'r', 'utf8') as f:
+            f.read()
+
+    def test_argparse_module_encoding(self):
+        self._test_module_encoding(argparse.__file__)
+
+    def test_test_argparse_module_encoding(self):
+        self._test_module_encoding(__file__)
+
+# ===================
+# ArgumentError tests
+# ===================
+
+class TestArgumentError(TestCase):
+
+    def test_argument_error(self):
+        msg = "my error here"
+        error = argparse.ArgumentError(None, msg)
+        self.assertEqual(str(error), msg)
+
+# =======================
+# ArgumentTypeError tests
+# =======================
+
+class TestArgumentError(TestCase):
+
+    def test_argument_type_error(self):
+
+        def spam(string):
+            raise argparse.ArgumentTypeError('spam!')
+
+        parser = ErrorRaisingArgumentParser(prog='PROG', add_help=False)
+        parser.add_argument('x', type=spam)
+        try:
+            parser.parse_args(['XXX'])
+        except ArgumentParserError:
+            expected = 'usage: PROG x\nPROG: error: argument x: spam!\n'
+            msg = sys.exc_info()[1].stderr
+            self.assertEqual(expected, msg)
+        else:
+            self.fail()
+
+# ======================
+# parse_known_args tests
+# ======================
+
+class TestParseKnownArgs(TestCase):
+
+    def test_optionals(self):
+        parser = argparse.ArgumentParser()
+        parser.add_argument('--foo')
+        args, extras = parser.parse_known_args('--foo F --bar --baz'.split())
+        self.assertEqual(NS(foo='F'), args)
+        self.assertEqual(['--bar', '--baz'], extras)
+
+    def test_mixed(self):
+        parser = argparse.ArgumentParser()
+        parser.add_argument('-v', nargs='?', const=1, type=int)
+        parser.add_argument('--spam', action='store_false')
+        parser.add_argument('badger')
+
+        argv = ["B", "C", "--foo", "-v", "3", "4"]
+        args, extras = parser.parse_known_args(argv)
+        self.assertEqual(NS(v=3, spam=True, badger="B"), args)
+        self.assertEqual(["C", "--foo", "4"], extras)
+
+# ============================
+# from argparse import * tests
+# ============================
+
+class TestImportStar(TestCase):
+
+    def test(self):
+        for name in argparse.__all__:
+            self.assertTrue(hasattr(argparse, name))
+
+    def test_all_exports_everything_but_modules(self):
+        items = [
+            name
+            for name, value in vars(argparse).items()
+            if not name.startswith("_")
+            if not inspect.ismodule(value)
+        ]
+        self.assertEqual(sorted(items), sorted(argparse.__all__))
+
+def test_main():
+    # silence warnings about version argument - these are expected
+    with test_support.check_warnings(
+            ('The "version" argument to ArgumentParser is deprecated.',
+             DeprecationWarning),
+            ('The (format|print)_version method is deprecated',
+             DeprecationWarning)):
+        test_support.run_unittest(__name__)
+    # Remove global references to avoid looking like we have refleaks.
+    RFile.seen = {}
+    WFile.seen = set()
+
+
+
+if __name__ == '__main__':
+    test_main()