How to use the pycodestyle.register_check function in pycodestyle

def test_register_invalid_check(self):
        class InvalidChecker(DummyChecker):
            def __init__(self, filename):
                pass

        def check_dummy(logical, tokens):
            if False:
                yield
        pycodestyle.register_check(InvalidChecker, ['Z741'])
        pycodestyle.register_check(check_dummy, ['Z441'])

        for checkers in pycodestyle._checks.values():
            self.assertTrue(DummyChecker not in checkers)
            self.assertTrue(check_dummy not in checkers)

        self.assertRaises(TypeError, pycodestyle.register_check)

def test_register_invalid_check(self):
        class InvalidChecker(DummyChecker):
            def __init__(self, filename):
                pass

        def check_dummy(logical, tokens):
            if False:
                yield
        pycodestyle.register_check(InvalidChecker, ['Z741'])
        pycodestyle.register_check(check_dummy, ['Z441'])

        for checkers in pycodestyle._checks.values():
            self.assertTrue(DummyChecker not in checkers)
            self.assertTrue(check_dummy not in checkers)

        self.assertRaises(TypeError, pycodestyle.register_check)

def test_check_nullbytes(self):
        pycodestyle.register_check(DummyChecker, ['Z701'])

        pep8style = pycodestyle.StyleGuide()
        count_errors = pep8style.input_file('stdin', lines=['\x00\n'])

        stdout = sys.stdout.getvalue()
        if 'SyntaxError' in stdout:
            # PyPy 2.2 returns a SyntaxError
            expected = "stdin:1:2: E901 SyntaxError"
        elif 'ValueError' in stdout:
            # Python 3.5.
            expected = "stdin:1:1: E901 ValueError"
        else:
            expected = "stdin:1:1: E901 TypeError"
        self.assertTrue(stdout.startswith(expected),
                        msg='Output %r does not start with %r' %
                        (stdout, expected))

def test_check_unicode(self):
        # Do not crash if lines are Unicode (Python 2.x)
        pycodestyle.register_check(DummyChecker, ['Z701'])
        source = '#\n'
        if hasattr(source, 'decode'):
            source = source.decode('ascii')

        pep8style = pycodestyle.StyleGuide()
        count_errors = pep8style.input_file('stdin', lines=[source])

        self.assertFalse(sys.stdout)
        self.assertFalse(sys.stderr)
        self.assertEqual(count_errors, 0)

def test_register_ast_check(self):
        pycodestyle.register_check(DummyChecker, ['Z701'])

        self.assertTrue(DummyChecker in pycodestyle._checks['tree'])
        codes, args = pycodestyle._checks['tree'][DummyChecker]
        self.assertTrue('Z701' in codes)
        self.assertTrue(args is None)

        options = pycodestyle.StyleGuide().options
        self.assertTrue(any(cls == DummyChecker
                            for name, cls, args in options.ast_checks))

# Copyright 2017 Palantir Technologies, Inc.
import logging
import pycodestyle
from autopep8 import continued_indentation as autopep8_c_i
from pyls import hookimpl, lsp

# Check if autopep8's continued_indentation implementation
# is overriding pycodestyle's and if so, re-register
# the check using pycodestyle's implementation as expected
if autopep8_c_i in pycodestyle._checks['logical_line']:
    del pycodestyle._checks['logical_line'][autopep8_c_i]
    pycodestyle.register_check(pycodestyle.continued_indentation)

log = logging.getLogger(__name__)


@hookimpl
def pyls_lint(config, document):
    settings = config.plugin_settings('pycodestyle')
    log.debug("Got pycodestyle settings: %s", settings)

    opts = {
        'exclude': settings.get('exclude'),
        'filename': settings.get('filename'),
        'hang_closing': settings.get('hangClosing'),
        'ignore': settings.get('ignore'),
        'max_line_length': settings.get('maxLineLength'),
        'select': settings.get('select'),

def _register_extensions():
    """Register all the extensions."""
    extensions = util.OrderedSet()
    extensions.add(('pycodestyle', pep8.__version__))
    parser_hooks = []
    options_hooks = []
    ignored_hooks = []
    try:
        from pkg_resources import iter_entry_points
    except ImportError:
        pass
    else:
        for entry in iter_entry_points('flake8.extension'):
            # Do not verify that the requirements versions are valid
            checker = _load_entry_point(entry, verify_requirements=False)
            pep8.register_check(checker, codes=[entry.name])
            extensions.add((checker.name, checker.version))
            if hasattr(checker, 'add_options'):
                parser_hooks.append(checker.add_options)
            if hasattr(checker, 'parse_options'):
                options_hooks.append(checker.parse_options)
            if getattr(checker, 'off_by_default', False) is True:
                ignored_hooks.append(entry.name)
    return extensions, parser_hooks, options_hooks, ignored_hooks

if (
        indent_next and
        not last_line_begins_with_multiline and
        pycodestyle.expand_indent(line) == indent_level + DEFAULT_INDENT_SIZE
    ):
        pos = (start[0], indent[0] + 4)
        desired_indent = indent_level + 2 * DEFAULT_INDENT_SIZE
        if visual_indent:
            yield (pos, 'E129 {0}'.format(desired_indent))
        else:
            yield (pos, 'E125 {0}'.format(desired_indent))


del pycodestyle._checks['logical_line'][pycodestyle.continued_indentation]
pycodestyle.register_check(continued_indentation)


class FixPEP8(object):

    """Fix invalid code.

    Fixer methods are prefixed "fix_". The _fix_source() method looks for these
    automatically.

    The fixer method can take either one or two arguments (in addition to
    self). The first argument is "result", which is the error information from
    pycodestyle. The second argument, "logical", is required only for
    logical-line fixes.

    The fixer method can return the list of modified lines or None. An empty
    list would mean that no changes were made. None would mean that only the

if previous_logical.startswith('def '):
        if blank_lines and pycodestyle.DOCSTRING_REGEX.match(logical_line):
            yield (0, 'E303 too many blank lines ({0})'.format(blank_lines))
    elif pycodestyle.DOCSTRING_REGEX.match(previous_logical):
        # Missing blank line between class docstring and method declaration.
        if (
            indent_level and
            not blank_lines and
            not blank_before and
            logical_line.startswith(('def ')) and
            '(self' in logical_line
        ):
            yield (0, 'E301 expected 1 blank line, found 0')


pycodestyle.register_check(extended_blank_lines)


def continued_indentation(logical_line, tokens, indent_level, indent_char,
                          noqa):
    """Override pycodestyle's function to provide indentation information."""
    first_row = tokens[0][2][0]
    nrows = 1 + tokens[-1][2][0] - first_row
    if noqa or nrows == 1:
        return

    # indent_next tells us whether the next block is indented. Assuming
    # that it is indented by 4 spaces, then we should not allow 4-space
    # indents on the final continuation line. In turn, some other
    # indents are allowed to have an extra 4 spaces.
    indent_next = logical_line.endswith(':')

if previous_logical.startswith('def '):
        if blank_lines and pycodestyle.DOCSTRING_REGEX.match(logical_line):
            yield (0, 'E303 too many blank lines ({0})'.format(blank_lines))
    elif pycodestyle.DOCSTRING_REGEX.match(previous_logical):
        # Missing blank line between class docstring and method declaration.
        if (
            indent_level and
            not blank_lines and
            not blank_before and
            logical_line.startswith(('def ')) and
            '(self' in logical_line
        ):
            yield (0, 'E301 expected 1 blank line, found 0')


pycodestyle.register_check(extended_blank_lines)


def continued_indentation(logical_line, tokens, indent_level, indent_char,
                          noqa):
    """Override pycodestyle's function to provide indentation information."""
    first_row = tokens[0][2][0]
    nrows = 1 + tokens[-1][2][0] - first_row
    if noqa or nrows == 1:
        return

    # indent_next tells us whether the next block is indented. Assuming
    # that it is indented by 4 spaces, then we should not allow 4-space
    # indents on the final continuation line. In turn, some other
    # indents are allowed to have an extra 4 spaces.
    indent_next = logical_line.endswith(':')