remove vcs integration

13 files changed, 2 insertions, 659 deletions

diff --git a/docs/source/internal/writing-code.rst b/docs/source/internal/writing-code.rst
index 9d260b7..d8c63fe 100644
--- a/docs/source/internal/writing-code.rst
+++ b/docs/source/internal/writing-code.rst
@@ -59,7 +59,6 @@ accepts as well as what it returns.
             filepaths = list(copy_indexed_files_to(tempdir, lazy))
             app.initialize(['.'])
             app.options.exclude = update_excludes(app.options.exclude, tempdir)
-            app.options._running_from_vcs = True
             app.run_checks(filepaths)
 
         app.report_errors()
diff --git a/docs/source/manpage.rst b/docs/source/manpage.rst
index 9c002b9..826ec8b 100644
--- a/docs/source/manpage.rst
+++ b/docs/source/manpage.rst
@@ -70,9 +70,6 @@ All options available as of Flake8 3.1.0::
                           Enable plugins and extensions that are otherwise
                           disabled by default
     --exit-zero           Exit with status code "0" even if there are errors.
-    --install-hook=INSTALL_HOOK
-                          Install a hook that is run prior to a commit for the
-                          supported version control system.
     -j JOBS, --jobs=JOBS  Number of subprocesses to use to run checks in
                           parallel. This is ignored on Windows. The default,
                           "auto", will auto-detect the number of processors
diff --git a/docs/source/user/options.rst b/docs/source/user/options.rst
index d2c0edb..885bb02 100644
--- a/docs/source/user/options.rst
+++ b/docs/source/user/options.rst
@@ -78,8 +78,6 @@ Index of Options
 
 - :option:`flake8 --exit-zero`
 
-- :option:`flake8 --install-hook`
-
 - :option:`flake8 --jobs`
 
 - :option:`flake8 --output-file`
@@ -751,28 +749,6 @@ Options and their Descriptions
     This **can not** be specified in config files.
 
 
-.. option:: --install-hook=VERSION_CONTROL_SYSTEM
-
-    :ref:`Go back to index <top>`
-
-    Install a hook for your version control system that is executed before
-    or during commit.
-
-    The available options are:
-
-    - git
-    - mercurial
-
-    Command-line usage:
-
-    .. prompt:: bash
-
-        flake8 --install-hook=git
-        flake8 --install-hook=mercurial
-
-    This **can not** be specified in config files.
-
-
 .. option:: --jobs=<n>
 
     :ref:`Go back to index <top>`
diff --git a/docs/source/user/using-hooks.rst b/docs/source/user/using-hooks.rst
index d156ad0..d8af5f8 100644
--- a/docs/source/user/using-hooks.rst
+++ b/docs/source/user/using-hooks.rst
@@ -36,83 +36,7 @@ plugins, use the ``additional_dependencies`` setting.
         -   id: flake8
             additional_dependencies: [flake8-docstrings]
 
-
-Built-in Hook Integration
-=========================
-
-.. note::
-
-    It is strongly suggested to use |Flake8| via `pre-commit`_ over the
-    built-in hook mechanisms.  ``pre-commit`` smooths out many of the rough
-    edges of ``git`` and is much more battle-tested than the |Flake8|
-    hook implementation.
-
-|Flake8| can be integrated into your development workflow in many ways. A
-default installation of |Flake8| can install pre-commit hooks for both
-`Git`_ and `Mercurial`_. To install a built-in hook, you can use the
-:option:`flake8 --install-hook` command-line option. For example, you can
-install a git pre-commit hook by running:
-
-.. prompt:: bash
-
-    flake8 --install-hook git
-
-This will install the pre-commit hook into ``.git/hooks/``. Alternatively,
-you can install the mercurial commit hook by running
-
-.. prompt:: bash
-
-    flake8 --install-hook mercurial
-
-
-Preventing Commits
-==================
-
-By default, |Flake8| does not prevent you from creating a commit with these
-hooks. Both hooks can be configured to be strict easily.
-
-Both our Git and Mercurial hooks check for the presence of ``flake8.strict``
-in each VCS' config. For example, you might configure this like so:
-
-.. prompt:: bash
-
-    git config --bool flake8.strict true
-    hg config flake8.strict true
-
-
-Checking All Modified Files Currently Tracked
-=============================================
-
-.. note::
-
-    Mercurial does not have the concept of an index or "stage" as best as I
-    understand.
-
-|Flake8| aims to make smart choices that keep things fast for users where
-possible. As a result, the |Flake8| Git pre-commit will default to only
-checking files that have been staged (i.e., added to the index). If, however,
-you are keen to be lazy and not independently add files to your git index, you
-can set ``flake8.lazy`` to ``true`` (similar to how you would set
-``flake8.strict`` above) and this will check all tracked files.
-
-This is to support users who often find themselves doing things like:
-
-.. prompt:: bash
-
-    git commit -a
-
-.. note::
-
-    If you have files you have not yet added to the index, |Flake8| will not
-    see these and will not check them for you. You must ``git-add`` them
-    first.
-
-
 .. _pre-commit:
     https://pre-commit.com/
 .. _pre-commit docs:
     https://pre-commit.com/#pre-commit-configyaml---hooks
-.. _Git:
-    https://git-scm.com/
-.. _Mercurial:
-    https://www.mercurial-scm.org/
diff --git a/src/flake8/checker.py b/src/flake8/checker.py
index b4ef97d..224bf64 100644
--- a/src/flake8/checker.py
+++ b/src/flake8/checker.py
@@ -200,7 +200,6 @@ class Manager(object):
             paths = ["."]
 
         filename_patterns = self.options.filename
-        running_from_vcs = self.options._running_from_vcs
         running_from_diff = self.options.diff
 
         # NOTE(sigmavirus24): Yes this is a little unsightly, but it's our
@@ -218,10 +217,8 @@ class Manager(object):
             # the event that the argument and the filename are identical.
             # If it was specified explicitly, the user intended for it to be
             # checked.
-            explicitly_provided = (
-                not running_from_vcs
-                and not running_from_diff
-                and (argument == filename)
+            explicitly_provided = not running_from_diff and (
+                argument == filename
             )
             return (
                 explicitly_provided or matches_filename_patterns
diff --git a/src/flake8/exceptions.py b/src/flake8/exceptions.py
index bef6f4b..ea9bc98 100644
--- a/src/flake8/exceptions.py
+++ b/src/flake8/exceptions.py
@@ -93,51 +93,3 @@ class PluginExecutionFailed(Flake8Exception):
             "name": self.plugin["plugin_name"],
             "exc": self.original_exception,
         }
-
-
-class HookInstallationError(Flake8Exception):
-    """Parent exception for all hooks errors."""
-
-
-class GitHookAlreadyExists(HookInstallationError):
-    """Exception raised when the git pre-commit hook file already exists."""
-
-    def __init__(self, path):  # type: (str) -> None
-        """Initialize the exception message from the `path`."""
-        self.path = path
-        tmpl = (
-            "The Git pre-commit hook ({0}) already exists. To convince "
-            "Flake8 to install the hook, please remove the existing "
-            "hook."
-        )
-        super(GitHookAlreadyExists, self).__init__(tmpl.format(self.path))
-
-
-class MercurialHookAlreadyExists(HookInstallationError):
-    """Exception raised when a mercurial hook is already configured."""
-
-    hook_name = None  # type: str
-
-    def __init__(self, path, value):  # type: (str, str) -> None
-        """Initialize the relevant attributes."""
-        self.path = path
-        self.value = value
-        tmpl = (
-            'The Mercurial {0} hook already exists with "{1}" in {2}. '
-            "To convince Flake8 to install the hook, please remove the "
-            "{0} configuration from the [hooks] section of your hgrc."
-        )
-        msg = tmpl.format(self.hook_name, self.value, self.path)
-        super(MercurialHookAlreadyExists, self).__init__(msg)
-
-
-class MercurialCommitHookAlreadyExists(MercurialHookAlreadyExists):
-    """Exception raised when the hg commit hook is already configured."""
-
-    hook_name = "commit"
-
-
-class MercurialQRefreshHookAlreadyExists(MercurialHookAlreadyExists):
-    """Exception raised when the hg commit hook is already configured."""
-
-    hook_name = "qrefresh"
diff --git a/src/flake8/main/application.py b/src/flake8/main/application.py
index 5c9e076..a247062 100644
--- a/src/flake8/main/application.py
+++ b/src/flake8/main/application.py
@@ -191,8 +191,6 @@ class Application(object):
             if not self.parsed_diff:
                 self.exit()
 
-        self.options._running_from_vcs = False
-
         self.check_plugins.provide_options(
             self.option_manager, self.options, self.args
         )
diff --git a/src/flake8/main/git.py b/src/flake8/main/git.py
deleted file mode 100644
index 683396a..0000000
--- a/src/flake8/main/git.py
+++ /dev/null
@@ -1,262 +0,0 @@
-"""Module containing the main git hook interface and helpers.
-
-.. autofunction:: hook
-.. autofunction:: install
-
-"""
-import contextlib
-import os
-import os.path
-import shutil
-import stat
-import subprocess
-import sys
-import tempfile
-
-from flake8 import defaults
-from flake8 import exceptions
-
-__all__ = ("hook", "install")
-
-
-def hook(lazy=False, strict=False):
-    """Execute Flake8 on the files in git's index.
-
-    Determine which files are about to be committed and run Flake8 over them
-    to check for violations.
-
-    :param bool lazy:
-        Find files not added to the index prior to committing. This is useful
-        if you frequently use ``git commit -a`` for example. This defaults to
-        False since it will otherwise include files not in the index.
-    :param bool strict:
-        If True, return the total number of errors/violations found by Flake8.
-        This will cause the hook to fail.
-    :returns:
-        Total number of errors found during the run.
-    :rtype:
-        int
-    """
-    # NOTE(sigmavirus24): Delay import of application until we need it.
-    from flake8.main import application
-
-    app = application.Application()
-    with make_temporary_directory() as tempdir:
-        filepaths = list(copy_indexed_files_to(tempdir, lazy))
-        app.initialize(["."])
-        app.options.exclude = update_excludes(app.options.exclude, tempdir)
-        app.options._running_from_vcs = True
-        # Apparently there are times when there are no files to check (e.g.,
-        # when amending a commit). In those cases, let's not try to run checks
-        # against nothing.
-        if filepaths:
-            app.run_checks(filepaths)
-
-    # If there were files to check, update their paths and report the errors
-    if filepaths:
-        update_paths(app.file_checker_manager, tempdir)
-        app.report_errors()
-
-    if strict:
-        return app.result_count
-    return 0
-
-
-def install():
-    """Install the git hook script.
-
-    This searches for the ``.git`` directory and will install an executable
-    pre-commit python script in the hooks sub-directory if one does not
-    already exist.
-
-    It will also print a message to stdout about how to configure the hook.
-
-    :returns:
-        True if successful, False if the git directory doesn't exist.
-    :rtype:
-        bool
-    :raises:
-        flake8.exceptions.GitHookAlreadyExists
-    """
-    git_directory = find_git_directory()
-    if git_directory is None or not os.path.exists(git_directory):
-        return False
-
-    hooks_directory = os.path.join(git_directory, "hooks")
-    if not os.path.exists(hooks_directory):
-        os.mkdir(hooks_directory)
-
-    pre_commit_file = os.path.abspath(
-        os.path.join(hooks_directory, "pre-commit")
-    )
-    if os.path.exists(pre_commit_file):
-        raise exceptions.GitHookAlreadyExists(path=pre_commit_file)
-
-    executable = get_executable()
-
-    with open(pre_commit_file, "w") as fd:
-        fd.write(_HOOK_TEMPLATE.format(executable=executable))
-
-    # NOTE(sigmavirus24): The following sets:
-    # - read, write, and execute permissions for the owner
-    # - read permissions for people in the group
-    # - read permissions for other people
-    # The owner needs the file to be readable, writable, and executable
-    # so that git can actually execute it as a hook.
-    pre_commit_permissions = stat.S_IRWXU | stat.S_IRGRP | stat.S_IROTH
-    os.chmod(pre_commit_file, pre_commit_permissions)
-
-    print("git pre-commit hook installed, for configuration options see")
-    print("http://flake8.pycqa.org/en/latest/user/using-hooks.html")
-
-    return True
-
-
-def get_executable():
-    if sys.executable is not None:
-        return sys.executable
-    return "/usr/bin/env python"
-
-
-def find_git_directory():
-    rev_parse = piped_process(["git", "rev-parse", "--git-dir"])
-
-    (stdout, _) = rev_parse.communicate()
-    stdout = to_text(stdout)
-
-    if rev_parse.returncode == 0:
-        return stdout.strip()
-    return None
-
-
-def copy_indexed_files_to(temporary_directory, lazy):
-    # some plugins (e.g. flake8-isort) need these files to run their checks
-    setup_cfgs = find_setup_cfgs(lazy)
-    for filename in setup_cfgs:
-        contents = get_staged_contents_from(filename)
-        copy_file_to(temporary_directory, filename, contents)
-
-    modified_files = find_modified_files(lazy)
-    for filename in modified_files:
-        contents = get_staged_contents_from(filename)
-        yield copy_file_to(temporary_directory, filename, contents)
-
-
-def copy_file_to(destination_directory, filepath, contents):
-    directory, filename = os.path.split(os.path.abspath(filepath))
-    temporary_directory = make_temporary_directory_from(
-        destination_directory, directory
-    )
-    if not os.path.exists(temporary_directory):
-        os.makedirs(temporary_directory)
-    temporary_filepath = os.path.join(temporary_directory, filename)
-    with open(temporary_filepath, "wb") as fd:
-        fd.write(contents)
-    return temporary_filepath
-
-
-def make_temporary_directory_from(destination, directory):
-    prefix = os.path.commonprefix([directory, destination])
-    common_directory_path = os.path.relpath(directory, start=prefix)
-    return os.path.join(destination, common_directory_path)
-
-
-def find_modified_files(lazy):
-    diff_index_cmd = [
-        "git",
-        "diff-index",
-        "--cached",
-        "--name-only",
-        "--diff-filter=ACMRTUXB",
-        "HEAD",
-    ]
-    if lazy:
-        diff_index_cmd.remove("--cached")
-
-    diff_index = piped_process(diff_index_cmd)
-    (stdout, _) = diff_index.communicate()
-    stdout = to_text(stdout)
-    return stdout.splitlines()
-
-
-def find_setup_cfgs(lazy):
-    setup_cfg_cmd = ["git", "ls-files", "--cached", "*setup.cfg"]
-    if lazy:
-        setup_cfg_cmd.remove("--cached")
-    extra_files = piped_process(setup_cfg_cmd)
-    (stdout, _) = extra_files.communicate()
-    stdout = to_text(stdout)
-    return stdout.splitlines()
-
-
-def get_staged_contents_from(filename):
-    git_show = piped_process(["git", "show", ":{0}".format(filename)])
-    (stdout, _) = git_show.communicate()
-    return stdout
-
-
-@contextlib.contextmanager
-def make_temporary_directory():
-    temporary_directory = tempfile.mkdtemp()
-    yield temporary_directory
-    shutil.rmtree(temporary_directory, ignore_errors=True)
-
-
-def to_text(string):
-    """Ensure that the string is text."""
-    if callable(getattr(string, "decode", None)):
-        return string.decode("utf-8")
-    return string
-
-
-def piped_process(command):
-    return subprocess.Popen(
-        command, stdout=subprocess.PIPE, stderr=subprocess.PIPE
-    )
-
-
-def git_config_for(parameter):
-    config = piped_process(["git", "config", "--get", "--bool", parameter])
-    (stdout, _) = config.communicate()
-    return to_text(stdout).strip()
-
-
-def config_for(parameter):
-    environment_variable = "flake8_{0}".format(parameter).upper()
-    git_variable = "flake8.{0}".format(parameter)
-    value = os.environ.get(environment_variable, git_config_for(git_variable))
-    return value.lower() in defaults.TRUTHY_VALUES
-
-
-def update_excludes(exclude_list, temporary_directory_path):
-    return [
-        (temporary_directory_path + pattern)
-        if os.path.isabs(pattern)
-        else pattern
-        for pattern in exclude_list
-    ]
-
-
-def update_paths(checker_manager, temp_prefix):
-    temp_prefix_length = len(temp_prefix)
-    for checker in checker_manager.checkers:
-        filename = checker.display_name
-        if filename.startswith(temp_prefix):
-            checker.display_name = os.path.relpath(
-                filename[temp_prefix_length:]
-            )
-
-
-_HOOK_TEMPLATE = """#!{executable}
-import sys
-
-from flake8.main import git
-
-if __name__ == '__main__':
-    sys.exit(
-        git.hook(
-            strict=git.config_for('strict'),
-            lazy=git.config_for('lazy'),
-        )
-    )
-"""
diff --git a/src/flake8/main/mercurial.py b/src/flake8/main/mercurial.py
deleted file mode 100644
index c387e84..0000000
--- a/src/flake8/main/mercurial.py
+++ /dev/null
@@ -1,145 +0,0 @@
-"""Module containing the main mecurial hook interface and helpers.
-
-.. autofunction:: hook
-.. autofunction:: install
-
-"""
-import configparser
-import os
-import subprocess
-from typing import Set
-
-from flake8 import exceptions as exc
-
-__all__ = ("hook", "install")
-
-
-def hook(ui, repo, **kwargs):
-    """Execute Flake8 on the repository provided by Mercurial.
-
-    To understand the parameters read more of the Mercurial documentation
-    around Hooks: https://www.mercurial-scm.org/wiki/Hook.
-
-    We avoid using the ``ui`` attribute because it can cause issues with
-    the GPL license that Mercurial is under. We don't import it, but we
-    avoid using it all the same.
-    """
-    from flake8.main import application
-
-    hgrc = find_hgrc(create_if_missing=False)
-    if hgrc is None:
-        print("Cannot locate your root mercurial repository.")
-        raise SystemExit(True)
-
-    hgconfig = configparser_for(hgrc)
-    strict = hgconfig.get("flake8", "strict", fallback=True)
-
-    filenames = list(get_filenames_from(repo, kwargs))
-
-    app = application.Application()
-    app.initialize(filenames)
-    app.options._running_from_vcs = True
-    app.run_checks()
-    app.report()
-
-    if strict:
-        return app.result_count
-    return 0
-
-
-def install():
-    """Ensure that the mercurial hooks are installed.
-
-    This searches for the ``.hg/hgrc`` configuration file and will add commit
-    and qrefresh hooks to it, if they do not already exist.
-
-    It will also print a message to stdout about how to configure the hook.
-
-    :returns:
-        True if successful, False if the ``.hg/hgrc`` file doesn't exist.
-    :rtype:
-        bool
-    :raises:
-        flake8.exceptions.MercurialCommitHookAlreadyExists
-    :raises:
-        flake8.exceptions.MercurialQRefreshHookAlreadyExists
-    """
-    hgrc = find_hgrc(create_if_missing=True)
-    if hgrc is None:
-        return False
-
-    hgconfig = configparser_for(hgrc)
-
-    if not hgconfig.has_section("hooks"):
-        hgconfig.add_section("hooks")
-
-    if hgconfig.has_option("hooks", "commit"):
-        raise exc.MercurialCommitHookAlreadyExists(
-            path=hgrc, value=hgconfig.get("hooks", "commit")
-        )
-
-    if hgconfig.has_option("hooks", "qrefresh"):
-        raise exc.MercurialQRefreshHookAlreadyExists(
-            path=hgrc, value=hgconfig.get("hooks", "qrefresh")
-        )
-
-    hgconfig.set("hooks", "commit", "python:flake8.main.mercurial.hook")
-    hgconfig.set("hooks", "qrefresh", "python:flake8.main.mercurial.hook")
-
-    if not hgconfig.has_section("flake8"):
-        hgconfig.add_section("flake8")
-
-    if not hgconfig.has_option("flake8", "strict"):
-        hgconfig.set("flake8", "strict", False)
-
-    with open(hgrc, "w") as fd:
-        hgconfig.write(fd)
-
-    print("mercurial hooks installed, for configuration options see")
-    print("http://flake8.pycqa.org/en/latest/user/using-hooks.html")
-
-    return True
-
-
-def get_filenames_from(repository, kwargs):
-    seen_filenames = set()  # type: Set[str]
-    node = kwargs["node"]
-    for revision in range(repository[node], len(repository)):
-        for filename in repository[revision].files():
-            full_filename = os.path.join(repository.root, filename)
-            have_seen_filename = full_filename in seen_filenames
-            filename_does_not_exist = not os.path.exists(full_filename)
-            if have_seen_filename or filename_does_not_exist:
-                continue
-
-            seen_filenames.add(full_filename)
-            if full_filename.endswith(".py"):
-                yield full_filename
-
-
-def find_hgrc(create_if_missing=False):
-    root = subprocess.Popen(
-        ["hg", "root"], stdout=subprocess.PIPE, stderr=subprocess.PIPE
-    )
-
-    (hg_directory, _) = root.communicate()
-    if callable(getattr(hg_directory, "decode", None)):
-        hg_directory = hg_directory.decode("utf-8")
-
-    if not os.path.isdir(hg_directory):
-        return None
-
-    hgrc = os.path.abspath(os.path.join(hg_directory, ".hg", "hgrc"))
-    if not os.path.exists(hgrc):
-        if create_if_missing:
-            open(hgrc, "w").close()
-        else:
-            return None
-
-    return hgrc
-
-
-def configparser_for(path):
-    parser = configparser.ConfigParser(interpolation=None)
-    parser.read(path)
-    return parser
diff --git a/src/flake8/main/options.py b/src/flake8/main/options.py
index 0a6ad45..fdde9e1 100644
--- a/src/flake8/main/options.py
+++ b/src/flake8/main/options.py
@@ -4,7 +4,6 @@ import functools
 
 from flake8 import defaults
 from flake8.main import debug
-from flake8.main import vcs
 
 
 def register_preliminary_options(parser):
@@ -323,14 +322,6 @@ def register_default_options(option_manager):
     )
 
     add_option(
-        "--install-hook",
-        action=vcs.InstallAction,
-        choices=vcs.choices(),
-        help="Install a hook that is run prior to a commit for the supported "
-        "version control system.",
-    )
-
-    add_option(
         "-j",
         "--jobs",
         default="auto",
diff --git a/src/flake8/main/vcs.py b/src/flake8/main/vcs.py
deleted file mode 100644
index bf15395..0000000
--- a/src/flake8/main/vcs.py
+++ /dev/null
@@ -1,48 +0,0 @@
-"""Module containing some of the logic for our VCS installation logic."""
-from __future__ import print_function
-
-import argparse
-import sys
-
-from flake8 import exceptions as exc
-from flake8.main import git
-from flake8.main import mercurial
-
-
-# NOTE(sigmavirus24): In the future, we may allow for VCS hooks to be defined
-# as plugins, e.g., adding a flake8.vcs entry-point. In that case, this
-# dictionary should disappear, and this module might contain more code for
-# managing those bits (in conjunction with flake8.plugins.manager).
-_INSTALLERS = {"git": git.install, "mercurial": mercurial.install}
-
-
-class InstallAction(argparse.Action):
-    """argparse action to run the hook installation."""
-
-    def __call__(self, parser, namespace, value, option_string=None):
-        """Perform the argparse action for installing vcs hooks."""
-        installer = _INSTALLERS[value]
-        errored = False
-        successful = False
-        try:
-            successful = installer()
-        except exc.HookInstallationError as hook_error:
-            print(str(hook_error))
-            errored = True
-
-        if not successful:
-            print("Could not find the {0} directory".format(value))
-
-        print(
-            "\nWARNING: flake8 vcs hooks integration is deprecated and "
-            "scheduled for removal in 4.x.  For more information, see "
-            "https://gitlab.com/pycqa/flake8/issues/568",
-            file=sys.stderr,
-        )
-
-        raise SystemExit(not successful and errored)
-
-
-def choices():
-    """Return the list of VCS choices."""
-    return list(_INSTALLERS)
diff --git a/src/flake8/plugins/pyflakes.py b/src/flake8/plugins/pyflakes.py
index b9b30d0..e845483 100644
--- a/src/flake8/plugins/pyflakes.py
+++ b/src/flake8/plugins/pyflakes.py
@@ -2,13 +2,6 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import
 
-try:
-    # The 'demandimport' breaks pyflakes and flake8.plugins.pyflakes
-    from mercurial import demandimport
-except ImportError:
-    pass
-else:
-    demandimport.disable()
 import os
 from typing import List
 
diff --git a/tests/unit/test_git.py b/tests/unit/test_git.py
deleted file mode 100644
index 24d4b5b..0000000
--- a/tests/unit/test_git.py
+++ /dev/null
@@ -1,29 +0,0 @@
-"""Tests around functionality in the git integration."""
-import mock
-import pytest
-
-from flake8.main import git
-
-
-@pytest.mark.parametrize('lazy', [True, False])
-def test_find_modified_files(lazy):
-    """Confirm our logic for listing modified files."""
-    if lazy:
-        # Here --cached is missing
-        call = [
-            'git', 'diff-index', '--name-only', '--diff-filter=ACMRTUXB',
-            'HEAD'
-        ]
-    else:
-        call = [
-            'git', 'diff-index', '--cached', '--name-only',
-            '--diff-filter=ACMRTUXB', 'HEAD'
-        ]
-    mocked_popen = mock.Mock()
-    mocked_popen.communicate.return_value = ('', '')
-
-    with mock.patch('flake8.main.git.piped_process') as piped_process:
-        piped_process.return_value = mocked_popen
-        git.find_modified_files(lazy)
-
-    piped_process.assert_called_once_with(call)