mypy passes with check_untyped_defs

.gitignore

@@ -1,14 +1,8 @@
 *.egg-info
-*.iml
 *.py[co]
-.*.sw[a-z]
-.coverage
-.idea
-.project
-.pydevproject
-.tox
-.venv.touch
+/.coverage
+/.mypy_cache
+/.pytest_cache
+/.tox
+/dist
 /venv*
-coverage-html
-dist
-.pytest_cache

.pre-commit-config.yaml

@@ -42,6 +42,11 @@ repos:
     rev: v1.6.0
     hooks:
     -   id: setup-cfg-fmt
+-   repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v0.761
+    hooks:
+    -   id: mypy
+        exclude: ^testing/resources/
 -   repo: meta
     hooks:
     -   id: check-hooks-apply

pre_commit/color.py

@@ -2,7 +2,7 @@ import os
 import sys
 
 terminal_supports_color = True
-if os.name == 'nt':  # pragma: no cover (windows)
+if sys.platform == 'win32':  # pragma: no cover (windows)
     from pre_commit.color_windows import enable_virtual_terminal_processing
     try:
         enable_virtual_terminal_processing()

pre_commit/color_windows.py

@@ -1,10 +1,14 @@
-from ctypes import POINTER
-from ctypes import windll
-from ctypes import WinError
-from ctypes import WINFUNCTYPE
-from ctypes.wintypes import BOOL
-from ctypes.wintypes import DWORD
-from ctypes.wintypes import HANDLE
+import sys
+assert sys.platform == 'win32'
+
+from ctypes import POINTER  # noqa: E402
+from ctypes import windll  # noqa: E402
+from ctypes import WinError  # noqa: E402
+from ctypes import WINFUNCTYPE  # noqa: E402
+from ctypes.wintypes import BOOL  # noqa: E402
+from ctypes.wintypes import DWORD  # noqa: E402
+from ctypes.wintypes import HANDLE  # noqa: E402
+
 
 STD_OUTPUT_HANDLE = -11
 ENABLE_VIRTUAL_TERMINAL_PROCESSING = 4

pre_commit/commands/autoupdate.py

@@ -1,6 +1,8 @@
 import collections
 import os.path
 import re
+from typing import List
+from typing import Optional
 
 from aspy.yaml import ordered_dump
 from aspy.yaml import ordered_load
@@ -121,7 +123,7 @@ def autoupdate(config_file, store, tags_only, freeze, repos=()):
     """Auto-update the pre-commit config to the latest versions of repos."""
     migrate_config(config_file, quiet=True)
     retv = 0
-    rev_infos = []
+    rev_infos: List[Optional[RevInfo]] = []
     changed = False
 
     config = load_config(config_file)

pre_commit/envcontext.py

@@ -1,13 +1,26 @@
-import collections
 import contextlib
+import enum
 import os
+from typing import NamedTuple
+from typing import Tuple
+from typing import Union
 
 
-UNSET = collections.namedtuple('UNSET', ())()
+class _Unset(enum.Enum):
+    UNSET = 1
 
 
-Var = collections.namedtuple('Var', ('name', 'default'))
-Var.__new__.__defaults__ = ('',)
+UNSET = _Unset.UNSET
+
+
+class Var(NamedTuple):
+    name: str
+    default: str = ''
+
+
+SubstitutionT = Tuple[Union[str, Var], ...]
+ValueT = Union[str, _Unset, SubstitutionT]
+PatchesT = Tuple[Tuple[str, ValueT], ...]
 
 
 def format_env(parts, env):

pre_commit/error_handler.py

@@ -2,6 +2,7 @@ import contextlib
 import os.path
 import sys
 import traceback
+from typing import Union
 
 import pre_commit.constants as C
 from pre_commit import five
@@ -32,8 +33,8 @@ def _log_and_exit(msg, exc, formatted):
     output.write_line(f'Check the log at {log_path}')
 
     with open(log_path, 'wb') as log:
-        def _log_line(*s):  # type: (*str) -> None
-            output.write_line(*s, stream=log)
+        def _log_line(s: Union[None, str, bytes] = None) -> None:
+            output.write_line(s, stream=log)
 
         _log_line('### version information')
         _log_line()

pre_commit/file_lock.py

@@ -1,8 +1,9 @@
 import contextlib
 import errno
+import os
 
 
-try:  # pragma: no cover (windows)
+if os.name == 'nt':  # pragma: no cover (windows)
     import msvcrt
 
     # https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/locking
@@ -14,12 +15,14 @@ try:  # pragma: no cover (windows)
     @contextlib.contextmanager
     def _locked(fileno, blocked_cb):
         try:
-            msvcrt.locking(fileno, msvcrt.LK_NBLCK, _region)
+            # TODO: https://github.com/python/typeshed/pull/3607
+            msvcrt.locking(fileno, msvcrt.LK_NBLCK, _region)  # type: ignore
         except OSError:
             blocked_cb()
             while True:
                 try:
-                    msvcrt.locking(fileno, msvcrt.LK_LOCK, _region)
+                    # TODO: https://github.com/python/typeshed/pull/3607
+                    msvcrt.locking(fileno, msvcrt.LK_LOCK, _region)  # type: ignore  # noqa: E501
                 except OSError as e:
                     # Locking violation. Returned when the _LK_LOCK or _LK_RLCK
                     # flag is specified and the file cannot be locked after 10
@@ -37,8 +40,9 @@ try:  # pragma: no cover (windows)
             # The documentation however states:
             # "Regions should be locked only briefly and should be unlocked
             # before closing a file or exiting the program."
-            msvcrt.locking(fileno, msvcrt.LK_UNLCK, _region)
-except ImportError:  # pragma: windows no cover
+            # TODO: https://github.com/python/typeshed/pull/3607
+            msvcrt.locking(fileno, msvcrt.LK_UNLCK, _region)  # type: ignore
+else:  # pramga: windows no cover
     import fcntl
 
     @contextlib.contextmanager

pre_commit/languages/all.py

@@ -1,3 +1,6 @@
+from typing import Any
+from typing import Dict
+
 from pre_commit.languages import conda
 from pre_commit.languages import docker
 from pre_commit.languages import docker_image
@@ -13,6 +16,7 @@ from pre_commit.languages import script
 from pre_commit.languages import swift
 from pre_commit.languages import system
 
+
 # A language implements the following constant and functions in its module:
 #
 # # Use None for no environment
@@ -49,7 +53,7 @@ from pre_commit.languages import system
 #         (returncode, output)
 #     """
 
-languages = {
+languages: Dict[str, Any] = {
     'conda': conda,
     'docker': docker,
     'docker_image': docker_image,

pre_commit/languages/conda.py

@@ -2,6 +2,7 @@ import contextlib
 import os
 
 from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import SubstitutionT
 from pre_commit.envcontext import UNSET
 from pre_commit.envcontext import Var
 from pre_commit.languages import helpers
@@ -18,7 +19,7 @@ def get_env_patch(env):
     # they can be in $CONDA_PREFIX/bin, $CONDA_PREFIX/Library/bin,
     # $CONDA_PREFIX/Scripts and $CONDA_PREFIX. Whereas the latter only
     # seems to be used for python.exe.
-    path = (os.path.join(env, 'bin'), os.pathsep, Var('PATH'))
+    path: SubstitutionT = (os.path.join(env, 'bin'), os.pathsep, Var('PATH'))
     if os.name == 'nt':  # pragma: no cover (platform specific)
         path = (env, os.pathsep) + path
         path = (os.path.join(env, 'Scripts'), os.pathsep) + path

pre_commit/languages/docker.py

@@ -1,5 +1,6 @@
 import hashlib
 import os
+from typing import Tuple
 
 import pre_commit.constants as C
 from pre_commit import five
@@ -42,7 +43,7 @@ def assert_docker_available():  # pragma: windows no cover
 def build_docker_image(prefix, **kwargs):  # pragma: windows no cover
     pull = kwargs.pop('pull')
     assert not kwargs, kwargs
-    cmd = (
+    cmd: Tuple[str, ...] = (
         'docker', 'build',
         '--tag', docker_tag(prefix),
         '--label', PRE_COMMIT_LABEL,

pre_commit/languages/python.py

@@ -1,4 +1,5 @@
 import contextlib
+import functools
 import os
 import sys
 
@@ -64,7 +65,8 @@ def _find_by_sys_executable():
     return None
 
 
-def _get_default_version():  # pragma: no cover (platform dependent)
+@functools.lru_cache(maxsize=1)
+def get_default_version():  # pragma: no cover (platform dependent)
     # First attempt from `sys.executable` (or the realpath)
     exe = _find_by_sys_executable()
     if exe:
@@ -86,15 +88,6 @@ def _get_default_version():  # pragma: no cover (platform dependent)
     return C.DEFAULT
 
 
-def get_default_version():
-    # TODO: when dropping python2, use `functools.lru_cache(maxsize=1)`
-    try:
-        return get_default_version.cached_version
-    except AttributeError:
-        get_default_version.cached_version = _get_default_version()
-        return get_default_version()
-
-
 def _sys_executable_matches(version):
     if version == 'python':
         return True

pre_commit/languages/ruby.py

@@ -5,6 +5,7 @@ import tarfile
 
 import pre_commit.constants as C
 from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import PatchesT
 from pre_commit.envcontext import Var
 from pre_commit.languages import helpers
 from pre_commit.util import CalledProcessError
@@ -18,7 +19,7 @@ healthy = helpers.basic_healthy
 
 
 def get_env_patch(venv, language_version):  # pragma: windows no cover
-    patches = (
+    patches: PatchesT = (
         ('GEM_HOME', os.path.join(venv, 'gems')),
         ('RBENV_ROOT', venv),
         ('BUNDLE_IGNORE_CONFIG', '1'),

pre_commit/languages/rust.py

@@ -1,5 +1,7 @@
 import contextlib
 import os.path
+from typing import Set
+from typing import Tuple
 
 import toml
 
@@ -71,7 +73,7 @@ def install_environment(prefix, version, additional_dependencies):
         _add_dependencies(prefix.path('Cargo.toml'), lib_deps)
 
     with clean_path_on_failure(directory):
-        packages_to_install = {('--path', '.')}
+        packages_to_install: Set[Tuple[str, ...]] = {('--path', '.')}
         for cli_dep in cli_deps:
             cli_dep = cli_dep[len('cli:'):]
             package, _, version = cli_dep.partition(':')

pre_commit/output.py

@@ -1,8 +1,8 @@
+import contextlib
 import sys
 
 from pre_commit import color
 from pre_commit import five
-from pre_commit.util import noop_context
 
 
 def get_hook_message(
@@ -71,14 +71,12 @@ def write(s, stream=stdout_byte_stream):
 
 
 def write_line(s=None, stream=stdout_byte_stream, logfile_name=None):
-    output_streams = [stream]
-    if logfile_name:
-        ctx = open(logfile_name, 'ab')
-        output_streams.append(ctx)
-    else:
-        ctx = noop_context()
+    with contextlib.ExitStack() as exit_stack:
+        output_streams = [stream]
+        if logfile_name:
+            stream = exit_stack.enter_context(open(logfile_name, 'ab'))
+            output_streams.append(stream)
 
-    with ctx:
         for output_stream in output_streams:
             if s is not None:
                 output_stream.write(five.to_bytes(s))

pre_commit/repository.py

@@ -1,8 +1,10 @@
-import collections
 import json
 import logging
 import os
 import shlex
+from typing import NamedTuple
+from typing import Sequence
+from typing import Set
 
 import pre_commit.constants as C
 from pre_commit import five
@@ -49,8 +51,29 @@ def _write_state(prefix, venv, state):
 _KEYS = tuple(item.key for item in MANIFEST_HOOK_DICT.items)
 
 
-class Hook(collections.namedtuple('Hook', ('src', 'prefix') + _KEYS)):
-    __slots__ = ()
+class Hook(NamedTuple):
+    src: str
+    prefix: Prefix
+    id: str
+    name: str
+    entry: str
+    language: str
+    alias: str
+    files: str
+    exclude: str
+    types: Sequence[str]
+    exclude_types: Sequence[str]
+    additional_dependencies: Sequence[str]
+    args: Sequence[str]
+    always_run: bool
+    pass_filenames: bool
+    description: str
+    language_version: str
+    log_file: str
+    minimum_pre_commit_version: str
+    require_serial: bool
+    stages: Sequence[str]
+    verbose: bool
 
     @property
     def cmd(self):
@@ -201,7 +224,7 @@ def _repository_hooks(repo_config, store, root_config):
 
 def install_hook_envs(hooks, store):
     def _need_installed():
-        seen = set()
+        seen: Set[Hook] = set()
         ret = []
         for hook in hooks:
             if hook.install_key not in seen and not hook.installed():

pre_commit/resources/hook-tmpl

@@ -4,6 +4,7 @@ import distutils.spawn
 import os
 import subprocess
 import sys
+from typing import Tuple
 
 # work around https://github.com/Homebrew/homebrew-core/issues/30445
 os.environ.pop('__PYVENV_LAUNCHER__', None)
@@ -12,10 +13,10 @@ HERE = os.path.dirname(os.path.abspath(__file__))
 Z40 = '0' * 40
 ID_HASH = '138fd403232d2ddd5efb44317e38bf03'
 # start templated
-CONFIG = None
-HOOK_TYPE = None
-INSTALL_PYTHON = None
-SKIP_ON_MISSING_CONFIG = None
+CONFIG = ''
+HOOK_TYPE = ''
+INSTALL_PYTHON = ''
+SKIP_ON_MISSING_CONFIG = False
 # end templated
 
 
@@ -123,7 +124,7 @@ def _rev_exists(rev):
 def _pre_push(stdin):
     remote = sys.argv[1]
 
-    opts = ()
+    opts: Tuple[str, ...] = ()
     for line in stdin.decode('UTF-8').splitlines():
         _, local_sha, _, remote_sha = line.split()
         if local_sha == Z40:
@@ -146,8 +147,8 @@ def _pre_push(stdin):
                     # pushing the whole tree including root commit
                     opts = ('--all-files',)
                 else:
-                    cmd = ('git', 'rev-parse', f'{first_ancestor}^')
-                    source = subprocess.check_output(cmd).decode().strip()
+                    rev_cmd = ('git', 'rev-parse', f'{first_ancestor}^')
+                    source = subprocess.check_output(rev_cmd).decode().strip()
                     opts = ('--origin', local_sha, '--source', source)
 
     if opts:

pre_commit/util.py

@@ -152,6 +152,7 @@ if os.name != 'nt':  # pragma: windows no cover
 
             # tty flags normally change \n to \r\n
             attrs = termios.tcgetattr(self.r)
+            assert isinstance(attrs[1], int)
             attrs[1] &= ~(termios.ONLCR | termios.OPOST)
             termios.tcsetattr(self.r, termios.TCSANOW, attrs)
 

pre_commit/xargs.py

@@ -4,6 +4,7 @@ import math
 import os
 import subprocess
 import sys
+from typing import List
 
 from pre_commit import parse_shebang
 from pre_commit.util import cmd_output_b
@@ -56,7 +57,7 @@ def partition(cmd, varargs, target_concurrency, _max_length=None):
     cmd = tuple(cmd)
     ret = []
 
-    ret_cmd = []
+    ret_cmd: List[str] = []
     # Reversed so arguments are in order
     varargs = list(reversed(varargs))
 

setup.cfg

@@ -52,3 +52,15 @@ exclude =
 
 [bdist_wheel]
 universal = True
+
+[mypy]
+check_untyped_defs = true
+disallow_any_generics = true
+disallow_incomplete_defs = true
+no_implicit_optional = true
+
+[mypy-testing.*]
+disallow_untyped_defs = false
+
+[mypy-tests.*]
+disallow_untyped_defs = false

tests/languages/all_test.py

@@ -18,7 +18,7 @@ def test_install_environment_argspec(language):
     expected_argspec = ArgSpec(
         args=['prefix', 'version', 'additional_dependencies'],
     )
-    argspec = inspect.getfullargpsec(languages[language].install_environment)
+    argspec = inspect.getfullargspec(languages[language].install_environment)
     assert argspec == expected_argspec
 
 
@@ -28,21 +28,21 @@ def test_ENVIRONMENT_DIR(language):
 
 
 @pytest.mark.parametrize('language', all_languages)
-def test_run_hook_argpsec(language):
+def test_run_hook_argspec(language):
     expected_argspec = ArgSpec(args=['hook', 'file_args', 'color'])
-    argspec = inspect.getfullargpsec(languages[language].run_hook)
+    argspec = inspect.getfullargspec(languages[language].run_hook)
     assert argspec == expected_argspec
 
 
 @pytest.mark.parametrize('language', all_languages)
 def test_get_default_version_argspec(language):
     expected_argspec = ArgSpec(args=[])
-    argspec = inspect.getfullargpsec(languages[language].get_default_version)
+    argspec = inspect.getfullargspec(languages[language].get_default_version)
     assert argspec == expected_argspec
 
 
 @pytest.mark.parametrize('language', all_languages)
 def test_healthy_argspec(language):
     expected_argspec = ArgSpec(args=['prefix', 'language_version'])
-    argspec = inspect.getfullargpsec(languages[language].healthy)
+    argspec = inspect.getfullargspec(languages[language].healthy)
     assert argspec == expected_argspec

tests/main_test.py

@@ -1,5 +1,8 @@
 import argparse
 import os.path
+from typing import NamedTuple
+from typing import Optional
+from typing import Sequence
 from unittest import mock
 
 import pytest
@@ -24,11 +27,11 @@ def test_append_replace_default(argv, expected):
     assert parser.parse_args(argv).f == expected
 
 
-class Args:
-    def __init__(self, **kwargs):
-        kwargs.setdefault('command', 'help')
-        kwargs.setdefault('config', C.CONFIG_FILE)
-        self.__dict__.update(kwargs)
+class Args(NamedTuple):
+    command: str = 'help'
+    config: str = C.CONFIG_FILE
+    files: Sequence[str] = []
+    repo: Optional[str] = None
 
 
 def test_adjust_args_and_chdir_not_in_git_dir(in_tmpdir):
@@ -73,6 +76,7 @@ def test_adjust_args_try_repo_repo_relative(in_git_dir):
     in_git_dir.join('foo').ensure_dir().chdir()
 
     args = Args(command='try-repo', repo='../foo', files=[])
+    assert args.repo is not None
     assert os.path.exists(args.repo)
     main._adjust_args_and_chdir(args)
     assert os.getcwd() == in_git_dir

tests/parse_shebang_test.py

@@ -11,6 +11,12 @@ from pre_commit.envcontext import Var
 from pre_commit.util import make_executable
 
 
+def _echo_exe() -> str:
+    exe = distutils.spawn.find_executable('echo')
+    assert exe is not None
+    return exe
+
+
 def test_file_doesnt_exist():
     assert parse_shebang.parse_filename('herp derp derp') == ()
 
@@ -27,8 +33,7 @@ def test_find_executable_full_path():
 
 
 def test_find_executable_on_path():
-    expected = distutils.spawn.find_executable('echo')
-    assert parse_shebang.find_executable('echo') == expected
+    assert parse_shebang.find_executable('echo') == _echo_exe()
 
 
 def test_find_executable_not_found_none():
@@ -110,30 +115,29 @@ def test_normexe_already_full_path():
 
 
 def test_normexe_gives_full_path():
-    expected = distutils.spawn.find_executable('echo')
-    assert parse_shebang.normexe('echo') == expected
-    assert os.sep in expected
+    assert parse_shebang.normexe('echo') == _echo_exe()
+    assert os.sep in _echo_exe()
 
 
 def test_normalize_cmd_trivial():
-    cmd = (distutils.spawn.find_executable('echo'), 'hi')
+    cmd = (_echo_exe(), 'hi')
     assert parse_shebang.normalize_cmd(cmd) == cmd
 
 
 def test_normalize_cmd_PATH():
     cmd = ('echo', '--version')
-    expected = (distutils.spawn.find_executable('echo'), '--version')
+    expected = (_echo_exe(), '--version')
     assert parse_shebang.normalize_cmd(cmd) == expected
 
 
 def test_normalize_cmd_shebang(in_tmpdir):
-    echo = distutils.spawn.find_executable('echo').replace(os.sep, '/')
+    echo = _echo_exe().replace(os.sep, '/')
     path = write_executable(echo)
     assert parse_shebang.normalize_cmd((path,)) == (echo, path)
 
 
 def test_normalize_cmd_PATH_shebang_full_path(in_tmpdir):
-    echo = distutils.spawn.find_executable('echo').replace(os.sep, '/')
+    echo = _echo_exe().replace(os.sep, '/')
     path = write_executable(echo)
     with bin_on_path():
         ret = parse_shebang.normalize_cmd(('run',))
@@ -141,7 +145,7 @@ def test_normalize_cmd_PATH_shebang_full_path(in_tmpdir):
 
 
 def test_normalize_cmd_PATH_shebang_PATH(in_tmpdir):
-    echo = distutils.spawn.find_executable('echo')
+    echo = _echo_exe()
     path = write_executable('/usr/bin/env echo')
     with bin_on_path():
         ret = parse_shebang.normalize_cmd(('run',))

tests/repository_test.py

@@ -2,6 +2,8 @@ import os.path
 import re
 import shutil
 import sys
+from typing import Any
+from typing import Dict
 from unittest import mock
 
 import cfgv
@@ -763,7 +765,7 @@ def test_local_python_repo(store, local_python_config):
 
 
 def test_default_language_version(store, local_python_config):
-    config = {
+    config: Dict[str, Any] = {
         'default_language_version': {'python': 'fake'},
         'default_stages': ['commit'],
         'repos': [local_python_config],
@@ -780,7 +782,7 @@ def test_default_language_version(store, local_python_config):
 
 
 def test_default_stages(store, local_python_config):
-    config = {
+    config: Dict[str, Any] = {
         'default_language_version': {'python': C.DEFAULT},
         'default_stages': ['commit'],
         'repos': [local_python_config],

tests/staged_files_only_test.py

@@ -24,7 +24,8 @@ def patch_dir(tempdir_factory):
 
 def get_short_git_status():
     git_status = cmd_output('git', 'status', '-s')[1]
-    return dict(reversed(line.split()) for line in git_status.splitlines())
+    line_parts = [line.split() for line in git_status.splitlines()]
+    return {v: k for k, v in line_parts}
 
 
 @pytest.fixture