Add initial skeleton

.coveragerc

+[run]
+branch = True
+source =
+    .
+omit =
+    .tox/*
+    /usr/*
+    */tmp*
+    setup.py
+    # Don't complain if non-runnable code isn't run
+    */__main__.py
+
+[report]
+show_missing = True
+skip_covered = True
+exclude_lines =
+    # Have to re-enable the standard pragma
+    \#\s*pragma: no cover
+    # We optionally substitute this
+    ${COVERAGE_IGNORE_WINDOWS}
+
+    # Don't complain if tests don't hit defensive assertion code:
+    ^\s*raise AssertionError\b
+    ^\s*raise NotImplementedError\b
+    ^\s*return NotImplemented\b
+    ^\s*raise$
+
+    # Don't complain if non-runnable code isn't run:
+    ^if __name__ == ['"]__main__['"]:$
+
+[html]
+directory = coverage-html
+
+# vim:ft=dosini

.gitignore

+*.egg-info
+*.pyc
+/.cache
+/.coverage
+/.tox
+/venv*

.pre-commit-config.yaml

+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    sha: v0.7.1
+    hooks:
+    -   id: trailing-whitespace
+    -   id: end-of-file-fixer
+    -   id: autopep8-wrapper
+    -   id: check-docstring-first
+    -   id: check-yaml
+    -   id: debug-statements
+    -   id: name-tests-test
+    -   id: requirements-txt-fixer
+    -   id: flake8
+-   repo: https://github.com/asottile/reorder_python_imports
+    sha: v0.3.1
+    hooks:
+    -   id: reorder-python-imports

.pre-commit-hooks.yaml

+-   id: add-trailing-comma
+    name: add-trailing-comma
+    description: Automatically add trailing commas to calls and literals.
+    entry: add-trailing-comma
+    language: python
+    types: [python]

.travis.yml

+language: python
+matrix:
+    include:
+        -   env: TOXENV=py27
+        -   env: TOXENV=py35
+            python: 3.5
+        -   env: TOXENV=py36
+            python: 3.6
+        -   env: TOXENV=pypy
+install: pip install coveralls tox
+script: tox
+after_success: coveralls
+cache:
+    directories:
+        - $HOME/.cache/pip
+        - $HOME/.pre-commit

LICENSE

+Copyright (c) 2017 Anthony Sottile
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

+[![Build Status](https://travis-ci.org/asottile/add-trailing-comma.svg?branch=master)](https://travis-ci.org/asottile/add-trailing-comma)
+[![Coverage Status](https://coveralls.io/repos/github/asottile/add-trailing-comma/badge.svg?branch=master)](https://coveralls.io/github/asottile/add-trailing-comma?branch=master)
+
+add-trailing-comma
+=========
+
+A tool (and pre-commit hook) to automatically add trailing commas to calls and
+literals.
+
+## Installation
+
+`pip install add-trailing-comma`
+
+
+## As a pre-commit hook
+
+See [pre-commit](https://github.com/pre-commit/pre-commit) for instructions
+
+Sample `.pre-commit-config.yaml`:
+
+```yaml
+-   repo: https://github.com/asottile/add-trailing-comma
+    sha: v0.0.0
+    hooks:
+    -   id: add-trailing-comma
+```
+
+## TODO
+
+`--py35-plus` will append a trailing comma even after `*args` or `**kwargs`
+(this is a syntax error in older versions).

add_trailing_comma.py

+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import argparse
+import io
+
+
+def fix_file(filename, args):
+    with open(filename, 'rb') as f:
+        contents_bytes = f.read()
+
+    try:
+        contents_text_orig = contents_text = contents_bytes.decode('UTF-8')
+    except UnicodeDecodeError:
+        print('{} is non-utf-8 (not supported)'.format(filename))
+        return 1
+
+    if contents_text != contents_text_orig:
+        print('Rewriting {}'.format(filename))
+        with io.open(filename, 'w', encoding='UTF-8') as f:
+            f.write(contents_text)
+        return 1
+
+    return 0
+
+
+def main(argv=None):
+    parser = argparse.ArgumentParser()
+    parser.add_argument('filenames', nargs='*')
+    parser.add_argument('--py35-plus', action='store_true')
+    args = parser.parse_args(argv)
+
+    ret = 0
+    for filename in args.filenames:
+        ret |= fix_file(filename, args)
+    return ret
+
+
+if __name__ == '__main__':
+    exit(main())

requirements-dev.txt

+coverage
+flake8
+pre-commit
+pytest

setup.cfg

+[wheel]
+universal = True

setup.py

+from setuptools import setup
+
+setup(
+    name='add_trailing_comma',
+    description='Automatically add trailing commas to calls and literals',
+    url='https://github.com/asottile/add_trailing_comma',
+    version='0.0.0',
+    author='Anthony Sottile',
+    author_email='asottile@umich.edu',
+    classifiers=[
+        'License :: OSI Approved :: MIT License',
+        'Programming Language :: Python :: 2',
+        'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Programming Language :: Python :: Implementation :: PyPy',
+    ],
+    install_requires=['tokenize-rt'],
+    py_modules=['add_trailing_comma'],
+    entry_points={
+        'console_scripts': ['add-trailing-comma = add_trailing_comma:main'],
+    },
+)

tests/add_trailing_comma_test.py

+# -*- coding: utf-8 -*-
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+from add_trailing_comma import main
+
+
+def test_main_trivial():
+    assert main(()) == 0
+
+
+def test_main_noop(tmpdir):
+    f = tmpdir.join('f.py')
+    f.write('x = 5\n')
+    assert main((f.strpath,)) == 0
+    assert f.read() == 'x = 5\n'
+
+
+# def test_main_changes_a_file(tmpdir, capsys):
+#     f = tmpdir.join('f.py')
+#     f.write('x(\n    1\n)\n')
+#     assert main((f.strpath,)) == 1
+#     out, _ = capsys.readouterr()
+#     assert out == 'Rewriting {}\n'.format(f.strpath)
+#     assert f.read() == 'x(\n    1,\n)\n'
+
+
+def test_main_syntax_error(tmpdir):
+    f = tmpdir.join('f.py')
+    f.write('from __future__ import print_function\nprint 1\n')
+    assert main((f.strpath,)) == 0
+
+
+def test_main_non_utf8_bytes(tmpdir, capsys):
+    f = tmpdir.join('f.py')
+    f.write_binary('# -*- coding: cp1252 -*-\nx = €\n'.encode('cp1252'))
+    assert main((f.strpath,)) == 1
+    out, _ = capsys.readouterr()
+    assert out == '{} is non-utf-8 (not supported)\n'.format(f.strpath)
+
+
+# def test_py35_plus_argument_star_args(tmpdir):
+#     f = tmpdir.join('f.py')
+#     f.write('x(\n    *args\n)\n')
+#     assert main((f.strpath,)) == 0
+#     assert f.read() == 'x(\n    *args\n)\n')
+#     assert main((f.strpath, '--py35-plus')) == 1
+#     assert f.read() == 'x(\n    *args,\n)\n'

tox.ini

+[tox]
+project = add-trailing-comma
+# These should match the travis env list
+envlist = py27,py35,py36,pypy
+
+[testenv]
+deps = -rrequirements-dev.txt
+commands =
+    coverage erase
+    coverage run -m pytest {posargs:tests}
+    coverage report --show-missing --fail-under 100
+    pre-commit install -f --install-hooks
+    pre-commit run --all-files
+
+[testenv:venv]
+envdir = venv-{[tox]project}
+commands =
+
+[pep8]
+ignore = E265,E309,E501