Require black and isort for contributions

.travis.yml

@@ -21,5 +21,11 @@ jobs:
     - name: "check file consistency"
       script: ./tests/check_consistent.py
     - name: "flake8"
-      install: pip install -r requirements-tests-py3.txt
+      install: pip install $(cat requirements-tests-py3.txt | grep flake8)
       script: flake8
+    - name: "black"
+      install: pip install $(cat requirements-tests-py3.txt | grep black)
+      script: black --check --diff stdlib third_party
+    - name: "isort"
+      install: pip install $(cat requirements-tests-py3.txt | grep isort)
+      script: isort --check-only --diff --recursive stdlib third_party

CONTRIBUTING.md

@@ -16,6 +16,7 @@ are important to the project's success.
     * IMPORTANT: For new libraries, [get permission from the library owner first](#adding-a-new-library).
     * Create your stubs [conforming to the coding style](#stub-file-coding-style).
     * Make sure your tests pass cleanly on `mypy`, `pytype`, and `flake8`.
+    * Reformat your stubs with black and isort.
 4. [Submit your changes](#submitting-changes):
     * Open a pull request
     * For new libraries, [include a reference to where you got permission](#adding-a-new-library)
@@ -238,8 +239,14 @@ rule is that they should be as concise as possible.  Specifically:
 * use variable annotations instead of type comments, even for stubs
   that target older versions of Python;
 * for arguments with a type and a default, use spaces around the `=`.
-The code formatter [black](https://github.com/psf/black) will format
-stubs according to this standard.
+
+Stubs should be reformatted with the formatters
+[black](https://github.com/psf/black) and
+[isort](https://github.com/timothycrosley/isort) before submission.
+These formatters are included in typeshed's `requirements-tests-py3.txt` file.
+A sample `pre-commit` file is included in the typeshed repository.  Copy it
+to `.git/hooks` and adjust the path to your virtual environment's `bin`
+directory to automatically reformat stubs before commit.
 
 Stub files should only contain information necessary for the type
 checker, and leave out unnecessary detail:

pre-commit

@@ -0,0 +1,16 @@
+#!/bin/sh
+#
+# An example hook script that will reformat stubs using black and isort
+# prior to committing. Adjust BIN_DIR to where your black and isort
+# scripts are located.
+#
+# To enable this hook, copy this file to ".git/hooks".
+
+BIN_DIR=./.venv/bin
+
+CHANGED_FILES=$(git diff --cached --name-only --diff-filter=AM | grep .pyi)
+
+if test -n "${BIN_DIR}"; then
+    ${BIN_DIR}/black ${CHANGED_FILES}
+    ${BIN_DIR}/isort -y ${CHANGED_FILES}
+fi

stdlib/3/encodings/__init__.pyi

@@ -1,3 +1,6 @@
+# This commit serves as a workaround for timothycrosley/isort#1027 and can
+# be removed when a release with a fix was released.
+
 import codecs
 
 def search_function(encoding: str) -> codecs.CodecInfo: ...

stdlib/3/io.pyi

@@ -1,11 +1,8 @@
-from typing import (
-    List, BinaryIO, TextIO, Iterator, Union, Optional, Callable, Tuple, Type, Any, IO, Iterable
-)
 import builtins
 import codecs
 from mmap import mmap
 from types import TracebackType
-from typing import TypeVar
+from typing import IO, Any, BinaryIO, Callable, Iterable, Iterator, List, Optional, TextIO, Tuple, Type, TypeVar, Union
 
 _bytearray_like = Union[bytearray, mmap]