Add dev dependencies and pre-commit configuration

Author: nicoddemus

.pre-commit-config.yaml

@@ -0,0 +1,26 @@
+repos:
+-   repo: https://github.com/ambv/black
+    rev: 18.6b4
+    hooks:
+    -   id: black
+        args: [--safe, --quiet]
+        language_version: python3.6
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v1.3.0
+    hooks:
+    -   id: trailing-whitespace
+    -   id: end-of-file-fixer
+    -   id: flake8
+-   repo: local
+    hooks:
+    -   id: rst
+        name: rst
+        entry: rst-lint --encoding utf-8
+        files: ^(CHANGELOG.rst|HOWTORELEASE.rst|README.rst|changelog/.*)$
+        language: python
+        additional_dependencies: [pygments, restructuredtext_lint]
+        python_version: python3.6
+-   repo: https://github.com/pre-commit/pygrep-hooks
+    rev: v1.0.0
+    hooks:
+    -   id: rst-backticks

docs/index.rst

@@ -846,6 +846,19 @@ projects rely on it. Our Github integrated CI process runs the full
 `tox test suite`_ on each commit so be sure your changes can run on
 all required `Python interpreters`_ and ``pytest`` versions.
 
+For development, we suggest to create a virtual environment and install ``pluggy`` in
+editable mode and ``dev`` dependencies::
+
+    $ python3 -m venv .env
+    $ source .env/bin/activate
+    $ pip install -e .[dev]
+
+To make sure you follow the code style used in the project, install ``pre-commit`` which
+will run style checks before each commit::
+
+    $ pre-commit install
+
+
 Release Policy
 **************
 Pluggy uses `Semantic Versioning`_. Breaking changes are only foreseen for

setup.py

@@ -37,6 +37,12 @@ def main():
         author_email='[email protected]',
         url='https://github.com/pytest-dev/pluggy',
         python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
+        extras_require={
+            "dev": [
+                "pre-commit",
+                "tox",
+            ]
+        },
         classifiers=classifiers,
         packages=['pluggy'],
     )