152 lines
5.2 KiB
ReStructuredText
152 lines
5.2 KiB
ReStructuredText
Introduction
|
|
============
|
|
|
|
hacking is a set of flake8 plugins that test and enforce the
|
|
`OpenStack StyleGuide <https://docs.openstack.org/hacking/latest/user/hacking.html#styleguide>`_
|
|
|
|
Hacking pins its dependencies, as a new release of some dependency can break
|
|
hacking based gating jobs. This is because new versions of dependencies can
|
|
introduce new rules, or make existing rules stricter.
|
|
|
|
Installation
|
|
============
|
|
|
|
hacking is available from pypi, so just run::
|
|
|
|
pip install hacking
|
|
|
|
This will install specific versions of ``flake8`` with the ``hacking``,
|
|
``pep8``, ``mccabe`` and ``pyflakes`` plugins.
|
|
|
|
Origin
|
|
======
|
|
|
|
Hacking started its life out as a text file in Nova's first commit. It was
|
|
initially based on the `Google Python Style Guide`_, and over time more
|
|
OpenStack specific rules were added. Hacking serves several purposes:
|
|
|
|
1. Agree on a common style guide so reviews don't get bogged down on style
|
|
nit picks. (example: docstring guidelines)
|
|
2. Make code written by many different authors easier to read by making the
|
|
style more uniform. (example: unix vs windows newlines)
|
|
3. Call out dangerous patterns and avoid them. (example: shadowing built-in
|
|
or reserved words)
|
|
|
|
Initially the hacking style guide was enforced manually by reviewers, but this
|
|
was a big waste of time so hacking, the tool, was born to automate
|
|
the process and remove the extra burden from human reviewers.
|
|
|
|
.. _`Google Python Style Guide`: https://google.github.io/styleguide/pyguide.html
|
|
|
|
Versioning
|
|
==========
|
|
|
|
hacking uses the ``major.minor.maintenance`` release notation, where maintenance
|
|
releases cannot contain new checks. This way projects can gate on hacking
|
|
by pinning on the ``major.minor`` number while accepting maintenance updates
|
|
without being concerned that a new version will break the gate with a new
|
|
check.
|
|
|
|
For example a project can depend on ``hacking>=0.10.0,<0.11.0``, and can know
|
|
that ``0.10.1`` will not fail in places where ``0.10.0`` passed.
|
|
|
|
|
|
Adding additional checks
|
|
========================
|
|
|
|
Each check is a pep8 plugin so read
|
|
|
|
- https://github.com/jcrocholl/pep8/blob/master/docs/developer.rst#contribute
|
|
|
|
The focus of new or changed rules should be to do one of the following
|
|
|
|
- Substantially increase the reviewability of the code (eg: H301, H303)
|
|
as they make it easy to understand where symbols come from)
|
|
- Catch a common programming error that may arise in the future (H201)
|
|
- Prevent a situation that would 100% of the time be -1ed by
|
|
developers (H903)
|
|
|
|
But, as always, remember that these are Guidelines. Treat them as
|
|
such. There are always times for exceptions. All new rules should
|
|
support noqa.
|
|
|
|
If a check needs to be staged in, or it does not apply to every project or its
|
|
branch, it can be added as off by default.
|
|
|
|
Requirements
|
|
------------
|
|
- The check must already have community support. We do not want to dictate
|
|
style, only enforce it.
|
|
- The canonical source of the OpenStack Style Guidelines is
|
|
`StyleGuide <https://docs.openstack.org/hacking/latest/user/hacking.html#styleguide>`_,
|
|
and hacking just enforces
|
|
them; so when adding a new check, it must be in ``HACKING.rst``
|
|
- False negatives are ok, but false positives are not
|
|
- Cannot be project specific, project specific checks should be `Local Checks`_
|
|
- Include extensive tests
|
|
- Registered as entry_points in ``setup.cfg``
|
|
- Error code must be in the relevant ``Hxxx`` group
|
|
- The check should not attempt to import modules from the code being checked.
|
|
Importing random modules, has caused all kinds of trouble for us in the past.
|
|
|
|
|
|
Enabling off-by-default checks
|
|
==============================
|
|
|
|
Some of the available checks are disabled by default. These checks are:
|
|
|
|
- [H106] Don't put vim configuration in source files.
|
|
- [H203] Use assertIs(Not)None to check for None.
|
|
- [H204] Use assert(Not)Equal to check for equality.
|
|
- [H205] Use assert(Greater|Less)(Equal) for comparison.
|
|
- [H210] Require 'autospec', 'spec', or 'spec_set' in
|
|
mock.patch/mock.patch.object calls
|
|
- [H904] Delay string interpolations at logging calls.
|
|
|
|
To enable these checks, edit the ``flake8`` section of the ``tox.ini`` file.
|
|
For example to enable H106 and H203:
|
|
|
|
.. code-block:: ini
|
|
|
|
[flake8]
|
|
enable-extensions = H106,H203
|
|
|
|
Local Checks
|
|
============
|
|
|
|
hacking supports having local changes in a source tree. They need to
|
|
be registered individually in tox.ini:
|
|
|
|
Add to tox.ini a new section `flake8:local-plugins` and list each plugin with
|
|
its entry-point. Additionally, you can add the path to the files
|
|
containing the plugins so that the repository does not need to be
|
|
installed with the `paths` directive.
|
|
|
|
.. code-block:: ini
|
|
|
|
[flake8:local-plugins]
|
|
extension =
|
|
N307 = checks:import_no_db_in_virt
|
|
N325 = checks:CheckForStrUnicodeExc
|
|
paths =
|
|
./nova/hacking
|
|
|
|
The plugins, in the example above they live in
|
|
`nova/hacking/checks.py`, need to annotate all functions with `@core.flake8ext`
|
|
|
|
.. code-block:: python
|
|
|
|
from hacking import core
|
|
...
|
|
@core.flake8ext
|
|
def import_no_db_in_virt(logical_line, filename):
|
|
...
|
|
|
|
class CheckForStrUnicodeExc(BaseASTChecker):
|
|
name = "check_for_str_unicode_exc"
|
|
version = "1.0"
|
|
...
|
|
|
|
Further details are part of the `flake8 documentation
|
|
<https://flake8.pycqa.org/en/latest/plugin-development/index.html>`_.
|