.. _chapter-pw-presubmit:

.. default-domain:: cpp

.. highlight:: sh

------------
pw_presubmit
------------
The presubmit module provides Python tools for running presubmit checks and
checking and fixing code format. It also includes the presubmit check script for
the Pigweed repository, ``pigweed_presubmit.py``.

Compatibility
=============
Python 3

pw_presubmit Python package
===========================

Presubmit tools
---------------
A presubmit check is defined as a function or other callable. The function may
take either no arguments or a list of the paths on which to run. Presubmit
checks communicate failure by raising any exception.

For example, either of these functions may be used as presubmit checks:

.. code-block:: python

  @pw_presubmit.filter_paths(endswith='.py')
  def file_contains_ni(paths):
      for path in paths:
          with open(path) as file:
              contents = file.read()
              if 'ni' not in contents and 'nee' not in contents:
                  raise PresumitFailure('Files must say "ni"!', path=path)

  def run_the_build():
      subprocess.run(['make', 'release'], check=True)

Presubmit checks are provided to the ``parse_args_and_run_presubmit`` or
``run_presubmit`` function as a list. For example,

.. code-block:: python

  PRESUBMIT_CHECKS = [file_contains_ni, run_the_build]
  sys.exit(0 if parse_args_and_run_presubmit(PRESUBMIT_CHECKS) else 1)

Presubmit checks that accept a list of paths may use the ``filter_paths``
decorator to automatically filter the paths list for file types they care about.

Members
^^^^^^^
.. autofunction:: pw_presubmit.run_presubmit

.. autofunction:: pw_presubmit.parse_args_and_run_presubmit

.. autodecorator:: pw_presubmit.filter_paths

.. autofunction:: pw_presubmit.call

.. autoexception:: pw_presubmit.PresubmitFailure

Presubmit checks
----------------
The pw_presubmit package includes presubmit checks that can be used with any
project. These checks include:

* Check code format of several languages including C, C++, and Python
* Initialize a Python environment
* Run all Python tests
* Run pylint
* Ensure source files are included in the GN and Bazel builds
* Build and run all tests with GN
* Build and run all tests with Bazel
* Ensure all header files contain ``#pragma once``

pw_presubmit.format_code
------------------------
The ``format_code`` submodule formats supported source files using external code
format tools. The file ``format_code.py`` can be invoked directly from the
command line or from ``pw`` as ``pw format``.