Contributing

Contributing in the form of code, feedback, ideas or bug reports are welcome. Code contributions are expected to pass all tests and style checks. If there are any problems let us know.

Before doing any major changes we recommend creating an issue or chatting with us on gitter to discuss first. In this way you do not get started on the wrong track and wasting time.

Being a testing framework we value automated testing and all contributions in both the Python and VHDL/SystemVerilog domain are expected to add new tests along with the new functionality.

Copyright

Any contribution must give the copyright to Lars Asplund. This is necessary to manage the project freely. Copyright is given by adding the copyright notice to the beginning of each file.

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# You can obtain one at http://mozilla.org/MPL/2.0/.
#
# Copyright (c) 2014-2024, Lars Asplund lars.anders.asplund@gmail.com

Python related

Running the Python tests

The test suite is divided into three parts:

tests/unit/

Short and concise unit tests for internal modules and classes.

tests/acceptance/

End to end tests of public functionality. Depends on external tools such as simulators.

tests/lint/

Style checks such as pycodestyle and license header verification.

The test suites must pass with Python 3.x as well as with all supported simulators.

For running the tests locally we recommend using pytest. In fact, pytest is required for running the acceptance tests, because some specific features are used for allowing certain tests to fail. See How to use skip and xfail to deal with tests that cannot succeed.

Example of running all unit tests

pytest tests/unit/

Dependencies

Other than the dependencies required to use VUnit as a user the following are also required for developers to run the test suite manually:

pycodestyle

Coding style check.

pylint

Code analysis.

mypy

Optional static typing for Python.

Code coverage

Code coverage can be measured using the coverage tool. The following commands measure the code coverage while running the entire test suite:

vunit/ > coverage run --branch --source vunit/ -m unittest discover tests/
vunit/ > coverage html --directory=htmlcov
vunit/ > open htmlcov/index.html

Developers should ensure that new code is well covered. As of writing this paragraph the total coverage was 92%. Missing coverage can be analyzed by opening the generated htmlcov/index.html produced by the above commands.

VHDL related

Running the VHDL tests

Each part of the VUnit VHDL code base has tests with a corresponding run.py file. For example vunit/vhdl/verification_components/run.py.

VHDL example

Example of running all verification component tests

python vunit/vhdl/verification_components/run.py

Coding Style

Contributions of VHDL code should blend in with the VUnit code style.

• Use lower case and snake_case for all identifiers and keywords.

• Do not use prefixes or suffixes like _c or _g for constants.

• Use _t suffix for type like <typename>_t.

• Never use the fact that VHDL is case-insensitive; Do not use Foo and foo to refer to the same identifier.

• Name array types <base_type_name>_vec_t

• Name packages with suffix _pkg

• Name files the same as the package or entity they contain such as <entity_name>.vhd

• Never put more than one entity/package in the same file.

• Keep the architecture in the same file as the entity unless there are several architectures. When there are several architectures put them all in separate files named <entity_name>_<architecture_name>.vhd.

• Put comments documenting functions and procedures above the declaration in the package header rather than the definition in the package body.

Regarding formatting use look at other VHDL files and follow that style. For example examples/vhdl/uart/src/uart_tx.vhd

Continous Integration

VUnit runs all test and lint checks on both GNU/Linux and Windows with several versions of Python (typically, the oldest and newest supported by both VUnit and the CI environment). GHDL is used to run the VHDL tests of all our libraries and examples.

All tests will be automatically run on any pull request and they are expected to pass for us to approve the merge.

Any commit on master that has a successful CI run will automatically update the VUnit website

Testing with Tox

VUnit uses the Python tox tool in the CI flow. Typically developers do not need to run this on their local machine.

Tox makes it easier to automatically test VUnit in various configurations. Tox automates creation of virtual environments and installation of dependencies needed for testing. In fact, all of the tests can be run in a single command:

vunit/ > tox

If tox is not available in your Python environment, it can be installed from PyPI with pip:

vunit/ > pip install tox

For most developers, running the full testsuite will likely lead to failed test cases because not all Python interpreters or HDL simulators are installed in their environment. More focused testing is possible by specifying which tox “environments” should be tested. For example, assume a developer uses Python 3.8 and Modelsim and would like to test changes using tools available in his environment:

vunit/ > tox -e py38-unit,py38-acceptance-modelsim

A full list of test environments can be seen by issuing the following command:

vunit/ > tox -l

Making releases

Important

Reference Release Notes Instructions for creating relevant news fragments that will be added to the Release notes.

Releases are automatically made by GitHub Actions on any master commit which is tagged.

To create a new tagged release commit:

• Build the docs and review the content of docs/news.inc.

  • If necessary, create additional news files and build the docs again.

• Add the news summary as the release notes and remove news fragments:

  mv docs/news.inc docs/release_notes/X.Y.Z.rst
  git add docs/release_notes/X.Y.Z.rst
  git rm -f docs/news.d/*.rst
  

• Execute python tools/release.py create X.Y.Z.

  • Will make and tag a commit with the new about.py version, the release notes and removed news files.

  • Will make another commit setting about.py to the next development version.

• Push the tag to remote to trigger the release build.

  • git push origin vX.Y.Z

• If the release build is successful, you can push the two commits to master.

  • git push origin master

  • If, in the meantime, a new commit has come into origin/master the two commits have to be merged into origin/master.

The CI service makes a release by uploading a new package to PyPI when a tag named vX.Y.Z is found in Git. A new release will not be made if:

• The X.Y.Z release is already on PyPI.

• The repo tag does not exist.

Submodule related

As of VUnit v4.7.0, the version of the submodules is printed in the corresponding add_* methods of builtins.py. Therefore, when bumping the submodules, maintainers/contributors need to remember modifying the string to match the new version.

Furthermore, since OSVVM is tagged periodically, bumping from tag to tag is strongly suggested.

Release Notes Instructions

The release notes directory contains “newsfragments” which are short (reST formatted) files that contain information for users.

Make sure to use full sentences in the past or present tense and use punctuation.

Each file should be named like <issue #>.<type>.rst, where <issue #> is the GitHub issue or pull request number, and <type> is one of:

• breaking:may break existing functionality; such as feature removal or behavior change.

• bugfix: fixes a bug.

• doc: related to the documentation.

• deprecation: feature deprecation.

• feature: backwards compatible feature addition or improvement.

• misc: a ticket was closed, but it is not necessarily important for the user.

For example: 123.feature.rst, 456.bugfix.rst.

Hint

towncrier preserves multiple paragraphs and formatting (code blocks, lists, and so on), but for entries other than features, it is usually better to stick to a single paragraph to keep it concise.