Practical use cases

Workflow tests.yml from repo VUnit/tdd-intro showcases five procedures to setup continuous integration in GitHub Actions, using GHDL and VUnit as a regression framework. The entrypoint to all the jobs is the same pytest script (, thus, all jobs are equivalent solutions. Tests called through pytest can be defined in any language: VUnit scripts, bash/shell scripts, makefiles, etc.

It is suggested for new users to clone/fork this template repository, and then remove the jobs they don’t want to use. Since all are equivalent, using a single job is enough to have HDL designs tested. However, it might be useful to have designs tested on different platforms.


Uses Docker Action VUnit/vunit_action, based on image ghdl/vunit:llvm (see ghdl/docker: VUnit). It takes a single optional argument: the path to the See VUnit/vunit_action: for further info.

This is the most straightforward solution, and the one with fastest startup.


Docker based job, which can be used in any CI system. An (optional) Dockerfile is used to add some packages on top of image ghdl/vunit:llvm (see Customizing existing images). However, the same procedure can be used with any other image.

This is equivalent to lin-vunit, but it is slightly more verbose.


Uses JavaScript Action ghdl/setup-ghdl-ci to install GHDL on the Ubuntu host/VM. Then, additional system packages and Python packages are installed explicitly.

Compared to previous approaches, in this case runtime dependencies are not pre-installed. As a result, startup is slightly slower.


Uses Actions ghdl/setup-ghdl-ci and msys2/setup-msys2 to install latest nightly GHDL, other MSYS2 packages and Python packages in a clean MINGW64 environment.

This is the recommended approach to run tests on Windows. Action setup-msys2 caches installed packages/dependencies automatically.


The traditional procedure of downloading a tarball/zipfile from GHDL’s latest stable release. Additional Python packages are installed explicitly.

This is more verbose than the previous approach, but it’s currently the only solution to use latest stable GHDL without building it from sources.

Repositories using VUnit for CI

This is a non-exhaustive list of projects where VUnit is used for testing HDL designs: